Project Name
Document Name
Frequency Sensitive
Electric Vehicle and
Heat Pump Power
Consumption
Final report
for
National Grid
July 17th 2015
Element Energy Limited
Terrington House
13-15 Hills Road
Cambridge CB2 1NL
Tel: 01223 852499
Fax: 01223 353475
1
Frequency Sensitive EV and Heat Pump Power Consumption
Final Report
Contents
1
2
Executive Summary........................................................................................................ 1
1.1
Potential - Electric Vehicles ....................................................................................... 3
1.2
Potential - Heat Pumps ............................................................................................. 4
1.3
Development path ..................................................................................................... 5
Introduction ..................................................................................................................... 7
2.1
Background ............................................................................................................... 7
2.2
Report structure ......................................................................................................... 7
PART 1 - Method .................................................................................................................... 9
3
4
Description of archetypes ............................................................................................. 10
3.1
Electric Vehicles ...................................................................................................... 10
3.2
Heat Pumps ............................................................................................................. 16
National Grid Service Requirements ............................................................................ 23
4.1
Future frequency response requirements ............................................................... 24
4.2
Seasonal and diurnal variation in response requirement ........................................ 25
4.3
Modelling method .................................................................................................... 25
PART 2 - Results .................................................................................................................. 27
5
6
7
Potential Frequency Response Contribution over Time............................................... 28
5.1
Potential future response from EVs ........................................................................ 28
5.2
Potential future response from heat pumps ............................................................ 33
Commercial potential .................................................................................................... 37
6.1
Costs of frequency response provision ................................................................... 37
6.2
Revenues per archetype ......................................................................................... 40
6.3
Cost benefit analysis ............................................................................................... 41
6.4
CO2 emissions impact ............................................................................................. 42
6.5
Commercial models ................................................................................................. 43
Technical barriers and challenges ................................................................................ 51
7.1
Electric Vehicles ...................................................................................................... 52
7.2
Heat Pumps ............................................................................................................. 53
7.3
Verification and telemetry ........................................................................................ 54
7.4
Network impacts and system operation .................................................................. 55
Frequency Sensitive EV and Heat Pump Power Consumption
Final Report
8
Roll Out ......................................................................................................................... 56
8.1 Summary of key barriers for the development of EV and heat pump frequency
response ........................................................................................................................... 57
9
8.2
Comparison of commercial procurement and mandatory provision ........................ 59
8.3
Next steps for EV and heat pump frequency response roll out ............................... 62
Conclusion .................................................................................................................... 64
Acknowledgements .............................................................................................................. 65
Glossary ............................................................................................................................... 66
References ........................................................................................................................... 68
Authors
For comments or queries please contact:
joris.besseling@element-energy.co.uk
rebecca.feeney-barry@element-energy.co.uk
shane.slater@element-energy.co.uk
Transmission.ukfes@nationalgrid.com
Frequency Sensitive EV and Heat Pump Power Consumption
Final Report
1 Executive Summary
National Grid has a licence obligation to control electricity system frequency within
statutory limits around 50Hz. System frequency is determined and controlled by the real
time balance between system demand and total generation. Historically, flexible electricity
generation is used to provide frequency response.
The electricity industry and the System Operator face new challenges as Great Britain
decarbonises. National Grid analysis for the 2014 System Operability Framework (SOF)
showed increasing challenges to managing system frequency within statutory limits
beyond 2020/2025. This is driven by increasing levels of intermittent renewable generation
and a consequent reduction in synchronised conventional generation.
At the same time, the uptake of new technologies such as electric vehicles (EVs) and heat
pumps is expected to increase. The corresponding increase in electricity demand may
pose further challenges to balancing the electricity system.
One of the four options identified in the SOF to address this challenge is to provide
frequency response by demand side management; using a large number of small loads
that have the potential to provide in aggregate a similar response capacity to a few large
generation plants. Different small loads could provide frequency response, and loads with
inherent storage or inertia are particularly suited, for example EVs and heat pumps.
In response, National Grid commissioned Element Energy to carry out this Network
Innovation Allowance (NIA) project to assess the potential for EVs and heat pumps to
contribute to frequency response.
A model was developed to assess the technical potential of EVs and heat pumps to
contribute to frequency response. The model schedules EV charging and heat pump
consumption for different power consumption archetypes, using historic traces for
frequency response requirements. Charging and consumption scheduling is constrained to
guarantee there is no adverse impact on the quality of service delivered to the customer.
In this study EV charging flexibility is provided by interrupting charging or changing charge
rates, but EV supply of electricity back to the grid (vehicle to grid) is excluded. The
projection of frequency response potential over time is further informed by National Grid
and external scenarios for the uptake of EVs and heat pumps.
The study then determines potential costs to technically enable frequency response and
operate a frequency response business, summarises the key technical and operational
challenges, reviews the commercial models that could support deployment, and identifies
possible next steps for the roll out of EV and heat pump frequency response service. As
part of the study, interviews were carried out with 22 stakeholders, including EV and heat
pump manufacturers, EV charge point manufacturers and operators, EV fleet operators,
electricity suppliers, DNOs and demand side aggregators.
1
Frequency Sensitive EV and Heat Pump Power Consumption
Final Report
Key results for 2030: combined potential of EVs & heat pumps
 1200MW combined annual average low frequency response potential
 Corresponding to an average 82% of projected 2030 requirement
 Representing £100 million per year revenues based on current prices
The analysis shows there is a significant technical potential for both EVs and heat pumps
to contribute to frequency response by 2030. The combined annual average potential may
reach 1200MW by 2030 in the medium uptake scenario (excluding residential heat
pumps). This corresponds to an average 82% of National Grid’s projected frequency
response requirement in 2030. The overall demand side potential may be significantly
higher when other loads, for example other electric heating technologies like storage
heaters or white goods like fridges, are also taken into account.
There are no fundamental technical limitations that prevent the implementation of
frequency responsive electricity consumption for either EVs or heat pumps. However,
further technical development is required for both technologies to realise practical
frequency response capability. Most heat pumps require further design iterations to meet
dynamic frequency response requirements in a safe and reliable manner. Key
development is also required in the control and communication systems, both between
EVs and charge points and heat pumps and Energy Management Systems, as well as with
demand side response (DSR) management platforms.
The annual average potential of EVs and heat pumps in the 2030 medium scenario
corresponds to approximately £100 million in annual revenues, based on current tendered
prices. This value could potentially be higher if the higher effectiveness of fast responding
demand assets in restoring system frequency deviations is taken into account in pricing.
While the overall cost of providing frequency response may be very competitive compared
to conventional thermal plants, the potential net benefit per household may be relatively
limited. This may risk limiting the participation of EV and heat pump owners in frequency
response schemes. Therefore, deployment will need to be supported by very efficient
commercial models or mandated. Commercial models may support combining frequency
response with other DSR uses, increasing the value of customer propositions. Moreover
equitable remuneration could be provided for fast and accurate responding demand assets
which may provide more effective frequency response management. Alternatively
frequency response provision could be mandated. However, this could inhibit the
development of innovative commercial models, charging and consumption management
(e.g. bidirectional charging for EVs) and the effective combination of different DSM
services.
Based on the modelling and analysis conducted for this report, the key findings are
detailed below.
2
Frequency Sensitive EV and Heat Pump Power Consumption
Final Report
Key results: EVs
Key results: heat pumps
 754MW annual average low
frequency response potential
 Corresponding to 52% of
projected 2030 requirement
 Representing £66 million per
year based on current prices
 Able to provide firm response
availability over the night when
combined with controlled smart
charging
 No fundamental technical
limitations to develop frequency
responsive capability
 Potential revenues of £45/EV/year
corresponding to a net annual
benefit of £26/year for a home
charging EV and £35/year for a
fleet EV
 Potential to avoid around 1 tonne
CO2 per year per EV
 447MW annual average low
frequency response potential from
commercial and industrial heat
pumps
 Corresponding to 30% of
projected 2030 requirement
 Representing £39 million per
year based on current prices
 Strong diurnal profile with limited
response availability over the night
 No fundamental technical
limitations to develop frequency
responsive capability
 Potential revenues of £70/year for
a residential heat pump and
£23/kW/year for a commercial
heat pump, corresponding to net
annual benefits of £51/year and
£21/kW/year respectively
 Potential to avoid 0.6 tonnes CO2
per year per kW electric for a
commercial heat pump and 2
tonnes per year for a residential
heat pump
1.1 Potential - Electric Vehicles



There is significant potential to provide frequency response via interrupted
charging because electric vehicles are projected to typically be available for
charging for 8 hours per day, but only require charging for 3 hours (for the home
charging archetype in the analysis)
EV batteries and battery management systems are typically capable of meeting
frequency response service requirements, with very high response rates and
accuracy. This near instantaneous response capability represents a further
opportunity, potentially reducing the overall required volume of frequency
response. This also implies that the contribution of EVs may be higher than 52%
of the total frequency response requirement in the medium uptake scenario, if their
fast response capability is utilised in frequency response management.
Current charge points are however not typically designed with all of the required
control, instrumentation and communication capabilities for providing frequency
response. There are no technical barriers to adapt standard chargers (mode 3 and
4) in design iterations, and additional hardware costs that meet specifications
suited for frequency response are estimated to be around £10. The impact of
dynamic frequency response on charging management and e.g. safety measures
has also not yet been tested in the field.
3
Frequency Sensitive EV and Heat Pump Power Consumption
Final Report


Total annual costs for frequency provision by a home charging EV are estimated
to be £19, including hardware, operational and overhead business costs. The total
1
for a fleet EV is lower, at £10, because the overhead cost is spread over the fleet .
This gives a net annual benefit of £26 for a home charging EV and £35 for a fleet
EV. This also demonstrates that average EV frequency response costs may be
lower than opportunity costs of conventional FR providers.
Currently there is no standardised protocol for communication between charge
points and aggregator management systems that are interoperable and support
frequency response requirements
1.2 Potential - Heat Pumps







There is a significant potential to provide frequency response by interrupting
consumption of heat pumps that are installed with thermal storage (e.g. a hot
water tank). The storage enables maintaining temperatures within customer
2
settings. Alternative opportunities include hybrid heat pumps that can switch to
natural gas, or to use the thermal inertia in the dwelling fabric.
The potential additional contribution of residential heat pumps may be very high
(approximately 2GW in the medium scenario in 2030). However this is very
dependent on the uptake of heat pumps in the residential sector, especially of
retrofits with space heating hot water storage.
The analysis is very sensitive to the extent to which heat pumps are installed with
thermal storage to provide flexibility, or the thermal inertia of dwellings, which is
very dwelling specific.
There is significant seasonal variation in heat pump response, as the response
available in January is nearly five times the response available in July.
Not all current heat pumps are able to meet ramp up speed of response
requirements for frequency response, while ramp down rates may be limited for
control and safety reasons. These issues can be addressed in the periodic
redesign of heat pumps, but require a driver for manufacturers to do so.
Currently there is no standardised protocol for communication between heat
pumps and aggregator management systems that are interoperable and support
frequency response requirements
Additional costs to adapt controls and enable metering may be higher than for
EVs. Total annual costs for frequency provision by a residential heat pump are
estimated to be £20, including hardware, operational and overhead business
3
costs. The total for a 10kW commercial heat pump is £24 . This gives a net annual
benefit of £51 for a residential heat pump and £206 for a 10kW electric
commercial heat pump. This also demonstrates that average heat pump frequency
response costs may be lower than opportunity costs of conventional FR providers.
The residential heat pump archetype has higher energy consumption than the EV home
charging archetype, and slightly higher uptake numbers. Consequently the overall
frequency response potential, as well as individual asset revenues, is higher for the heat
pump archetype.
However EVs may be able to provide faster response, providing more effective
frequency management and require less technical development to enable frequency
1
Assumes a fleet of 10 EVs. Annual costs are calculated over 15 years.
2responsive consumption. EVs provide moreover more flexibility in charging than heat
Not modelled explicitly in this study
3pump consumption. This enables EVs, when frequency sensitive consumption is
Annual costs calculated over 15 years.
combined with controlled smart charging, to provide more firm response throughout the
night period when National Grid requirements are highest.
4
Frequency Sensitive EV and Heat Pump Power Consumption
Final Report
1.3 Development path
Large fleets of kW scale EVs and heat pumps have different characteristics and
capabilities compared to conventional synchronised generators. Distributed loads that are
able to respond faster and more accurate than conventional generators, may become
increasingly valuable in helping to manage system frequency. A review of contractual
terms and conditions may be required to utilise the potentially more effective system
frequency management capabilities, and accommodate e.g. specific reliability and
availability characteristics. Stakeholders interviewed in this study identified that they need
clear indication of National Grid future frequency response requirements and confidence in
long term market value.
For EVs a commercial procurement model appears to be the most appropriate model to
develop. The study shows clear drivers to actively support the development of these
opportunities in the near future. For heat pumps both mandating and commercial
procurement may be appropriate. In parallel to further technology development the impact
and benefits of both may be investigated in more detail.
The development of commercial models and technologies requires investments from
technology developers and third parties developing technologies and customer
propositions. These investments can be de-risked by a dual approach supporting
technology and market development. This may provide industry confidence on the long
term access, value and market size for these solutions.
1.3.1 Next steps for EV and heat pump frequency response roll out
Supporting market development should focus on providing confidence that there will be a
market in the long term that is accessible and amenable to frequency response from EVs
and heat pumps, and values providers based on their effective contribution to resolving
frequency management.
1. Near term – strategic agenda and business case


Early developments may be supported by clear statements showing that
Frequency Response from a large portfolio of low power (kW scale) assets is
being actively explored as part of strategic agendas for system management.
Technology developers and aggregators can be supported in overcoming
technical barriers and uncertainty around real life business models, by supporting
demonstrations that prove the technology and commercial structures, in which;


National Grid provides clarity on service requirements (response rates,
response lengths, reliability), technical requirements (power metering,
verification) and contractual terms.
National Grid defines baseline methodology used to identify an asset’s
contribution to frequency response
2. Medium term – enabling deployment
 Provide commercial opportunities for early adopters through commercial bilateral contracts with less stringent technical requirements or novel
commercial models.
5
Frequency Sensitive EV and Heat Pump Power Consumption
Final Report


Collaborate with DNOs to identify impact on diversity. Develop industry rules
and processes to create transparency between aggregators, National Grid,
DNOs and suppliers on location and utilisation of frequency responsive
demand. Develop processes to mitigate or limit adverse local network impacts
(thermal overload or voltage stability issues).
Collaborate with aggregators and suppliers to identify impact on settlement
(system balance) or supplier imbalance if it is not the response aggregator.
Depending on the implementation of half hourly settlement, new SSCs may
need to be developed for different types of response providers.
3. Long term – market access
 Develop services which remunerate higher responsiveness that some demand
side technologies may provide (fast response capability, accurate tracking of
frequency deviations), and take into account challenges and limitations of
demand side technologies (short lead times for capacity nomination, profiled
bids).
 Implement industry processes and rules providing transparency between
DNOs, TSO and aggregators on location and utilisation of frequency
response, and implement processes to mitigate adverse local network impacts
1.3.2 Technology development
For both electric vehicles and heat pumps there are no fundamental technical barriers to
providing frequency response services. However further technical development is required
for both, especially for heat pumps, to realise practical frequency response capability;


EV hardware is technically capable of providing frequency response. Next steps in
technology development may focus on trialling control, automation and telemetry
in real world conditions, prior to commercial deployment.
Heat pumps are less technically ready. Next steps in technology development may
focus on developing the hardware capability. This would help to guarantee reliable
and safe operation for frequency response. Technological developments could
then be followed by real world trials focusing on control, automation and telemetry
in real world conditions, prior to commercial deployment.
The analysis has shown that with increasing uptake of EVs and heat pumps these demand
side technologies may be able to contribute significantly towards National Grid’s future
frequency response needs, at a competitive cost compared to conventional solutions.
There are no fundamental technical limitations to implement frequency responsive
electricity consumption for these technologies. However further technology development is
required, especially on control and automation, and communication and telemetry. The
technical capabilities of these assets may enable more effective frequency management,
and reduce the overall need for frequency response. However the value at an individual
asset level is diluted, which may limit the development of these opportunities. The
development of commercial models and technologies requires investments from
technology developers and third parties developing technologies and customer
propositions. These investments can be de-risked by a dual approach supporting
technology development and supporting commercial markets by National Grid, providing
confidence on the long term access, equitable remuneration and realistic market size for
these solutions.
6
Frequency Sensitive EV and Heat Pump Power Consumption
Final Report
2 Introduction
2.1 Background
National Grid has a licence obligation to control system frequency within the limits
specified in the ‘Electricity Supply Regulations’; +/- 1% of the nominal frequency of
50.00Hz. System frequency is determined and controlled by the real time balance between
system demand and total generation.
UK electricity demands are met by a mixture of conventional synchronous generation,
which has high levels of mechanical inertia, and zero inertia non-synchronous renewable
generation. When there is an event that triggers a frequency deviation (for example, a
plant outage), the system inertia provided by conventional generation slows the rate of
change of frequency, thus helping ensure system stability. Frequency response providers
are then used to arrest the frequency drop and restore system frequency. Historically
flexible electricity generation is used to provide frequency response.
Over the coming decades, intermittent renewable generation will account for a greater
proportion of the UK’s electricity supply. This will reduce the amount of mechanical inertia
available in the system. Without mitigating actions, National Grid will require a larger
volume of frequency response, while intermittent renewable generation is less flexible and
is currently less able to provide frequency response services.
In addition, the uptake of low carbon demand technologies such as electric vehicles and
heat pumps are projected to increase. These loads have the potential to increase
electricity demand, change the demand profile, and, without appropriate measures, these
loads could be inflexible.
Therefore the way in which the electricity system is balanced will need to change in order
to remain economic, efficient and coordinated.
One of the options identified in National Grid’s System Operability Framework (SOF) to
address this challenge is to provide frequency response by demand side management.
This involves using a large number of small loads that have the potential to provide in
aggregate a similar response capacity to a few large generation plants. Different small
loads could provide frequency response, and loads with inherent storage or inertia are
particularly suited, for example electric vehicles and heat pumps.
In response, National Grid commissioned Element Energy to carry out this Network
Innovation Allowance (NIA) project to assess the potential for electric vehicles and heat
pumps to contribute to frequency response.
2.2 Report structure
Section 3 – defines the EV and heat pump archetypes used in the analysis
Section 4 – summarises National Grid service requirements and projections for future
needs
Section 5 – summarise the analysis of the potential contribution of EVs and heat pumps to
frequency response
7
Frequency Sensitive EV and Heat Pump Power Consumption
Final Report
Section 6 – outlines the key commercial models that may be used for EV and heat pump
frequency response
Section 7 – assess the key technical and operational barriers and challenges
Section 8 – reviews the next steps in the roll out of EV and heat pump frequency response
8
Frequency Sensitive EV and Heat Pump Power Consumption
Final Report
PART 1 - Method
9
Frequency Sensitive EV and Heat Pump Power Consumption
Final Report
3 Description of archetypes
3.1 Electric Vehicles
Sales of electric vehicles (EVs) are increasing and there is the potential for high uptake out
to 2030. An EV can be defined as a vehicle propelled (fully or in part) by an electric motor
using batteries that are charged by an external power source. This definition covers
Battery Electric Vehicles (BEVs), Plug-in Hybrid Electric Vehicles (PHEVs) and Range
Extended Electric Vehicles (REEVs) as these all charge their batteries from an external
power source. However, it does not cover Hybrid Electric Vehicles (HEVs) that have an
electric motor and battery, but do not use an external power source to charge the battery.
A BEV, also known as a Pure Electric Vehicle, has an electric motor that relies exclusively
on the power supplied by a battery. The battery is charged by plugging the vehicle in to an
external power source. A PHEV has both an electric motor and an internal combustion
engine, which are both used to provide propulsion. The configuration in which they are
used depends on the model of the car, but all can travel a number of miles in electric only
mode and have their battery charged by an external power source. Finally, a REEV has
an electric motor and an internal combustion engine but gains all of its motive force from
the electric motor. The internal combustion engine is used to generate electricity beyond
the range of the battery.
Of these types of EV, BEVs typically have the largest battery capacity, while PHEVs have
smaller capacities. Table 1 shows typical battery capacities for different types of EVs.
Table 1: Typical EV battery capacities
4
Battery capacity (kWh)
0-4

Small two wheel
4-8



PHEV
Large two wheel
Quadricycles
8-20




REEV
PHEV
High performance two wheel
Small BEVs
20-50


BEV- cars and small/medium vans
REEV
50-100


BEV- high performance cars
Larger vans, trucks and buses including BEV,
PHEV and REEV
100+

Specialist and very large vehicles
4
A Guide to Electric Vehicle Infrastructure, BEAMA
10
Frequency Sensitive EV and Heat Pump Power Consumption
Final Report
In this study, we examine the potential for EVs to provide frequency response. The
analysis considers both Battery Electric Vehicles (BEVs) and Plug in Hybrid Electric
Vehicles (PHEVs).
The analysis considers frequency response provision by turning on and off charging or by
varying charge power, but excludes Vehicle-to-Grid energy transfer (V2G). This is because
V2G presents operational issues that are considered significant by many EV
manufacturers. These include concerns on battery degradation (due to the increased
number of charging/discharging cycles), energy loss due to round trip efficiency and the
challenge in guaranteeing that the vehicle will be fully charged when the customer needs
it.
EV charging can be broadly divided into two types: AC and DC charging. It should be
noted that the EV battery is always charged by DC, and the power supply from the grid is
AC. A conversion from AC to DC therefore needs to take place. For an AC charge point,
the conversion from AC to DC takes place inside the car using on-board equipment. This
equipment is limited in size and weight, and therefore cannot deal with very high charge
powers. For a DC charge point, AC is converted to DC inside the charge point. Space and
weight considerations are therefore not as important, and higher charge powers can be
accommodated.
5
The primary international standard governing electric vehicle charging is IEC 62196 . It
defines four charging ‘modes’ as follows:




Mode 1. Connection of the EV to a standard AC mains socket outlet. This mode is
not recommended in the UK because RCD (residual-current device) protection,
which is necessary to ensure shock protection, is not guaranteed for all socket
outlets.
Mode 2. Connection of the EV to a standard AC mains socket outlet, but with a
control box to inform the EV of the charge power that can be drawn and to provide
RCD protection. The power is limited to 3kW for domestic socket-outlets and to
7.4kW for industrial socket-outlets.
Mode 3. Connection of the EV to a charge point or EVSE (Electric Vehicle Supply
Equipment) supplying AC power. The charge point is able to communicate with
the EV to inform it of the available power, and there is safety interlocking between
the EV and charge point. A single phase Mode 3 system usually operates at
3.7kW or 7.4kW, while a three phase system may operate at a higher rate
(typically 11, 22 or 43kW).
Mode 4. Connection of the EV to a charge point supplying DC power. There is
communication between the EV and charge point to establish safety and define
the appropriate charge current. These have a wide range of charging capabilities
up to over 100kW.
The charging modes relevant for this report are Mode 3 and Mode 4, as these allow smart
control of vehicle charging and variation of charge power.
Mode 3 charge points are commonly used for home, workplace and public charging. Home
charging typically uses charge powers up to 7.4kW as higher powers require a three
phase grid connection. Workplace and public charging use a wide range of charge powers,
5
http://www.iec.ch/
11
Frequency Sensitive EV and Heat Pump Power Consumption
Final Report
6
and new installations tend to be higher power. At time of writing, Zap Map , a UK public
charge point map, had recorded 2240 slow AC charge points of up to 3kW, 4940 fast AC
charge points of power ranging from 7kW to 22kW and 322 rapid AC charge points of
power up to 43kW.
Mode 3 charge points use a specific protocol for communication between the charge point
5
and the EV, which is compliant with the IEC 61851 standard . It is worth noting that the
charge power supplied to the vehicle is limited by either the charge point power, the power
capacity of the cable connecting the charge point to the vehicle or the power handling
capacity of the on-board charger in the vehicle, whichever is lowest.
Mode 4 charge points tend to be larger pieces of equipment than Mode 3 and can provide
very high charge powers. They are therefore more suited to public and
industrial/commercial applications where the time available for charging is limited.
Currently, the most common Mode 4 charge point power is in the 20-50kW range and
powers at the 100kW level may be available in the medium term. At the time of writing,
Zap Map counts 764 public DC charge points in the UK.
The UK government encourages the uptake of EVs and the installation of EV charging
infrastructure by offering a number of grants. Grants are available when purchasing a plugin car or van and cover 35% of the cost for a car (up to £5,000) or 20% of the cost for a
van (up to £8,000). EV owners can also receive up to 75% off the capital cost of a home
charge point and associated installation costs (capped at £700) via a scheme administered
by the Office for Low Emission Vehicles (OLEV). If an EV owner or prospective owner
does not have off-street parking, they can also request that their local authority install a
public charge point on their street. Funding from OLEV is available to local authorities for
this purpose.
As previously mentioned, dedicated EV charging infrastructure (Mode 3 or Mode 4 charge
points) is a pre-requisite for smart management of EV charging. Smart EV charging may
7
bring many benefits, including minimising the increase in peak demand caused by EVs ,
allowing fleet operators to charge many vehicles at one site without upgrading their grid
connection, allowing increased penetration of renewable generation, or, as is explored in
this study, providing frequency response services to National Grid.
3.1.1 EV uptake projections and archetypes
Three scenarios for the uptake of EVs are used in this study. BEV and PHEV uptake
numbers are included. The ‘Medium’ and ‘Low’ scenarios are based on National Grid’s
‘Gone Green’ and ‘Slow Progression’ Future Energy Scenarios (FES) 2015. A ‘High’
scenario was also included, which is based on the base case scenario in previous Element
8
Energy analysis for the Low Carbon Vehicle Partnership (LowCVP) . Figure 1 shows the
predicted uptake of EVs for these three scenarios. Figure 2 shows the corresponding
predictions for the annual electricity consumption by EVs. All three scenarios use the same
assumptions on annual electricity demand per EV, from the National Grid FES 2015.
6
https://www.zap-map.com/
Impact & opportunities for wide scale EV deployment, Low Carbon London Report B1
8
LowCVP, Options and recommendations to meet the RED transport target, Element
Energy, 2014
7
12
Frequency Sensitive EV and Heat Pump Power Consumption
Final Report
Projected number of EVs
6,000,000
Number of EVs
5,000,000
4,000,000
High uptake
3,000,000
Medium uptake
2,000,000
Low uptake
1,000,000
0
2015 2017 2019 2021 2023 2025 2027 2029
Figure 1: EV uptake projections, including BEVs and PHEVs
16,000
14,000
12,000
10,000
8,000
6,000
4,000
2,000
0
High uptake
Medium uptake
Low uptake
2015
2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026
2027
2028
2029
2030
GWh
Projected annual electricity demand of EVs
Figure 2: Projected annual EV electricity demand, including BEVs and PHEVs
The uptake of electric vehicles was divided into four distinct charging archetypes:


Private vehicles:
o Home charging
o Work charging
o Public charging
Fleet vehicles
The division of vehicles into private and fleet was based on the Department for Transport
9
(DfT) vehicle licensing statistics for 2014 . Private vehicle charging archetypes were then
identified using data from the Ultra Low Carbon Vehicle (ULCV) Demonstrator
10
Programme . The ‘home’, ‘work’ and ‘public’ charging locations are included while ‘other’
and ‘unknown’ charging locations are excluded.
The breakdown of EV charging into these four archetypes, shown in Figure 3, is assumed
to be constant into the future. For the purposes of modelling ease, it is also assumed that
each EV falls exclusively into one of these four archetypes over time (this assumption is
9
https://www.gov.uk/government/statistical-data-sets/veh02-licensed-cars
Assessing the viability of EVs in daily life, The Ultra Low Carbon Vehicle Demonstrator
Programme, 2013
10
13
Frequency Sensitive EV and Heat Pump Power Consumption
Final Report
well supported in the case of home charging as the ULCV trial found that drivers with
home charging infrastructure used it 97% of the time). The archetype breakdown can
therefore be directly applied to the EV projected uptake numbers.
Fleet
9%
Public
11%
Home
47%
Work
33%
Figure 3: Breakdown of EV uptake by archetype, based on DfT and UCLV data
In the analysis presented in this report, public charging is excluded for frequency response
provision. This assumption is based on interviews with industry stakeholders, who
indicated that most charging at public charge points is opportunity charging, where the
time required to charge up the battery is similar or longer than the time the user intends to
stay connected for. This means that increasing the charging time by interrupting charging
or reducing charge rates for frequency provision would not be acceptable to EV drivers.
In order to model the response available from EVs, diurnal charge profiles were obtained
for the home, work and fleet archetypes. These were assumed to be the same for PHEVs
as for BEVs. For home and work charging, these profiles were derived using charge start
11
time data from the ULCV and Customer-Led Network Revolution (CLNR) EV trials.
These profiles were scaled to match BEV and PHEV daily energy requirements from the
12
National Grid FES and assume a charge power of 3kW, typical for a slow charger. The
PHEV energy consumption is on average 16% lower than for BEVs, providing a similar,
but slightly lower, charging potential for frequency response. Figure 4 and Figure 5 show
the resulting diurnal profiles for home and work charging respectively (for March, in the
2030 Medium uptake scenario). For fleet vehicles, a simple profile was constructed based
on information from interviews with fleet operators. This charge profile assumed that fleet
EVs plugged in to charge between 20:00 and 01:00. The assumptions on daily energy use
and charge power were the same as for home and work charging. The resulting aggregate
charge profile for fleet vehicles (again for March in the 2030 Medium uptake scenario), is
shown in Figure 6.
11
http://www.networkrevolution.co.uk/
In the FES, PHEVs have a 16% lower daily energy requirement than BEVs. This is
applied in the analysis.
12
14
Frequency Sensitive EV and Heat Pump Power Consumption
Final Report
Home Infrastructure Diurnal Profile
1,400
1,200
MW
1,000
800
600
400
200
0
Figure 4: Home charging diurnal profile, March 2030 (medium uptake)
Work Infrastructure Diurnal Profile
MW
1,600
1,400
1,200
1,000
800
600
400
200
0
Figure 5: Work charging diurnal profile, March 2030 (medium uptake)
Fleet Diurnal Profile
600
500
MW
400
300
200
100
0
Figure 6: Fleet charging diurnal profile March 2030 (medium uptake)
The EV daily energy requirement varies over the year due to changing drive patterns and
the use of in-car heating. This seasonal variation is obtained from CLNR EV trial data and
is applied to the analysis of EV response potential. Figure 7 shows the monthly variation in
15
Frequency Sensitive EV and Heat Pump Power Consumption
Final Report
the daily energy requirement relative to the annual average. As can be seen in this graph,
in January, the daily EV energy requirement was 9.8kWh/EV, 35% more than the annual
average, while in July it was 6.1kWh/EV, 16% less than the annual average. This is
assumed to be the same for PHEVs as for BEVs.
Seasonal variation in EV daily energy demand
12
kWh/EV
10
8
6
4
2
0
Jan
Feb Mar Apr May Jun
Jul
Aug Sep Oct Nov Dec
Figure 7: Seasonal variation in daily energy demand for a single EV, 2030 medium
scenario
3.1.2 EV charging windows
The flexibility in EV charging, essential for EVs to provide frequency response, arises from
the fact that EVs can be plugged in for much longer than their required charge time. This
flexibility will vary depending on the archetype and on the individual requirements of an
EV. In the analysis, home charging EVs are projected to typically be available for charging
for 8 hours per day, but only require charging for 3 hours.
Private vehicles, charged at home or work, do not have fully predictable patterns, but can
offer flexibility as the daily energy requirement is typically quite low and they are parked for
a significant proportion of their lifetime. Fleet vehicles have very predictable use patterns
but are less flexible as they tend to have higher energy requirements and less time
available for charging.
For this analysis, the time available for EV charging and the daily energy requirement are
assumed to be constant across archetypes. The constraints on EV charging time assumed
in the model are as follows:



EVs plugged in between 17:00 and 21:00 must be charged by 05:00
EVs plugged in between 21:00 and 01:00 must be charged by 06:00
Otherwise, EVs have 8 hours available for charging.
3.2 Heat Pumps
Heat pumps transfer heat from a lower temperature heat source to a higher temperature
heat sink. For example, they transfer heat from the lower temperature outside air to the
higher temperature indoor air to provide space heating. The principle of operation of a heat
pump is shown in Figure 8. The liquid in the evaporator (3) evaporates, absorbing heat
from outside. The resulting gas is then passed through the compressor (4), which
increases the pressure and causes it to condense in the condenser (1), thus releasing its
heat. The compressor is driven by electricity. Heat pumps can provide several times the
energy as heat output as they consume in electricity, unlike resistive heaters in which
16
Frequency Sensitive EV and Heat Pump Power Consumption
Final Report
electricity is converted to heat in a 1:1 ratio, making heat pumps a very efficient form of
electric heating.
Figure 8: Heat pump principle of operation
The heat pump heat source is typically the outside air or ground. Heat pumps that use
these heat sources are termed Air Source Heat Pumps (ASHPs) and Ground Source Heat
Pumps (GSHPs) respectively. The heat pump efficiency is measured by the Coefficient of
Performance (COP), which is the ratio of heat energy delivered to electrical energy
consumed. ASHPs can have a COP of up to 4 in mild weather, though this decreases in
colder weather as the temperature difference between the inside and outside air
increases. Typically, the COP of ASHPs is in the 2-3 range. GSHPs are not susceptible
the same efficiency fluctuations as ASHPs but are more expensive to install and require a
13
suitable ground source .
The heat pump compressor can be fixed speed, which means that the heat pump can only
operate at 100% power, or variable speed, which means that the power to the compressor
can be modulated enabling it to speed up or slow down depending on the heating
requirements of the building. The use of a variable speed compressor means that frequent
on/off cycles can be avoided and the heat output can be more precisely matched to the
need. It also means that the heat pump can ramp up when turned on, avoiding high startup currents. For these reasons, variable speed heat pumps are more efficient. New
domestic heat pump installations in the UK are typically variable speed, though there are
14
still some fixed speed models on the market .
The UK government supports heat pump uptake via the Renewable Heat Incentive (RHI).
The RHI rewards the production of renewable heat in retrofit installations via tariffs for
each unit of heat produced.
Heat pumps can contribute to DSR because of the thermal storage that can be present in
the form of a dedicated thermal store for space heating or in the thermal inertia of the
building. This means that they can be temporarily switched off or have their power reduced
while still keeping the building temperature at comfortable levels. Manufacturers also offer
hybrid heat pumps, which can provide heat via a heat pump or via an alternative fuel
source (boiler). These also offer possibilities for DSR as the hybrid heat pump can turn off
the heat pump and switch to its alternative fuel source when required, while still
13
The Energy Saving Trust, Getting warmer: a field trial of heat pumps, and the Energy
Saving Trust website (http://www.energysavingtrust.org.uk/domestic/renewable-heat).
14
Based on interviews with heat pump manufacturers.
17
Frequency Sensitive EV and Heat Pump Power Consumption
Final Report
maintaining the building temperature at the appropriate level. Hybrid heat pumps are not
explicitly looked at in the analysis presented in this report.
3.2.1 Heat pump uptake projections and archetypes
Three heat pump uptake scenarios are used in this study. The ‘High’ and ‘Low’ uptake
scenarios are from National Grid’s Gone Green and Slow Progression Future Energy
Scenarios (FES) 2015. A ‘Medium’ scenario is also included, based on previous Element
15
Energy work for the Committee on Climate Change (CCC) . Two heat pump archetypes,
defined in these uptake scenarios, are used in the analysis. These are residential and
commercial/industrial. In the low uptake scenario (Slow Progression FES 2015),
industrial/commercial heat pumps do not appear, so only residential heat pumps were
included in this scenario. Figure 9 shows the projected numbers for residential heat pumps
in all three scenarios, while Figure 10 shows the corresponding annual electricity
consumption by residential heat pumps. Figure 11 shows the projected electricity
consumption by industrial/commercial heat pumps.
15
P1: RHI driven uptake, CCC, Pathways to high penetration of heat pumps, Frontier
Economics and Element Energy, 2013
18
Frequency Sensitive EV and Heat Pump Power Consumption
Final Report
Projected number of residential heat pumps
Numver of heat pumps
6,000,000
5,000,000
4,000,000
High uptake
3,000,000
Medium uptake
2,000,000
Low uptake
1,000,000
2015
2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026
2027
2028
2029
2030
0
Figure 9: Residential heat pump uptake projections
16
Projected annual residential heat pump electricity demand
30,000
25,000
GWh
20,000
High uptake
15,000
Medium uptake
10,000
Low uptake
5,000
2015
2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026
2027
2028
2029
2030
0
Figure 10: Projected annual residential heat pump electricity demand
8,000
7,000
6,000
5,000
4,000
3,000
2,000
1,000
0
High uptake
Medium uptake
2015
2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026
2027
2028
2029
2030
GWh
Projected annual commercial/industrial heat pump
electricity demand
Figure 11: Projected annual commercial/industrial heat pump electricity demand
16
The shape of the medium uptake scenario, and the low and high uptake scenario are
different, as the medium scenario is the CCC scenario and low and high the National Grid
FES.
19
Frequency Sensitive EV and Heat Pump Power Consumption
Final Report
In order to model the response available from heat pumps, diurnal energy use profiles
were obtained for each archetype. The aggregate residential heat pump profile was
obtained from CLNR heat pump trial data. This profile was scaled by the residential heat
pump daily energy use. The annual average of the residential daily energy use was taken
from National Grid’s FES 2015, while the monthly variation in this energy use, shown in
17
Figure 13, was obtained from CLNR data . Figure 12 shows the resulting aggregate
residential heat pump profile for March in the 2030 medium uptake scenario. It is assumed
in the modelling that each residential heat pump has an electric power demand of 3kW.
This tends towards the lower end of the typical range for residential heat pump
installations, and is chosen because future heat pump installations are expected to be in
well-insulated homes with lower heating energy demands.
Heat Pump Residential Diurnal Profile
5,000
MW
4,000
3,000
2,000
1,000
0
Figure 12: Residential heat pump diurnal profile, March 2030 (medium uptake)
18
kWh/heat pump
Seasonal variation in residential heat pump daily
demand
30
20
10
0
Jan Feb Mar Apr May Jun
Jul
Aug Sep Oct Nov Dec
Figure 13: Seasonal variation in daily energy use for a single residential heat pump, 2030
medium scenario
The aggregate industrial/commercial profile was obtained in a similar way, though in this
case no trial data was available. A constructed profile, used in load modelling work for UK
19
Power Networks (UKPN) , which assumes near constant operation during the day and no
heat pump use at night, was therefore used. This was then scaled by the daily energy use.
17
http://www.networkrevolution.co.uk/
In summer, heating is mainly used for hot water provision and not for space heating,
which may change the summer diurnal profile. This effect is not taken into account here,
as the same profile shape from CLNR trial data is used throughout the year.
19
This load modelling work is described in Low Carbon London Report C3, Network
impacts of energy efficiency at scale
18
20
Frequency Sensitive EV and Heat Pump Power Consumption
Final Report
The annual average for the daily energy use was taken from National Grid’s FES 2015,
while the monthly variation, shown in Figure 15, was taken from UKPN’s network load
19
modelling work . Figure 14 shows the resulting aggregate industrial/commercial profile for
March in the 2030 medium uptake scenario.
MW
HP Commercial/Industrial Diurnal Profile
1,600
1,400
1,200
1,000
800
600
400
200
0
Figure 14: Commercial/industrial heat pump diurnal profile, March 2030 (medium uptake)
Seasonal variation in commercial/industrial heat pump
daily demand
GWh/day
30
20
10
0
Jan
Feb Mar Apr May Jun
Jul
Aug Sep Oct Nov Dec
Figure 15: Seasonal variation in daily energy use by all commercial/industrial heat pumps,
2030 medium scenario
3.2.2 Potential flexibility of heat pumps
In order to provide frequency response heat pumps are required to operate flexibly,
interrupting or changing electricity consumption in response to the system frequency, while
house temperature levels are maintained within comfort levels. This can be achieved
through thermal storage (e.g. hot water tank) for space heating, which is discharged when
the heat pumps is interrupted. Alternatively it can be provided by the heat stored in the
building’s fabric (thermal inertia). Another option is the use of hybrid heat pumps, which
can switch to gas-fired heating to provide flexibility in electricity consumption. Heat pumps
20
are typically, but not always, installed with a thermal storage . For retrofitted heat pumps
in existing homes there is not always sufficient space to install a thermal storage tank.
In the analysis presented in this report, it is assumed that residential heat pumps are
installed with thermal storage in the form of a 180L hot water tank. With the hot water
stored at 50ºC, and an indoor temperature of 20ºC, this represents approximately 6.5kWh
of thermal storage. Assuming a COP of 3, a heat pump with an electric power of 3kW
20
Based on interviews with heat pump manufacturers.
21
Frequency Sensitive EV and Heat Pump Power Consumption
Final Report
(typical of a domestic heat pump) would take around 45 minutes to deliver this energy.
Further assuming that the thermal storage inherent in the fabric of the building provides
another 15 minutes of flexibility, this gives a total thermal storage equivalent to 1 hour of
heat pump use, indicating that heat pump use can be shifted by 1 hour without impacting
comfort levels.
These heat pump flexibility assumptions are also supported by a modelling study by
21
Loughborough University , which found that for a house with high levels of insulation, the
time of operation of the heat pump in the property could be shifted by 1-2 hours without the
indoor temperature falling below 20ºC. This can be increased to 2-6 hours with the
inclusion of a 300L-500L buffer tank for thermal storage. Thus even without thermal
storage, the assumption that heat pump use can be shifted by an hour may still hold.
Most future heat pump installations are expected to be in insulated homes, but it is
uncertain whether significant thermal storage will be installed. The above assumptions on
heat pump flexibility are therefore subject to a large degree of uncertainty. This issue was
also raised by heat pump manufacturers and other stakeholders in interviews. Due to this
uncertainty, the sensitivity of the results to the heat pump shifting ability is examined in the
analysis. For transparency, and due to lack of available data, heat pump flexibility is
assumed to be constant across archetypes.
21
Assessing Heat Pumps as Flexible Load, Hong et al., Loughborough University, 2013
22
Frequency Sensitive EV and Heat Pump Power Consumption
Final Report
4 National Grid Service Requirements
National Grid has a license obligation to control the system frequency so that it remains
within ±1% of the nominal value of 50Hz, except in abnormal or exceptional
circumstances. While this is the statutory limit for deviations, the operational limit that
National Grid applies aims to keep the system frequency between 49.8Hz and 50.2Hz.
National Grid therefore holds a certain amount of generation and/or demand ready to
automatically respond to frequency deviations.
The frequency of the electricity system will deviate from the nominal value when there is a
mismatch in electricity supply and demand. When supply is greater than demand, the
frequency rises, and generation must be turned down or demand increased in response.
When supply is less than the demand, the system frequency falls and generation must be
ramped up or demand reduced in response.
National Grid procures frequency response services from a number of sources. All
generators covered by the Grid Code are required to have the capability to provide
Mandatory Frequency Response, by automatically changing their active power in response
to a frequency change. They can provide three different response services:



Primary response: full delivery of response (increase in generation or reduction in
demand) within 10 seconds of a frequency event, sustained for a further 20
seconds.
Secondary response: full delivery of response (increase in generation or reduction
in demand) within 30 seconds of a frequency event, sustained for a further 30
minutes.
High frequency response: full delivery of response (decrease in generation or
increase in demand) within 10 seconds of a frequency event, sustained
indefinitely.
National Grid also procures these frequency response services commercially through Firm
Frequency Response (FFR), which is open to a wide range of providers, including
providers of Mandatory Frequency Response. This creates a route to market for providers
whose services may otherwise be inaccessible.
Frequency response can be dynamic or non-dynamic (also called static). For dynamic
response, the generator or load responds constantly, in proportion to the frequency
deviation. For non-dynamic response, the response is provided in full when the frequency
deviation exceeds a set point. Dynamic response requires providers to provide a near
continuous output modulation, while static response is triggered only infrequently, in the
order of 30 events a year. Dynamic response places higher technical requirements on
providers and is typically valued higher than static response.
To participate in FFR, providers must be able to deliver a minimum 10MW response,
though this can be aggregated from multiple sites. National Grid also procures FFR
through FFR Bridging and bilateral contracts, which are for providers that do not yet meet
the 10MW minimum threshold for FFR or for those who can provide unique frequency
response services to National Grid.
Dynamic response is typically provided with a dead band of +/-0.015Hz. Technical
requirements for FFR providers furthermore include a relay sensitivity tolerance of 0.01Hz.
23
Frequency Sensitive EV and Heat Pump Power Consumption
Final Report
Providers are also required to communicate response data in real time second by second
or minute-by-minute (in which case post event second-by-second data needs to be sent
for verification). FFR can be bid for in any time period windows.
National Grid also procures frequency response through Frequency Control by Demand
Management (FCDM), where providers are prepared to interrupt their demand for 30
minutes 10-30 times a year.
4.1 Future frequency response requirements
UK electricity demands are met by a mixture of conventional synchronous generation,
which has high levels of mechanical inertia, and zero inertia non-synchronous renewable
generation. When there is an event that triggers a frequency deviation (for example, a
plant outage), the system inertia provided by conventional generation slows the rate of
change of frequency, thus helping ensure system stability, after which frequency response
providers are used to arrest the frequency drop and restore system frequency. With higher
renewable penetration, the system inertia will decrease. This means that a plant outage
will result in a faster frequency deviation. To counteract this, and to keep the grid
frequency within operational limits, National Grid will require a larger volume of frequency
response, or will need to acquire faster frequency response services. New wind turbine
controls are being developed that can provide synthetic inertia. This is another option that
may mitigate the loss of inertia from conventional generators and limits the amount of
additional frequency response that will be required.
Figure 16 shows the projected increase in National Grid’s mean primary frequency
response holding requirement to 2030 in both the Gone Green and Slow Progression
National Grid FES 2014 (for current service characteristics). The requirement in Gone
Green is higher than that in Slow Progression due to the higher proportion of zero-inertia
renewable generation in that scenario. In the Gone Green scenario, the 2030 mean
requirement is 1464MW while the maximum projected requirement for that year is
2738MW.
Mean primary frequency response requirement
1500
MW
1400
1300
Gone Green
1200
Slow progression
1100
1000
2015
2020
2025
2030
Figure 16: Future National Grid primary frequency response holding requirements
These projected holding requirements are obtained from illustrative National Grid
modelling which, given the mix and volume of electricity generation, outputs the amount of
22
low frequency response needed in case of a major 1800MW plant outage . The
22
It is assumed in the modelling that the minimum level this loss can be reduced to is
600MW in 2015 and 1800MW from 2020 onwards.
24
Frequency Sensitive EV and Heat Pump Power Consumption
Final Report
projections for the future mix and volume of electricity generation are obtained from
National Grid’s Gone Green and Slow Progression Future Energy Scenarios.
National Grid is also exploring the provision of faster frequency response services, for
example, through a rapid frequency response service. Rapid frequency response (low or
high) requires full delivery of response within 5 seconds and can be bid for in current FFR
tenders. National Grid is also investigating even faster response and synthetic inertia
services in the Enhance Frequency Control Capability Network Innovation Competition
project. The predictions of primary response requirement presented above are highly
dependent on whether such services, or other novel frequency response services, are
developed.
4.2 Seasonal and diurnal variation in response requirement
The projected primary response requirements presented above are annual averages.
However, the primary response requirement is modelled for each hour in a given year,
allowing the diurnal variation in requirement to be obtained. This is presented for the 2030
Gone Green scenario in Figure 17. The diurnal variation shown is the average over the
entire year.
Diurnal variation in 2030 primary frequency
response requirement
2500
MW
2000
1500
1000
500
0
Figure 17: Diurnal variation in average primary frequency response requirement, averaged
over the year, 2030 Gone Green scenario
The diurnal variation in average primary response requirement is shown in Figure 17. As
can be seen, the response requirement is highest overnight, between midnight and 06:00,
and is relatively constant through the day. This is due to the fact that the lower levels of
demand overnight mean that a single plant outage would have a much larger effect on
frequency.
4.3 Modelling method
4.3.1 Modelling method for EVs
To find how much response EVs could potentially provide, their charge profiles were
adjusted in response to system frequency deviation, based on 2014 half hourly frequency
response utilisation. A frequency responsive profile for each day in a given year could thus
be obtained, which allowed the calculation of the volume of low or high frequency
response provided when there was a signal. It was ensured throughout that vehicles were
fully charged by the end of their available charge period. This methodology is
demonstrated in an example cartoon profile for a single EV, shown in Figure 18. The EV is
25
Frequency Sensitive EV and Heat Pump Power Consumption
Final Report
plugged in to charge at 19:00, and must be charged by 06:00, but its charging is
interrupted due to low frequency signals.
Cartoon charging profile for a single EV
4
Normal charging profile
kW
3
Frequency responsive
profile
2
Low frequency signal
1
High frequency signal
06:00
05:00
04:00
03:00
02:00
01:00
00:00
23:00
22:00
21:00
20:00
19:00
18:00
0
Figure 18: Cartoon profile for a single EV responding to half hourly frequency signals to
demonstrate the modelling methodology
The aggregate normal diurnal and frequency responsive profiles for all EVs were
calculated for each day in the year for each scenario (each time using the 2014 half hourly
frequency signals). This allowed the calculation of the average low frequency and high
frequency response for each year and scenario as well as the seasonal and diurnal
variation in that average.
4.3.2 Modelling method for heat pumps
The method used for calculating heat pump frequency response is the same as for EVs,
but the constraints on when a heat pump can respond are different.
Similarly to the approach for EVs, the aggregate heat pump energy use profile was
adjusted in response to system frequency deviation, based on 2014 half hourly frequency
response utilisation. This gave a frequency responsive profile that allowed calculation of
the low frequency response and high frequency response provided by heat pumps. The
flexibility allowed in the energy use profile was defined by the amount of thermal storage
available (as described in Section 3.2.2, it was assumed that the volume of energy storage
available was equal to the energy delivered by the heat pump in one hour).
26
Frequency Sensitive EV and Heat Pump Power Consumption
Final Report
PART 2 - Results
27
Frequency Sensitive EV and Heat Pump Power Consumption
Final Report
5 Potential Frequency Response Contribution over Time
5.1 Potential future response from EVs
The analysis finds that the potential for frequency response from EVs increases strongly
after 2020. By 2030, EVs could contribute an average low frequency response of 754MW
in the medium uptake scenario, 52% of the projected average 2030 requirement. This
could rise to 1210MW, 83% of the projected requirement, in case of high EV uptake, and
could reduce to 377MW, 26% of the projected requirement, if EV uptake is low.
The annual average for low and high frequency response was calculated out to 2030 for all
EV uptake scenarios. As shown in Figure 19 and Figure 20, the response potential of EVs
increases with increased EV uptake, and becomes significant after 2020. Figure 19 shows
the potential for low frequency response, which would be achieved by switching off
charging or reducing the charge power.
Average low frequency response from EVs
1400
1200
MW
1000
800
High uptake
600
Medium uptake
400
Low uptake
200
0
2015
2020
2025
2030
Figure 19: Average low frequency response from EVs to 2030
The modelled potential for high frequency response is slightly lower than that for low
frequency response, as can be seen in Figure 20. High frequency response in the context
of EVs would be achieved by switching on charging or by increasing charge power. By
2030, this could contribute 577MW in the medium uptake scenario, rising to 926MW in the
high uptake scenario, and reducing to 289MW in the low uptake scenario.
28
Frequency Sensitive EV and Heat Pump Power Consumption
Final Report
Average high frequency response from EVs
1000
MW
800
600
High uptake
Medium uptake
400
Low uptake
200
0
2015
2020
2025
2030
Figure 20: Average high frequency response from EVs to 2030
5.1.1 Seasonal variation in response
The response from EVs varies over the course of the year as charge patterns and EV daily
energy use changes (see section 3.1.1). Figure 21 shows the monthly variation in average
low frequency response in 2030 for medium EV uptake. This shows that the seasonal
variation in response is small, with variations of approximately ±15% about the annual
average. The lowest response availability is in April, with 668MW of low frequency
response available in the 2030 medium scenario, while the highest is in January, with
891MW available in this same scenario. Thus, in January, EVs could provide 61% of low
frequency response requirements while in April they could provide 46%.
Seasonal variation in average low frequency response from
EVs, 2030 medium scenario
1,000
600
December
November
October
September
August
July
Home infrastructure
June
0
May
Work infrastructure
April
200
March
Fleet vehicles
February
400
January
MW
800
Figure 21: Monthly variation in average low frequency response from EVs, 2030 medium
scenario
Figure 21 also shows the breakdown of the available low frequency response by
archetype. The bulk of the response is provided by home and work charging with, on
average over the year, 53% of the response coming from home charging, 37% from work
charging and 10% from fleet vehicles.
29
Frequency Sensitive EV and Heat Pump Power Consumption
Final Report
5.1.2 Diurnal variation in response
In the charging strategy where EVs start charging when they are plugged in and respond
to deviations in system frequency, the response available from EVs varies significantly
within a given day. On average, with this charging strategy, EVs can offer very limited
frequency response in the early hours of the morning (03:00-04:00), while at the morning
and evening peak they could offer around 1500MW of low frequency response in the 2030
medium scenario. This corresponds to twice the average response, and, for the morning
peak, could provide over 120% of the projected low frequency response requirement (for
2030 under the Gone Green 2014 scenario).
A charging strategy where frequency sensitive consumption is combined with a controlled
smart charging strategy, in which the early evening charging peak is spread over the night
time, is also examined. Here the response available from home and work charging, which
usually peaks soon after they are plugged in to charge, is spread over the entire available
charging period, to 06:00. This gives a near constant response availability during the night
of around 830MW, approximately 40% of the average night time primary response
requirement (for 2030 under the Gone Green 2014 scenario).
To demonstrate the diurnal variation in EV response, the 2030 Medium scenario is once
again taken as an example. Figure 22 shows the diurnal variation in average low
23
frequency response from EVs, with current charging patterns , while Figure 23 shows the
diurnal variation with active charging management to spread home charging and fleet
vehicle response over the night. This average is calculated for each half hour over the
whole year, and is broken down into response from home, work and fleet archetypes.
This shows that with current charge patterns, the response is highest at 09:30 and at
22:30 and lowest at 03:00-04:00. The 09:30 peak mainly arises from cars plugging in to
charge after arrival at work while the 22:30 peak is mainly due to home charging. The lack
of available response in the early hours of the morning arises because cars are generally
either fully charged or obligated to charge without interruption (to ensure that they are fully
charged by morning).
This dip in response availability at 03:00-04:00 can be prevented through controlled smart
charging management, as shown in Figure 23. In this case, the charge start time of some
vehicles is delayed so as charging is more spread through the night. Assuming the
response provided by home charging and fleet EVs is evenly spread over the entire
available charge period results in a near constant response availability of approximately
830MW throughout the night.
23
Current charging patterns: EVs start charging on full power as soon as they are plugged
in
30
Frequency Sensitive EV and Heat Pump Power Consumption
Final Report
Diurnal variation in average low frequency response from EVs, 2030
medium scenario
2000
MW
1500
Fleet vehicles
1000
Work infrastructure
500
Home infrastructure
00:00
01:30
03:00
04:30
06:00
07:30
09:00
10:30
12:00
13:30
15:00
16:30
18:00
19:30
21:00
22:30
0
Figure 22: Diurnal variation in average low frequency response from EVs with current
charging patterns, 2030 medium scenario. Error bars show the standard deviation of the
total response.
1800
1600
1400
1200
1000
800
600
400
200
0
Fleet vehicles
Work infrastructure
Home infrastructure
00:00
01:30
03:00
04:30
06:00
07:30
09:00
10:30
12:00
13:30
15:00
16:30
18:00
19:30
21:00
22:30
MW
Diurnal variation inaverage low frequency response from EVs with
smart charging, 2030 medium scenario
Figure 23: Diurnal variation in average low frequency response from EVs with active
charging management, 2030 medium scenario. Error bars show the standard deviation of
the total response.
Figure 17 shows that the diurnal National Grid low frequency response requirement (for
2030 under the Gone Green 2014 scenario), averaged over the year, varies between
approximately 1200MW and 2000MW. The requirement is highest during the night, when
demand, and consequently the volume of synchronised generation, is lowest.
With baseline charge patterns, the available response from EVs is lowest in the early
hours of the morning, when the National Grid requirement is high. However, with controlled
smart charging management, the response from home charging and fleet EVs may be
spread throughout the night, and can provide approximately 40% of the night time 2030
primary response requirement (for 2030 under the Gone Green 2014 scenario). This is
shown in Figure 24 and Figure 25.
31
Frequency Sensitive EV and Heat Pump Power Consumption
Final Report
With large scale uptake of frequency sensitive EV consumption, the diurnal variation in
response availability may impact other providers of frequency response. Conventional
providers may be required to provide frequency response for shorter more specific
windows then they do at the moment. Alternatively, demand side assets with different
availability profiles may be aggregated to provide a more constant aggregated availability
profile. The other option is to only use the constant baseline EV response capability, and
to discard peak availability, so as to obtain a constant level of response.
Percentage of requirements satisfied by
EVs
Diurnal variation in proportion of National Grid requirements
satisfied by EVs
140%
120%
100%
80%
60%
40%
20%
0%
Figure 24: Diurnal variation in ability of EV response to meet the National Grid requirement
(Gone Green scenario) for current charging patterns, 2030 medium scenario
Percentage of requirements satisfied by
EVs
Diurnal variation in proportion of National Grid requirements
satisfied by EVs with smart charging
140%
120%
100%
80%
60%
40%
20%
0%
Figure 25: Diurnal variation in ability of EV response to meet the National Grid requirement
(Gone Green scenario) with smart charging management, 2030 medium scenario
32
Frequency Sensitive EV and Heat Pump Power Consumption
Final Report
5.2 Potential future response from heat pumps
The potential for frequency response from heat pumps increases steadily from 2015 with
increased heat pump uptake. By 2030, commercial and industrial heat pumps could
contribute an annual average low frequency response between 447MW and 585MW,
based on medium and high heat pump uptake scenarios. These figures respectively
correspond to 30% and 40% of the projected average low frequency response requirement
for 2030 under the Gone Green 2014 scenario. Including the response potential from
residential heat pumps, in the 2030 medium scenario heat pumps could provide 2.5GW of
low frequency response. This equates to 170% of the projected response requirement for
that year.
The annual average for low and high frequency response from heat pumps was
calculated out to 2030. Figure 26 and Figure 27 show the response potential increases
with heat pump uptake and could become significant before 2020 in both the medium and
high uptake scenarios, when residential installations are included.
Figure 26 shows the potential for low frequency response from heat pumps in future years,
including residential response. In 2030, heat pumps could provide an average low
frequency response of 2.5GW in the medium uptake scenario, 170% of the projected
primary response requirement (for 2030 under the Gone Green Scenario). This would
increase to 3.3GW, 227% of the response requirement, in the high scenario, and decrease
to 375MW, 27% of the response requirement if heat pump uptake is low.
Average low frequency response from HPs
3500
High uptake (I&C)
3000
Medium uptake (I&C)
MW
2500
2000
High uptake
(residential and I&C)
1500
1000
Medium uptake
(residential and I&C)
500
0
2015
2020
2025
2030
Low uptake
(residential and I&C)
Figure 26: Average low frequency response from heat pumps to 2030
The response from heat pumps is very dependent on residential heat pump uptake. If only
commercial/industrial heat pumps are included, the response provided is 447MW in the
2030 Medium uptake scenario, 30% of the projected average primary response
requirement (for 2030 under the Gone Green Scenario). Retrofit installations in existing
housing of heat pumps with thermal storage for space heating (assumed in the analysis to
provide flexibility) may be challenging. If only heat pumps installed in new builds are
included, the response provided by them and industrial/commercial heat pumps in the
2030 medium scenario is 1472MW, slightly over 100% of the projected requirement.
33
Frequency Sensitive EV and Heat Pump Power Consumption
Final Report
Like for EVs, the potential high frequency response from heat pumps is lower than the
potential low frequency response. Figure 27 shows the amount of high frequency response
that heat pumps could provide out to 2030 for each of the three uptake scenarios. By
2030, heat pumps could contribute 1.3GW in the medium uptake scenario. This could
increase to 1.7GW of high frequency response in the high uptake scenario or fall to
196MW in the low scenario. Again, this is very dependent on residential heat pump
uptake, with only 16% of the response coming from commercial/industrial heat pumps in
the 2030 medium scenario.
Average high frequency response from HPs
1800
1600
High uptake
(residential and I&C)
1400
Medium uptake
(residential and I&C)
MW
1200
1000
800
Low uptake
(residential and I&C)
600
High uptake (I&C)
400
Medium uptake (I&C)
200
0
2015
2020
2025
2030
Figure 27: Average high frequency response from heat pumps to 2030
The above results assume that heat pump operation can be shifted by one hour. As
outlined in Section 3.2.2, there is significant uncertainty around this assumption. The
sensitivity of the results to this assumption was therefore examined. It was found that, for
the 2030 medium scenario, reducing this shift time to 30 minutes reduces the low
frequency response from heat pumps by 9%. Reducing the shift time further to 15 minutes
produces a reduction of 17% relative to the base 1 hour assumption. Thus, even with
much lower flexibility, heat pumps still have the technical potential to contribute
significantly to frequency response.
5.2.1 Seasonal variation in response
The analysis shows a significant seasonal variation in the response available from heat
pumps, with variations of approximately ±70% about the annual average. In the 2030
medium scenario, this corresponds to a minimum average low frequency response of
591MW in July and a maximum of 4.3GW in January. This means that in July, heat pumps
could meet only 40% of the projected primary response requirement (for 2030 under the
Gone Green Scenario) while in January they exceed it threefold.
The response from heat pumps changes over the course of the year because of the
variation in heat pump energy use (see section 3.2.1). Heat pumps use much less energy
in summer than in winter due to lower heating demands. This means that they are turned
on less often and at a lower power, which results in lower response availability.
34
Frequency Sensitive EV and Heat Pump Power Consumption
Final Report
To demonstrate the variation in response available from heat pumps over the course of a
given year, the 2030 Medium uptake scenario is taken as an example. Figure 28 shows
the monthly variation in average low frequency response from heat pumps in 2030 for
medium heat pump uptake. The seasonal change is very significant, with the response
available in January nearly five times that available in July.
Seasonal variation in average low frequency response from heat
pumps, 2030 medium scenario
5,000
MW
4,000
3,000
2,000
Commercial/Industrial
1,000
Residential
0
Figure 28: Monthly variation in average low frequency response from heat pumps, 2030
Medium scenario
It is also evident from Figure 28 that the bulk of response is provided by residential heat
pumps. On average over the year 82% of low frequency response is provided by
residential heat pumps while commercial/industrial heat pumps provide 18%. If residential
heat pump installations do not meet projected numbers, perhaps due to retrofit difficulties
or lack of consumer engagement, then the available response will be correspondingly
lower.
5.2.2 Diurnal variation in response
In the analysis, the response available from heat pumps also varies significantly
throughout the day. The available response is highest between 05:00 and 22:00, with an
early morning peak of 81% above the daily average. It is lowest during the night, at around
half the average response value. This means that in the 2030 medium scenario, during the
night heat pumps provide 50% of projected primary response requirements of the Gone
Green scenario while during the day they provide over 200% of the projected requirement
(see Figure 30).
To demonstrate this variation, we once again use the 2030 medium uptake scenario as an
example. Figure 29 shows the diurnal variation in average low frequency response from
heat pumps. This is calculated for each half hour over the whole year, and includes
response from residential and commercial/industrial archetypes. It shows that the
response peaks at 06:30 and is lowest between 23:00 and 04:00.
35
Frequency Sensitive EV and Heat Pump Power Consumption
Final Report
Diurnal variation in average low frequency response from heat
pumps, 2030 medium scenario
7000
6000
MW
5000
4000
Commercial/Industrial
3000
Residential
2000
1000
00:00
01:30
03:00
04:30
06:00
07:30
09:00
10:30
12:00
13:30
15:00
16:30
18:00
19:30
21:00
22:30
0
Figure 29: Diurnal variation in average low frequency response from heat pumps, 2030
Medium scenario
Figure 30 shows the percentage of National Grid’s primary frequency response
requirement (shown in Figure 17) that is satisfied on average by heat pumps throughout
the day. The diurnal variation in response availability is stronger than for EVs, so similar
measures will be needed to provide a constant response. As discussed in section 5.1.2,
aggregation with other types of demand side assets could provide a more constant
response capability. Alternatively, only baseload availability could be used and peak heat
pump response capability could be discarded so as to get a constant level of response
over the day.
300%
250%
200%
150%
100%
50%
22:30
21:00
19:30
18:00
16:30
15:00
13:30
12:00
10:30
09:00
07:30
06:00
04:30
03:00
01:30
0%
00:00
Percentage of requirements
satisfied by heat pumps
Diurnal variation in proportion of National Grid
requirements satisfied by heat pumps
Figure 30: Diurnal variation in how well heat pump response meets the National Grid Gone
Green scenario requirement, 2030 Medium scenario
36
Frequency Sensitive EV and Heat Pump Power Consumption
Final Report
6 Commercial potential
6.1 Costs of frequency response provision
The total cost to provide frequency response can be broken down into the individual asset
cost, including hardware and operational costs, and the business overhead costs for a
frequency response aggregator, as outlined in Figure 31. For the analysis it is assumed
that an SME is running a mature dedicated EV and heat pump frequency response
aggregation service. The analysis moreover assumes that hardware costs are integrated
in standardised products, which are manufactured at scale.
Figure 31: Breakdown of cost components for frequency response provision
The total annualised costs for the different archetypes are summarised in Figure 32.
The total cost per EV in the fleet EV archetype is about half the cost for the home charging
archetype, as the overhead costs are incurred per customer rather than per EV, and hence
these costs are shared between multiple EVs (the archetype assumes 10 EVs in a fleet).
For heat pumps most of the costs are incurred per heat pump. A commercial heat pump
typically has a significantly higher rating than a residential heat pump and hence the cost
per unit of power is 65% lower for the commercial heat pump archetype, compared to the
residential archetype (assumes commercial heat pump of size 10kW electric).
37
Frequency Sensitive EV and Heat Pump Power Consumption
Final Report
Annual costs of frequency response provision
£/asset/year
25
20
15
Business overhead cost
10
5
0
Home
charging
Fleet
EV
Residential
10kW
commercial
HP
Hardware and operational
cost
HP
Figure 32: Annual costs of frequency response provision by archetype
24
6.1.1 Individual asset cost
The cost per individual device includes hardware costs, consisting of a frequency sensor,
control equipment and metering and telemetry, and operational costs to cover
communications, data processing and maintenance. For industrial facilities, integrating
these components and controls into legacy systems can be technically challenging, and
the current retrofitted cost of these components for large industrial facilities is high. These
costs would be prohibitively high on a per customer basis for kW scale assets. However
cost estimates and interviews with aggregators and equipment manufacturers carried out
for this study indicate that these costs could be significantly lower for kW scale assets
when they are integrated into standardised products that are produced at scale, with
specifications to meet minimum requirements for frequency response services.
Hardware costs
EVs with mode 3 or 4 chargers already contain many of the required functionalities to
enable frequency response provision, although some additional hardware is required. The
additional required hardware to fully enable frequency responsive consumption consists of
frequency sensing, control, metering and telemetry components.
If these components are incorporated into standardised charge points that are produced at
scale, the additional costs could be approximately £10 (excluding engineering, design and
25
testing costs) per charge point . The specifications of this equipment are lower than for
currently used industrial versions, but are compatible with National Grid requirements,
providing frequency measurement with an accuracy of 1mHz, power metering with an
accuracy of 0.1% over a 2000:1 range of current and communications via WiFi. These
costs are per charge point, and hence are incurred fully for both home charging and fleet
EV archetypes, as it is assumed that each fleet EV has its own charge point.
24
Assumes fleet of 10 EVs and a commercial heat pump of size 10kW electric. Annual
cost calculated over 15 years.
25
Engineering cost estimate carried out for this study, based on quoted design
specification (see Appendix) and interviews carried out for this study. Costs for technical
components are for orders of 1000 or more. This does not include the engineering cost for
design and testing.
38
Frequency Sensitive EV and Heat Pump Power Consumption
Final Report
Heat pumps may require additional control equipment to be able to provide frequency
response. This additional cost is estimated to be £12-£25 per heat pump based on device
26
costs quoted in the Grid Scientific report for the CCC on the costs for residential DSR .
This cost assumption was confirmed in interviews with manufacturers. The costs are
assumed to scale with the size of the heat pump, and are therefore higher for larger
commercial heat pumps.
Enabling heat pumps to provide frequency response may furthermore require redesign for
most types of heat pumps to be able to provide frequency response in a reliable and safe
manner. These development costs are not included in the cost estimate.
Operational costs
Operational costs include communications, data processing and maintenance.
Communication costs are estimated to be approximately £5 per device per year, based on
analysis carried out in the Grid Scientific report for the CCC on the cost of domestic DSR
26
infrastructure . In the interviews carried out for this study, aggregators have indicated they
expect data processing could be brought down to a few pounds per device per year
(£3/device/year is assumed in the analysis). For annual maintenance cost a typical rule of
thumb of 3% of the initial hardware costs is assumed.
One of the main costs for conventional thermal generation in providing frequency response
is the opportunity cost incurred because of operating at part load. This cost includes
missed revenues and lower efficiency. The EV and heat pump archetypes considered in
this do not incur similar costs, which results in low costs for the provision of frequency
response. If EVs were to deliver electricity back to the grid, opportunity costs may be a
more significant factor (i.e. round trip efficiency, battery degradation). For other demand
response technologies, opportunity costs may also be relevant, e.g. lower efficiency in
industrial processes, interrupted production.
Business overhead costs
The business overhead costs for an aggregator of demand side frequency response
include establishing and operating a demand side response platform, billing systems, data
processing, legal and other back office staff costs, as well as marketing and sales costs.
These costs are to a large extent fixed costs, which scale stepwise with business size, and
hence per customer costs may be high for a small or start up business.
The overall business overhead costs are estimated to be £10 per year per customer. Over
half of this cost covers sales, marketing and customer retention, while 20% goes towards
initial set-up for new customers. The other 20% covers base IT systems costs, legal and
billing costs.
These costs are based on the analysis carried out by Grid Scientific for the CCC on the
26
cost of DSR infrastructure (assuming a small service provider with around 300,000
customers, limited service portfolio, either specialist or simple). This compares to the cost
of operating an electric vehicle smart charging service provider of £26/EV/year, as
26
Infrastructure in a low-carbon energy system to 2030: Demand Side Response, Grid
Scientific and Element Energy, 2013. Based on scenario for SME with less than 300.000
customers.
39
Frequency Sensitive EV and Heat Pump Power Consumption
Final Report
27
estimated in the Green e-Motion project . The overhead business costs are incurred fully
by residential EV or heat pump owners. Fleet operators or owners of large commercial or
industrial heat pumps incur the same annual costs, but due to the larger size of their asset
base, the cost per EV or per kW electric of heat pump power is relatively lower.
6.2 Revenues per archetype
National Grid’s total spend on frequency response services was approximately £150m in
28
2014 . As discussed in section 5, EVs and heat pumps have the potential to provide a
29
significant part of this market. Based on the current tendered prices , the annual average
potential in the 2030 medium scenario for EVs corresponds to approximately £66 million in
annual revenues, and £39 million for heat pumps (commercial and industrial).
The average Mandatory Frequency Response holding payments in 2014 were £10/MW/hr
for combined low and high frequency response provision, and rose to £20/MW/hr for FFR
28
for some periods . Although this represents relatively high revenues compared to other
DSR services, this value is diluted at an individual kW scale asset level. The total
revenues for the response provided by the different archetypes in the analysis are
summarised in Table 2, for a £10/MW/hr and £20/MW/hr price. These prices do not reflect
the fact that the higher responsiveness and accuracy of EV and heat pumps may reduce
the overall capacity requirement for frequency response, and hence the relative value of
30
these providers. For instance, in the US PJM pay-for performance frequency regulation
market, electricity storage providers are paid a price that is approximately 2-3 times higher
31
than conventional providers to reflect their fast response time .
Table 2: Revenues per EV or per heat pump for frequency response provision
Revenue per year,
Revenue per year,
£10/MW/hr payment
£20/MW/hr payment
Home charging EV
£46
£92
Work charging EV
£45
£90
Fleet EV
£46
£93
Residential heat pump
£72
£144
£23 per kW electric
£45 per kW electric
Industrial/Commercial heat
pump
For EVs, these revenues are calculated for BEVs and are expected to be slightly less for
PHEVs due to their 16% lower daily energy use. Implementing bi-directional charging may
increase the available response from an EV. However as discussed in section 3.1, this
may also increase battery degradation, increase energy losses due to round trip efficiency
27
Assuming a business with 50,000 customers, double the staff costs of the Spain case
example, 20% of staff cost for building and office costs, and 50% of staff costs for IT back
end, marketing and customer interaction. Green e-Motion Deliverable 9.4 Part 1,
‘Envisaged EU mobility models, role of involved entities, and Cost Benefit Analysis in the
context of the European Clearing House mechanism’, 2014
28
MBSS data and FFR post assessment tender reports 2014
29
Average £10/MW/hr for combined low and high frequency response provision
30
PJM is a Regional Transmission Organisation in the East of the USA.
31
PJM, Performance-based Regulation Market in PJM, July 2014. PJM, monthly average
regulation prices after introduction Pay for Performance (Oct 2012), 2011 – 2014
40
Frequency Sensitive EV and Heat Pump Power Consumption
Final Report
and poses higher operational challenges to ensure quality of service to the customer. For
an EV with bi-directional charging and a charge power of 3kW available over an 8 hour
charging period, the annual value would be approximately £90-£181/EV (for payments of
£10/MW/hr and £20/MW/hr respectively).
6.3 Cost benefit analysis
The analysis shows a net benefit in the provision of frequency response for all EV and
heat pump archetypes, summarised in Figure 33. While the system opportunity for this
type of response may be significant and the cost of providing frequency response may be
very competitive compared to conventional thermal plants, the potential net benefit on an
individual asset level is diluted significantly.
Annualised cost benefit per archetype
Home charging EVs
Residential heat pump
£/yr
Fleet EV
£/yr
£/yr
10kW commercial heat pump
£/yr
Figure 33: Cost benefit analysis by archetype, all in £/year
32
Figure 33 shows the net annual benefit for different EV and heat pump archetypes. For
EVs the net benefit is highest for the fleet EV archetype, as business overhead costs are
shared between EVs. The net benefit of a home charging EV is lower at £26 per year;
however this represents a saving of approximately 9% of a typical annual EV electricity
32
Assumes a fleet of 10 EVs and a commercial heat pump of size 10kW electric. Annual
cost calculated over 15 years. Revenues are for BEVs and are expected to be around 16%
lower for PHEVs.
41
Frequency Sensitive EV and Heat Pump Power Consumption
Final Report
33
bill . This diluted value will require efficient commercial models for the deployment of EVs
in frequency response services.
The net benefit of a residential heat pump is almost double that of a home charging EV.
34
This represents a saving of approximately 9% of a typical annual electric heating bill .
Similar to EVs, the net benefit per unit is higher for commercial heat pumps due to their
larger size. However hardware modification costs for commercial heat pumps may be
higher due to the fact they are more integrated in building systems, bespoke and have
lower productions (these aspects are not taken into account in the cost estimate).
6.4 CO2 emissions impact
Frequency sensitive energy consumption by EVs and heat pumps does not result in
additional carbon emissions, as the total energy used remains unchanged. Frequency
response from EVs and heat pumps therefore has the potential to avoid carbon emissions
by conventional providers of dynamic response.
Compared to conventional thermal generation, dynamic frequency response by home
charging EVs has the potential to offset around 1 tonne of CO2 per EV per year. Similarly
dynamic frequency response by heat pumps has the potential to offset around 0.6 tonnes
of CO2 per kW per year for commercial heat pumps and around 2 tonnes of CO2 per year
for residential heat pumps.
Most dynamic response is currently provided by coal and gas fired power plants, in similar
35
amounts . For these plants, holding capacity available so as to provide frequency
response results in lower efficiency and hence an increase in CO2 emissions of
36
approximately 10% . This results in an average increase in emissions of 0.26 tonnes of
37
CO2 per MWh of response held . Table 3 shows the potential CO2 emissions that could be
avoided by EV and heat pump archetypes by replacing conventional thermal generation
for dynamic frequency response.
33
Assumes EV electricity bill of £300/year (10,000 miles at 3p/mile)
Assumes heat pump electricity bill of £550/year (15kWh consumption per day, with
electricity price of 10p/kWh)
35
National Grid, BM unit Mandatory response Holding Volumes, 2013
36
When operating at 80% part load, Sources: (i) Short Term Operating Reserve – Carbon
Intensity Report (ii) Appendix B, SQSS Review Request GSR007 Amendment Report,
National Grid, SP Transmission and SSE, September 2009
37
80% part load, produced at 10% lower efficiency. Gas-fired power plant: 10% additional
emissions x 80% part load x 0.4T CO2 per MWhe = 0.16 T CO2 per MWh response
holding. Coal power plants: 10% additional emissions x 80%part laod x 0.9T CO2 per
MWhe = 0.36 T CO2 per MWh response holding
34
42
Frequency Sensitive EV and Heat Pump Power Consumption
Final Report
Table 3: CO2 emissions avoided per year per EV or heat pump archetype for
dynamic frequency response provision
Carbon emissions
avoided (Tonnes
CO2/year)
Home charging EV
1.20
Work charging EV
1.17
Fleet EV
1.20
Residential heat pump
1.87
Industrial/Commercial heat
pump
0.60 per kW electric
6.5 Commercial models
Commercial models exist to enable third party assets to contribute to National Grid’s
management of the electricity system. The commercial models that are used need to be
able to deliver sufficient resources to meet National Grid’s needs in a cost effective
manner for consumers.
Current procurement of frequency response (both mandatory frequency response and
38
FFR) has been developed for a system in which conventional generation facilities
provide most of the required response. FFR contracts also provide a route to market for
frequency response from distributed demand side resources by aggregators. Moreover,
novel products such as the FFR bridging contract, aim to increase market access for
demand side participation.
Current frequency response products and contractual conditions have however not been
developed particularly for novel distributed demand side opportunities. Highly responsive
demand side assets may be able to provide more effective response when these
conditions are adapted. Moreover current conditions are not set up for the particular
requirements of these resources, such as the impact of the large number of small assets
on telemetry and verification, diurnal variability, predictability and in the short term
minimum capacity.
ENTSO-E and European TSOs are exploring the option to mandate frequency sensitive
electricity consumption for thermostatically controlled appliances, such as heat pumps.
This mandatory requirement would be taken up in Demand Connection Codes (DCC) and
implemented through EcoDesign standards.
6.5.1 Key commercial models
In the following reviews we distinguish between three high level commercial models, as
summarised in Figure 34. This distinction is based on two key aspects. The first aspect is
38
Comprising e.g. large synchronised thermal generation, pumped hydro storage,
embedded generators
43
Frequency Sensitive EV and Heat Pump Power Consumption
Final Report
whether frequency response is provided through a commercial procurement process, or
mandated. The second aspect is a distinction between more conventional firm capacity
39
contracts and more dynamic capacity contracts .
Firm commercial procurement
Current FFR contracts are an example of firm capacity contracts. In this model response
capacity is bid well in advance with a fixed capacity over the bid window. Reliability and
accuracy conditions are usually defined as static minimum requirements. These contract
conditions have typically been developed for response provision by large conventional
generation.
Dynamic commercial procurement
Dynamic capacity contracts may differ from firm capacity contracts on a number of
aspects. They may allow profiled bids (with varying capacity nominations for different time
periods), short lead times to nomination or ability to adapt capacity nominations close to
delivery time, and lower minimum capacity requirements. Another key aspect may be
remuneration based on effectiveness and performance, rather than setting minimum
requirements.
Mandatory frequency response
A third option is the introduction of mandatory frequency responsive consumption.
ENTSO-E and TSOs are currently reviewing the option to mandate frequency responsive
consumption for thermostatically controlled devices. An alternative option is to mandate
the technical capability, but implement a commercial procurement model.
The following sections will review the key barriers for the development of demand side
frequency response services, and compare how these are addressed in the different
models.
High minimum capacity
requirements, fixed
capacity bids, long lead
times for nomination,
minimum accuracy and
reliability requirements
Low minimum capacity
requirements, profiled
bids, short lead times to
nomination, remuneration
based on effectiveness
and performance
Commercial procurement
Firm
requirements
Dynamic
requirements
Mandatory
Firm commercial
procurement
Dynamic
commercial
procurement
Mandatory
frequency
response
Figure 34: High level summary of potential commercial models
39
This is separate from the FFR distinction in static and dynamic frequency response.
Current FFR services are both classed as “firm capacity contracts” in this review.
44
Frequency Sensitive EV and Heat Pump Power Consumption
Final Report
6.5.2 Key barriers and advantages for three commercial models
Technical aspects
The available EV or heat pump response capacity may vary significantly within a
day.
40
Current FFR bids are typically for a fixed capacity per period , while the available
response from EVs and heat pumps may vary significantly throughout the day.
Firm commercial procurement
 Aggregators are responsible for providing firm capacity bids to National Grid.
 As a result not all EV and heat pump potential response capacity may be utilised.
Dynamic commercial procurement
 Could allow more flexible bids, for instance supporting profiled bids for varying
capacity throughout the day.
 As a result the potential response from EVs and heat pumps may be more fully
utilised, but increases operational challenge for National Grid.
Mandatory model
 All available response capacity at any one time is utilised by default as first option.
 National Grid may have limited visibility of the response capacity that will be
available. There is also no mechanism to guarantee that the mandatory response
is the lowest overall system cost option.
41
A large portfolio of small demand assets provides reliability through diversity ,
which is different from the reliability provided by individual large assets.
When a single large provider of response is unexpectedly not available this has a large
impact on the total available response, and hence National Grid places reliability
requirements on response providers. However a large fleet of small demand assets
provides reliability through diversity. Even when the contracted amount is not provided due
to failure of some assets, the total response from that portfolio of assets at any given time
may still be close to the total contracted response, limiting the impact on the total response
availability.
Firm commercial procurement
 Typically have high static reliability requirements, risk of meeting these lie with
aggregator.
 As a result not all EV and heat pump potential response capacity may be utilised.
Dynamic commercial procurement
40
Typically whole day, or 07:00 to 11:00 and 11:00 to 07:00. Bids for any time frame can
be placed, however this is not common practice and National Grid will moreover assess
each bid individually.
41
This refers to the inherent portfolio reliability due to the fact that failure of assets is likely
to be uncorrelated. In other words, a few assets failing at any given time will have a small
impact on overall available capacity if they are part of a large portfolio, and so the overall
portfolio reliability is likely to be higher than the individual reliabilities of each of the assets.
45
Frequency Sensitive EV and Heat Pump Power Consumption
Final Report


May be structured to utilise diversified reliability more effectively, using staggered
reliability requirements or performance based remuneration.
May require National Grid to develop new tools to assess overall response
reliability.
Mandatory model
 Diversified reliability can similarly be utilised.
 Places a larger responsibility on National Grid to assess the mandatory reliability
and residual response requirements.
Available response capacity from demand assets is more unpredictable the longer
the forecast horizon, depending on external influences.
The available response capacity from demand assets may depend on external influences,
for instance outside temperature for heat pumps. The accuracy of available response
forecasts depends on the forecast horizon. This may result in not all EV and heat pump
potential response capacity being utilised.
Firm commercial procurement
 Available capacity needs to be forecast well in advance and turn out capacity may
differ.
 As a result not all EV and heat pump potential response capacity may be utilised.
Dynamic commercial procurement
 May be designed to allow shorter lead times for nomination of available capacity
or allow bid capacities to be adapted closer to time of delivery.
 May result in more residual response capacity instructed by National Grid to be
available at shorter notice.
Mandatory model
 All response capacity is used as it is available.
 Requires National Grid to develop tools and processes to forecast mandatory
response levels, and more instruction on short time scale to other providers of
response to be available.
Operational aspects
A high overall uptake or local EV and heat pump clustering may require active
management of response settings.
When demand assets contribute a significant part of total frequency response capacity and
their response characteristics are highly correlated, this may result in dynamic frequency
stability issues. This is especially the case when assets turn on again simultaneously after
a low frequency event. Similarly local distribution network issues, e.g. voltage stability and
harmonics, could arise with high local clustered uptake, even when overall uptake is not
yet high. This may require active management of the assets to ensure a stable response,
or diversification of individual asset response characteristics.
Managing and diversifying response characteristic may be more readily done by
aggregators in commercial procurement models, than by National Grid in a mandatory
46
Frequency Sensitive EV and Heat Pump Power Consumption
Final Report
model. Aggregators have a commercial relation with individual providers, and this could be
implemented as a precondition to participating.
Provision of frequency response by demand assets could change consumption
profiles, potentially increasing imbalance.
For EVs and HPs, implementing frequency sensitive charging may impact the overall
consumption profile. When uptake of demand side frequency response increases without
visibility for suppliers, this may result in deviations in the Non Half Hourly (NHH) demand
curve from what the suppliers expect. This could pose problems for suppliers in
settlement, potentially increasing system imbalance and balancing costs.
Although modified settlement configurations can be developed, this is complicated in
commercial models if the aggregator is a different entity from the supplier of the consumer.
The supplier may not have visibility of third party contracts and impacts or contract
changes of a consumer.
The impact in future Half Hourly (HH) settlement will depend on how this is implemented
(aggregated or individual settlement). Suppliers may experience increased imbalance
positions if similarly the aggregator is another third party and the supplier does not have
visibility of frequency response contracts and impacts.
Reduced diversity and correlated response to frequency deviation events may
result in thermal and voltage issues in already strained distribution network areas.
Clustered provision of frequency response by demand assets may reduce the diversity of
electricity consumption, especially with correlated consumption increase after a frequency
deviation event. This may result in thermal constraints and voltage increases in already
strained distribution network areas. This may require coordination with DNOs to provide
transparency of demand side frequency response providers, and limitations or
diversification of response in already strained areas.
Commercial procurement
 May provide additional complexity, needing to develop processes involving the
TSO, DNOs and commercial parties (aggregators, suppliers).
 May reduce the overall required capacity for frequency response and increase
incentives for consumer to participate.
Mandatory model
 Can be resolved between the TSO and the DNO, without third parties.
 Does require National Grid to develop control systems to manage this.
Commercial aspects
Ability of electrical equipment to provide rapid and accurate response provides
higher effectiveness in arresting and restoring frequency deviations than
conventional mechanical response providers.
Firm commercial procurement
47
Frequency Sensitive EV and Heat Pump Power Consumption
Final Report


Current firm response contracts do not specifically remunerate fast response
capabilities or accuracy of response, beyond minimum reliability requirements.
Although providers could tender with higher response characteristics, National
Grid does not currently have a process in place to value faster response.
Dynamic commercial procurement
 Could be designed to remunerate on the basis of delivered response speed and
accuracy, similar to pay-for-performance frequency regulation in e.g. the US PJM
market.
 May reduce the overall required capacity for frequency response and increase
incentives for consumer to participate.
Mandatory model
 Setting of minimum requirements is likely to be required.
 May not incentivise the development of faster and more accurate response
capabilities.
Demand assets are suited to provide other DSR uses as well
Demand assets could be used for a wide range of other DSR uses in addition to frequency
response. Stacking different DSR uses increases the effective use of assets, reduces
overall system cost and may increase the value of propositions for consumers,
encouraging a greater uptake of DSR.
Commercial procurement
 May support the integration with other DSR uses by aggregators.
Mandatory model
 May reduce the ability of aggregators to bundle different DSR uses and may
reduce the overall attractiveness of customer propositions, dis-incentivising the
uptake of DSR. This may be addressed by larger local DSR coordination role by
DNOs.
Frequency response provision may represent only limited value on an individual
asset basis
The analysis shows there is a significant system benefit for EV and heat pump frequency
response. However this opportunity represents a limited value at an individual asset level.
Uptake of this opportunity can be supported by efficient commercial models or through
mandating. As discussed in section 6.1 a cost effective implementation of frequency
response in equipment requires standardised integration of additional components in
charge points and heat pumps. Although the cost of doing so at scale may be relatively
limited (of the order of £10 per device) initial implementation is likely to be more expensive
and also comes with significant development costs. This requires either confidence in a
market for technology developers or mandating this capability in design standards or
demand connection codes.
Commercial procurement
48
Frequency Sensitive EV and Heat Pump Power Consumption
Final Report
May allow the potential response from demand assets to be utilised more effectively
especially, as discussed in the previous paragraphs by;
 Accommodating the specific characteristics of demand assets and providing
equitable remuneration based on performance.
 Enabling aggregators to combine the provision of frequency response with other
DSR uses, lowering the business and operational overhead costs per service and
increasing the value of customer propositions, which may increase participation
levels
Mandatory model
Enabling uptake despite diluted value at an individual level may also be supported through
mandating frequency response;
 As discussed in the previous paragraphs, key challenges include that it may not
unlock the full potential, and may limit the ability of third parties to also provide
other DSR uses using the same assets.
 A mandatory scheme may include remuneration of consumers, which may depend
on whether the costs of administering such remuneration would outweigh benefits
to consumers.
6.5.3 Commercial model conclusion
The analysis shows a clear system benefit of frequency response from EVs and heat
pumps, but the value is diluted on an individual asset level. Unlocking the opportunity that
EVs and heat pumps present requires efficient commercial models, or, alternatively,
mandatory provision. A qualitative comparison of the different models for EVs and heat
pumps is explored in more detail in section 8.2.
Commercial procurement models, especially dynamic models, may unlock a high
response from individual assets and support the integration by aggregators with other DSR
uses, increasing the attractiveness of propositions to consumers. Dynamic commercial
procurement moreover most readily allows innovative development of more effective
frequency response from demand assets. Commercial procurement models moreover
provide the closest fit with current National Grid practices and processes. This however
does not provide guarantees on overall uptake.
Compared to current Firm Frequency Response contracts, dynamic contracts could
support the potential and value of EV and heat pump frequency response by enabling;





Profiled bids
Adaptation of reliability requirements to reflect diversified reliability
Shorter lead times to nomination of capacity
Utilisation of fast and accurate response capabilities, and provision of equitable
remuneration for these capabilities
Integration with other DSR services by assets.
A mandatory model on the other hand provides a high guarantee on the overall uptake.
However it may not unlock the full potential of individual assets, and may inhibit the
integration with other DSR uses and the development of novel deployment models. It
would moreover require National Grid to develop new tools and practices to manage
49
Frequency Sensitive EV and Heat Pump Power Consumption
Final Report
frequency response provision from demand side assets. Difference in individual response
constraints and contributions may also lead to issues of fairness. Differences are
especially prevalent with EVs where response availability depends on driving and charging
practices.
In either case, active management of response settings will be required to avoid network
issues associated with a reduction in diversity. Also, possible impacts on aggregate
demand profiles and hence supplier imbalance must be addressed.
50
Frequency Sensitive EV and Heat Pump Power Consumption
Final Report
7 Technical barriers and challenges
The literature review and stakeholder interviews for this study indicate that there are no
fundamental technical constraints to provide frequency response using EVs or heat
pumps. However, both require further technical development in a number of areas, and
specific technology characteristics may impact the extent of their capability to provide
frequency response. In the analysis we distinguish between four key areas that may
present technical challenges and barriers to enabling frequency response from EVs and
heat pumps:
1.
2.
3.
4.
Hardware capability
Control & automation
Telemetry and verification
Operation and network impacts
These are discussed for both EVs and heat pump in the following sections.
In this analysis it is assumed that frequency response capability is implemented in a
similar way to today’s providers. The components of such a system are outlined in Figure
35. In this setup, assets are equipped with frequency sensors to measure system
frequency locally. This signal is used in the local control unit, alongside user inputs (such
as desired temperature or time by which charging needs to be complete) and frequency
response characteristics (which may be controlled remotely), to manage charge and
consumption rates. A third party, for example an aggregator or National Grid,
communicates with the control unit to adapt response characteristics and monitor
electricity consumption.
An alternative approach would be for aggregators to measure system frequency centrally
and instruct assets to respond. Such a setup would however increase response times, due
to central computation time and delays due to two way communication necessary to
instruct assets to respond. Another possibility is for National Grid to broadcast a regulation
signal, which is based on the system frequency. This approach is used in the US PJM
market.
51
Frequency Sensitive EV and Heat Pump Power Consumption
Final Report
Figure 35: Components necessary for frequency response provision by EVs and heat
pumps with the corresponding data flows
7.1 Electric Vehicles
7.1.1 Hardware capability
There are no fundamental technical barriers to EVs providing frequency response and no
hardware changes to the EV itself are required. The EV battery provides energy storage
and charge power can be reduced or interrupted without significant adverse effects.
Battery technology is particularly well suited to providing response because of the speed of
the power electronics that regulate charging. The response time of EVs to a control signal
is approximately 1 second, making them suitable for provision of very fast frequency
response services. The IEC 61851 standards for EV charging require that the car battery
responds to a control signal within 5 seconds, while in practice response times are much
less.
7.1.2 Control and automation
Typically, EV charge points do not currently include the components necessary for
frequency response provision and would therefore require a design update. Including
frequency responsive capability in the design of a charge point would be relatively
straightforward. However, retrofitting this capability in already installed charge points would
be challenging due to the difficulty in physically fitting the components required and in
integrating the functionality with existing hardware and software. Therefore, early update of
charge point design would be necessary to prevent high uptake of unsuitable equipment.
Some charge points, mainly higher specification mode 4 DC units, may already have the
required frequency measurement, metering and telemetry capability and so may only need
52
Frequency Sensitive EV and Heat Pump Power Consumption
Final Report
a software update in order to implement frequency response. However, most mode 3 AC
charge points do not currently measure frequency or have sufficient power metering.
Communications and remote control capability is also currently limited, with low data
transfer rates and only crude on/off remote control possible.
One practical issue raised by stakeholders is the fact that there is currently no
communication standard for the EV to notify the charge point of its state of charge (SOC).
Such a standard would need to be developed in order to ensure that the charge point is
aware of the EV charging requirements, and can therefore manage the charging without
any negative impact on the driver. This is particularly an issue for AC charging, as for DC
charging, there is often more communication between the car and the charge point.
Also, the impact of frequency response on charging management will not necessarily be
well defined in all cases. For example, a sudden reduction in charge power may be
interpreted by some EVs as an error condition and result in a shut down. These aspects
will need to be examined in trials in order to fully characterise the impact on EVs of varying
charge power in response to grid frequency.
7.2 Heat Pumps
7.2.1 Hardware capability
There are no fundamental barriers for heat pumps to provide frequency response, though,
unlike for EVs, there are hardware issues to resolve.
The most fundamental design concerns are around the speed of heat pump response.
Heat pumps do not respond as quickly as EVs or other electric devices because in order to
make changes to the compressor speed, a mechanical adjustment must be made. While
turning off the heat pump would be near instantaneous (on the order of ms), increasing the
power draw takes tens of seconds, or even minutes, according to manufacturers. This is
because adequate lubrication of the compressor and general system stability must be
ensured. Variable speed heat pumps, which represent the majority of models currently on
the market, may also ramp down slowly so that control is smooth, though this is not a
fundamental need and could be overridden. These issues can be addressed in periodic
redesign of heat pumps, especially given that this is still a nascent market, but require a
driver for manufacturers to do so.
A key requirement for heat pumps providing frequency response is the presence of
thermal storage. The volume of thermal storage available is uncertain, though, as
discussed in section 5.2, even with limited thermal storage heat pumps could still
contribute significantly to frequency response provision.
The expected impact of frequency responsive control on heat pump lifetime and efficiency
depends on the type of heat pump and the control strategy implemented. The number of
42
heat pump stop/starts should be limited to six per hour , and, in general, according to heat
pump manufacturers, varying power is preferable to on/off control. This implies that
variable speed heat pumps are more suited to providing response, though issues around
the speed of response, discussed above, require real world investigation.
42
This is based on interviews with heat pump manufacturers and on the 2012 EA
Technology report, ‘The Effects of Cycling on Heat Pump Performance’.
53
Frequency Sensitive EV and Heat Pump Power Consumption
Final Report
Large industrial or commercial heat pumps will have more site specific flexibility and
hardware characteristics and may therefore need bespoke assessment to see if they can
provide frequency response.
7.2.2 Control and automation
Generally, heat pumps do not currently have all the components required to provide
frequency response. The integration of these features into the complex control system of
the heat pump and the existing Building Energy Management System (BEMS) may entail
higher costs than for EVs. However, for residential heat pumps, much of the hardware
capability, with the exception of the frequency sensor, may become standard in the near
term. Heat pumps are expected to have internet connectivity, power metering (which,
without a clear driver, may not satisfy National Grid’s requirements) and the ability to
respond to external control signals.
Other features, which may enhance the ability to provide frequency response, are currently
in development. These include self-learning capability, whereby the heat pump would learn
the thermal response of the house and the typical user behaviour, thus enhancing
predictability and reliability of response, as well as user comfort.
For commercial and industrial heat pumps, there is typically already significant monitoring
via the BEMS, so these may already have the required metering capability. However, they
may not be connected to the internet and may only have crude control capability, in which
case additional hardware would still be required to provide frequency response.
7.3 Verification and telemetry
A number of stakeholders interviewed for this study indicated that verification
requirements, and clarity in how metering and verification is reported to National Grid, are
a key issue in the next steps to develop demand frequency response provision.
A first aspect is the baseline methodology that is used to determine the amount of
response that is provided (response traces compared to counterfactual trace). Developing
this methodology early on allows developers to trial under conditions that will be the same
in commercial operation and provides transparency of the impact on future business
cases.
A second aspect is the data evidence that needs to be provided to National Grid. Current
FFR providers are required to provide evidence of response provided for each individual
asset. This can be done by providing real time second-by-second data or real time minuteby-minute data with subsequent second-by-second data after an event. For demand side
participation it will be similarly critical to verify response and guarantee reported response
levels are accurate. National Grid is likely to only require real time data on an aggregator
level, rather than individual asset level, with individual asset data retained for later
verification or auditing. In some trials response verification was carried out based on
metering a sample of the participants and extrapolating total response from that, mainly
because of high costs. For a business as usual service this is not seen as a likely option
for National Grid. This does imply that aggregators need to collect real time data from
individual assets. This has implications for potential telemetry options, as discussed below.
The real time data exchange and instruction signals requires a telemetry system with high
bandwidth and low latency, separate from the smart meter. The most cost effective and
54
Frequency Sensitive EV and Heat Pump Power Consumption
Final Report
readily available option is to use a broadband connection, possibly combined with local
wireless mesh to connect multiple devices for fleet operators. Of the different wireless
mesh options WiFi provides a higher bandwidth compared to alternatives (e.g. ZigBee or
43
ZWave ). Another option would be to use the licenced cellular network (e.g. GPRS, 4G,
5G), however this is significantly more expensive than broadband. Other technologies are
also emerging that use the unlicensed part of the network, however these have typically
low bandwidths. A fourth option may be to use power line communications.
Currently there is no standardised protocol for communication between charge points or
home and energy management systems, and aggregator management systems. Many
proprietary protocols have been developed. Open protocols have also been developed,
notably for EVs the Open Charge Point Protocol (OCPP), developed by E-Laad and
supported by a range of other stakeholders. A challenge for open protocols is to enable
more extensive functionalities, such as required for frequency response. Proprietary
protocols can more readily be adapted to enable more extensive functionality.
7.4 Network impacts and system operation
Transmission network
With large scale uptake, correlated responses from similar demand assets may result in
system frequency oscillations. This can be addressed in control design of response
settings. In order to provide this, aggregators need to be able to adjust and vary asset
response characteristics; including the ability to put assets in and out of frequency
sensitive mode, set dead band levels, and adjust dynamic response functions (hysteresis,
droop curve). With a large number of kW scale assets, this likely requires management
and communication systems between National Grid and aggregators, and between
aggregators and assets, with more advanced capabilities than currently employed for
instance in aggregating embedded generation. This issue may be especially challenging in
a Mandatory Frequency Response model. With low uptake these impacts can be absorbed
by other assets, but it may require more active control management when demand assets
provide a significant part of the total response.
Distribution network
Clustered uptake of frequency response by EVs and heat pumps may result in a significant
reduction in demand diversity, especially with correlated consumption increase of demand
response providers after a frequency event. DNOs interviewed for this study do not expect
this to be an issue for most parts of the distribution network. However, for some local
network areas that are already strained, this may result in various issues including:


Voltage stability (voltage drop and rise); this may happen especially in areas that
are net generation.
Thermal overloads of transformers; analysis carried out in the Green Motion
project for non-diversified ToU tariffs indicates that this may result in overloaded
43
These are protocols to create local networks, often used for applications such as home
automation.
55
Frequency Sensitive EV and Heat Pump Power Consumption
Final Report

transformers in substations in some network areas, while in other network areas
44
such issues will not occur .
Harmonic emissions; these could increase (especially if charge rates are
modulated in EVs with lower performance inverters), requiring DNOs to take
countermeasures (e.g. filters). For modern inverters this is not expected to be a
fundamental issue, but should be addressed by OEMs and charge point
45
manufacturers in design of inverters .
This is similar to effects that may happen with non-diversified Time of Use (ToU) tariffs in
areas of high EV uptake. Addressing these issues requires a process to be in place
between DNOs and National Grid to identify where clustered uptake may result in issues
on the distribution network. By extension this requires National Grid to have visibility of the
location of aggregated response and a system to reject providers in some areas or instruct
aggregate response characteristics in collaboration with DNOs. This further increases the
complexity of management and communication systems for a large number of kW scale
assets contributing to frequency response, as discussed in the previous section.
Where EVs or heat pumps providing frequency response are part of a DNO Active
Network Management (ANM) system, there is a risk that the ANM system negates
frequency response actions. This similarly requires transparency of location of response
providers between DNOs and SO.
On a very localised level, rapid switching of large loads such as EVs and heat pumps for
frequency response may result in transient effects such as flicker. Flicker is caused by
rapid fluctuations in the voltage of the power supply and results in visible dimming
oflighting, hence its name.
8 Roll Out
The previous sections analysed the EV and heat pump technology aspects for enabling
frequency response, the potential impact on other stakeholders, the benefits and costs,
and outlined the possible commercial models. Figure 36 outlines the main elements in the
roll out of EV and heat pump frequency response, and the key barriers for each are
summarised in the following sections.
Section 8.2 than reviews the relative merit of commercial procurement or mandating for
frequency response from EVs and heat pumps. The last section identifies the key next
steps that National Grid may take to develop these opportunities and where collaboration
with other stakeholders may be required.
44
Green eMotion, Recommendations on grid-supporting opportunities of EVs, 2012
Dansk Energy, Green eMotion grid impact studies of electric vehicles – EV’s impact on
Power Quality related to harmonics, 2013
45
56
Frequency Sensitive EV and Heat Pump Power Consumption
Final Report
Development of EV and heat pump frequency response
Commercial market development
1. Strategic agenda & business case
2. Enabling deployment
3. Market access
Impact on other stakeholders
1. Power quality (DNO)
2. Thermal overload and voltage stability
3. Settlement and supplier balance
Technology and proposition development
1. Hardware capability
2. Control & automation
3. Telemetry and verification
4. Delivery model
Figure 36 Key components in frequency response service development: commercial
market, impact on other stakeholders and technology and proposition development
8.1 Summary of key barriers for the development of EV and
heat pump frequency response
8.1.1 Commercial market development
1. The analysis shows that both EVs and heat pumps may be able to provide a
significant part of National Grid’s frequency response needs by 2030, and may be
cost effective compared to incumbent providers. The value at an individual asset
level is however relatively low. This provides limited incentives to develop these
opportunities, which require investments in further development of EVs and heat
pumps, communications and telemetry, as well as in business models and
management systems.
2. Bilateral contracts may provide a route to market for providers that can’t meet
regular FFR requirements and can provide National Grid unique or novel response
capabilities. However the technical requirements, service conditions, verification
57
Frequency Sensitive EV and Heat Pump Power Consumption
Final Report
processes and baseline methodology for aggregated small scale demand
providers are not clear.
3. There is currently no market or future framework for the provision of frequency
response from large fleets of kW scale EVs and heat pumps, which have different
characteristics and capabilities compared to conventional synchronised
generators. Fast and accurate responding demand assets may moreover be of
increasing value in helping to manage system frequency, reducing the overall
need for frequency response. A review of contractual terms and conditions may be
required to utilise the potentially more effective system frequency management
capabilities, and accommodate specific reliability and availability characteristics.
Also, a large number of kW scale assets providing frequency response may have
local network and system impacts, as discussed in section 7.4. Mechanisms will
need to be put in place to address these impacts.
8.1.2 Impact on other stakeholders
1. Clustered uptake of frequency responsive EVs may increase emissions of
harmonics into the distribution network (stakeholders: SO, DNOs, equipment
manufacturers, aggregators). Rapid switching of EVs and heat pumps for
frequency response may introduce flicker (stakeholders: SO, DNOs, equipment
manufacturers, aggregators).
2. Clustered uptake of frequency responsive EVs may result in thermal overload or
voltage stability issues in some distribution network areas (stakeholders: SO,
DNOs, equipment manufacturers, aggregators).
3. High uptake of frequency responsive EVs and heat pumps may impact the
accuracy of SSCs and system imbalance for NHH settlement, if suppliers are not
the frequency response aggregator and do not have visibility of response provision
impact. Similarly for HH settlement lack of visibility may increase supplier
imbalance. (stakeholders: SO, aggregators, suppliers, Elexon) .
8.1.3 Technology development
1. For EVs further technology development may be required, especially interaction
with safety measures and emission of harmonics into the distribution network. For
heat pumps further technology development is required, especially to support
higher ramp rates or stable and safe interruptions.
2. EV charge points (especially AC charge points) and heat pumps do not currently
include the components necessary to support frequency response and would
therefore require a design update. Moreover there are no widespread
standardised communication protocols between vehicles and charge points that
support all required functionality.
3. Currently there is no standardised protocol for communication between charge
points, heat pumps, and aggregator management systems that are interoperable
and support frequency response requirements.
4. Especially for EVs, most stakeholders are currently focused on developing
charging infrastructure and basic smart charging management (e.g. peak load
reduction to reduce wholesale purchase cost, network and connection charges,
Renewable Energy Sources integration). The development of frequency
responsive capability and of communication and interoperability standards to
support this may not be prioritised by commercial parties. This may mean that
technologies (EVs and charge points) are being developed for large scale
58
Frequency Sensitive EV and Heat Pump Power Consumption
Final Report
deployment, without integrating the capabilities required to provide frequency
response, risking that early large scale deployments will not be able to provide
such services or only at high retrofit cost.
8.2 Comparison of commercial procurement and mandatory
provision
National Grid currently procures all frequency response services on a commercial basis.
However all generators caught by the requirements of the grid code are mandated to have
the capability to provide frequency response.
The analysis shows a clear system benefit of EV and heat pump frequency response, but
it is unclear if the diluted value at an individual asset level will be sufficient to develop
these opportunities. Developing these opportunities can be realised either by supporting
early developments in a commercial procurement model or mandating the provision of
frequency response. Section 6.5 provides a high level outline for commercial and
mandatory models, and discusses how they impact the key barriers for the uptake of
frequency response from EVs and heat pumps. The following sections provide a
qualitative comparison between commercial and mandatory models for frequency by EVs
and heat pumps respectively.
8.2.1 EVs
The comparative analysis summarised in Table 4 indicates that a commercial procurement
model for EV frequency response may be most appropriate;




Although the value at an individual asset level is diluted, third parties are already
developing smart charging propositions that may be extended to include frequency
response. Combining revenues from different DSR uses and utilising a shared
platform may increase the value of a proposition to customers and support uptake
of frequency response. Mandated frequency response may limit other DSR
opportunities and limit the overall value of propositions.
The analysis shows that the system benefit of frequency response from EVs may
be higher when combined with controlled smart charging; mandatory frequency
response does not readily support this development.
The potential and value of frequency response from EVs may potentially be
increased by enabling bi-directional charging for frequency response. However
enabling this may require significant technology development and mandatory
frequency response may reduce the driver to do so.
EV availability for frequency response does not only depend on instantaneous
parameters, but may depend on consumer future constraints (e.g. required SOC),
this may be challenging to accommodate in a mandatory model.
However, most stakeholders are currently focused on developing charging infrastructure
and basic smart charging management (for example connection capacity management,
peak shifting, local renewable integration). The development of frequency responsive
capability and of communication and interoperability standards to support this may not be
prioritised by commercial parties. This may mean that technologies (EVs and charge
points) are being developed for large scale deployment, without integrating the capabilities
59
Frequency Sensitive EV and Heat Pump Power Consumption
Final Report
required to provide frequency response, risking that early large scale deployments will not
be able to provide such services or at high retrofit cost.
This may provide a rationale to mandate the capability to provide frequency response. EV
deployments currently receive heavy public financial support (subsidy for the installation of
charge points and EV subsidy plug-in Car Grant). This provides an opportunity to require
supported technologies to be frequency response capable, to implement interoperable
communications, to adhere to standards (such as ISO 15118) and consider impacts on
power quality in design. This would reduce barriers and limit incompatibility for subsequent
development of frequency response services.
Table 4 Summary qualitative comparison mandatory and commercial model for EVs
Green = Very high compatibility with model
Yellow =
High compatibility with model
Orange =
Low compatibility with model
Red = Very low compatibility with model
EVs
Mandatory Commercial
System potential
System cost
effectiveness
Individual asset
incentive
Consumer quality of
service impact
High system potential
Cost
effective
incumbents
compared
to
Limited individual asset value
Challenging to manage
Variation in impact
across consumers
Very different, depending on
driving patterns, charge location,
preferences and EV
Simple compliance
tests
May be challenging, depending on
programming and control settings
Impact on
development of more
effective business
models and
technology
capabilities
May inhibit development of more
effective
frequency
response,
spreading available response in
time
using
controlled
smart
charging.
May inhibit combining frequency
response with other nascent DSR
propositions in combined platforms,
hence lowering overall overhead
costs and increasing value to
consumer
Dynamic interaction
with other
May require collaborative actions
with DNOs to limit local network
60
Frequency Sensitive EV and Heat Pump Power Consumption
Final Report
stakeholders
impacts in some areas
8.2.2 Heat pumps
The comparative analysis summarised in Table 5 does not indicate that either a mandatory
or commercial procurement model is preferred. The choice between them will largely
depend on whether a sector will develop for this opportunity and on the needs of National
Grid.
The value at an individual asset level is limited, but higher than for EVs. However there
appear less potential advantages than for EVs (lower ramping rates, no potential for bidirectional response, less development to provide other DSR uses). The limited ability of
heat pumps to contribute to frequency response at night is more fundamental, and
mandating frequency response is not expected to limit the development of solutions for
this.
Mandatory response may be more straightforward to implement than for EVs, as
appliances can be programmed to follow frequency deviations within thermostat settings
and response characteristics constraints.
Table 5 Summary comparative analysis mandatory and commercial model for heat
pumps
Green = Very high compatibility with model
Yellow =
High compatibility with model
Heat pumps
Mandatory Commercial
System potential
System cost
effectiveness
Individual asset
incentive
High system potential
Cost
effective
incumbents
compared
to
Reasonable individual asset value
Consumer quality of
service impact
Power draw can be managed
within thermostat constraints
Variation in impact
across consumers
May depend on availability of
storage or type of heat pump
Simple compliance
tests
Compliance
tests
straightforward
Impact on
development of more
effective business
models and
technology
capabilities
may
be
No active management expected to
be developed that may increase
the potential as with EVs
May inhibit combining frequency
response with other nascent DSR
propositions in combined platforms,
61
Frequency Sensitive EV and Heat Pump Power Consumption
Final Report
hence lowering overall overhead
costs and increasing value to
consumer,
however
less
developments compared to EVs
Dynamic interaction
with other
stakeholders
May require collaborative actions
with DNOs to limit local network
impacts in some areas, but less
dynamic interaction compared to
EVs
8.3 Next steps for EV and heat pump frequency response roll
out
The development of business models and technologies requires investments from
technology developers and third parties developing technologies and customer
propositions. These investments can be de-risked by a dual approach of supporting
technology development and creating commercial markets. This section sets out possible
next steps to overcome the barriers summarised in section 8.1.
As discussed in the previous section, for EVs a commercial procurement model appears to
be the most appropriate model to develop. For heat pumps both mandating and
commercial procurement may be appropriate, and National Grid may investigate the
impact and benefit of each in parallel to further technology development.
Supporting commercial market development should focus on providing confidence that
there will be a market in the long term that is accessible and amenable to frequency
response from demand side assets, and values providers based on their effective
contribution to resolving frequency management. The next steps are set out in more detail
below.
Investigation of mandatory frequency provision should focus on the impact on consumers
and other stakeholders (especially DNOs), cost-benefit analysis (including the likelihood
that the opportunity will be developed in the absence of mandating) and implications for
National Grid operations. These may be carried out in the next few years to inform the
ENTSO-E investigation of mandatory frequency response (2020 timeline) for
thermostatically controlled appliances in Ecodesign standards and demand connection
codes.
1. Near term – strategic agenda and business case


Early development may be supported by clear statements showing that frequency
response from a large portfolio of low power (kW scale) assets is being actively
explored as part of strategic agendas for system management.
Carry out technical assessment of the system and local network impacts of large
scale or clustered EV and heat pump frequency response uptake, and potential
control strategies to mitigate these.
62
Frequency Sensitive EV and Heat Pump Power Consumption
Final Report

Demonstration projects can support technology developers and aggregators in
overcoming technical barriers and the uncertainty around real life business
models. Possible options for National Grid to consider include:



Providing clarity on service requirements (response rates, response lengths,
reliability), technical requirements (power metering, verification) and
contractual terms.
Engaging with other stakeholders to define what the response characteristics
are that may need to be controlled and which will be valued for dynamic
control capability with large scale uptake. This allows developers to take this
up in technical design.
Defining baseline methodology used to identify an asset’s contribution to
frequency response.
2. Medium term – enabling deployment



Provide commercial opportunities for early adopters through commercial bilateral contracts, with less stringent technical requirements or novel
commercial models. High transaction costs and lack of transparency in
bilateral contracts would see these phased out as uptake increases.
Collaborate with DNOs to identify impact on diversity. Develop industry rules
and processes to create transparency between aggregators, National Grid,
DNOs and suppliers on location and utilisation of frequency responsive
demand. Develop processes to mitigate or limit adverse local network impacts
(thermal overload or voltage stability issues).
Collaborate with aggregators and suppliers to identify impact on settlement
(system balance) or supplier imbalance if it is not the response aggregator.
Balancing responsibility on a connection should be clearly defined and
consistently metered. There should be no gaps or overlaps in the balancing
responsibility of different actors on a connection. Depending on the
implementation of half hourly settlement, new SSCs may need to be
developed for different types of response providers.
3. Long term – market access


Develop services which remunerate higher responsiveness that some demand
side technologies may provide (fast response capability, accurate tracking of
frequency deviations), and take into account challenges and limitations of
demand side technologies (short lead times for capacity nomination, profiled
bids).
Implement industry processes and rules providing transparency between
DNOs, TSO and aggregators on location and utilisation of frequency
response, and implement processes to mitigate adverse local network
impacts.
63
Frequency Sensitive EV and Heat Pump Power Consumption
Final Report
9 Conclusion
National Grid commissioned Element Energy to carry out this Network Innovation
Allowance (NIA) project to assess the potential for electric vehicles and heat pumps to
contribute to frequency response.
The analysis shows there is a significant technical potential for both EVs and heat pumps
to contribute to frequency response by 2030. The combined annual average potential may
reach 1200MW by 2030 in the medium uptake scenario (excluding residential heat
pumps). This corresponds to an average 82% of National Grid’s projected frequency
response requirement in 2030.
There are no fundamental technical limitations for both EVs and heat pumps to implement
frequency responsive electricity consumption. However further technical development is
required for both to realise practical frequency response capability. Most heat pumps in
particular require further design iterations to meet dynamic frequency response
requirements in a safe and reliable manner. Key development areas to enable frequency
response services are the control and communication systems, both between EVs and
charge points and between heat pumps and Energy Management Systems, as well as with
DSR management platforms.
The annual average potential of EVs and heat pumps in the 2030 medium scenario
corresponds to approximately £100 million in annual revenues, based on current tendered
prices. This value could potentially be higher if the effectiveness of fast responding
demand assets in restoring system frequency deviations is taken into account in pricing.
While the overall cost of providing frequency response may be very competitive compared
to conventional thermal plants, the potential net benefit per household may be relatively
limited. This may risk limiting the participation of EV and heat pump owners in frequency
response schemes. Deployment will need to be supported by very efficient commercial
models or mandated.
The development of business models and technologies requires investments from
technology developers and third parties developing technologies and customer
propositions. These investments can be de-risked by a dual approach supporting
technology development and creating commercial markets. Such commercial markets
could provide confidence on the long term access, value and market size for these
solutions.
The development of these opportunities may be supported in the near term by clear
statements that large fleets of kW scale assets are part of strategic agendas for system
management, and supporting demonstration projects that prove the technology and
commercial structures. This may be followed with bilateral contracts to provide frequency
response from EVs and heat pumps that are structured to accommodate their specific
characteristics and innovative capabilities. In the longer term services may be adapted
similarly to accommodate these resources and benefit from more effective frequency
response capabilities.
.
64
Frequency Sensitive EV and Heat Pump Power Consumption
Final Report
Acknowledgements
Interviews with a wide range of stakeholders were carried out for this study. We are very
grateful to all interviewees for their contribution. The organisations that participated in the
consultation are listed below.











Daikin
Ecotricity
Electricity North West
E.ON
Glen Dimplex
Global Energy Systems
IBM
Mitsubishi Electric
Nissan
Northern Powergrid
OpenEnergi










Pod Point
Renault
Scottish and Southern Energy
Power Distribution
SSE
Star Renewable Energy
Transport for London
UK Power Networks
UPS
Upside Energy
Western Power Distribution
65
Frequency Sensitive EV and Heat Pump Power Consumption
Final Report
Glossary
AC
Alternating Current
ASHP
Air Source Heat Pump
BEMS
Building Energy Management System
BEV
Battery Electric Vehicle
DCC
Demand Connection Codes
DNO
Distribution Network Operator
CCC
Committee on Climate Change
CCS
Combined Charging System
CLNR
Customer Led Network Revolution
COP
Coefficient of Performance
DC
Direct Current
DCC
Data Communications Company
DfT
Department for Transport
DSM
Demand Side Management
DSR
Demand Side Response
ENTSO-E
European Network of Transmission System Operators for Electricity
EV
Electric Vehicle
EVSE
Electric Vehicle Supply Equipment
FCDM
Frequency Control by Demand Management
FES
Future Energy Scenarios
FFR
Firm Frequency Response
GSHP
Ground Source Heat Pump
HEV
Hybrid Electric Vehicle
HH
Half Hourly
IEC
International Electrotechnical Commission
ISO
International Organisation for Standardisation
LowCVP
Low Carbon Vehicle Partnership
66
Frequency Sensitive EV and Heat Pump Power Consumption
Final Report
LCL
Low Carbon London
LCNF
Low Carbon Network Fund
MBSS
Monthly Balancing Services Summary
NHH
Non Half Hourly
OLEV
Office for Low Emission Vehicles
PC
Profile Class
PHEV
Plug-in Hybrid Electric Vehicle
RCD
Residual Current Device
RED
Renewable Energy Directive
REEV
Range Extended Electric Vehicle
RHI
Renewable Heat Incentive
SME
Small or Medium sized Enterprise
SOC
State of Charge
SOF
System Operability Framework
SSC
Standard Settlement Configuration
TSO
Transmission System Operator
UKPN
UK Power Networks
ULCV
Ultra Low Carbon Vehicle
67
Frequency Sensitive EV and Heat Pump Power Consumption
Final Report
References
Options and recommendations to meet the RED transport target, Element Energy for the
LowCVP, 2014
Pathways to high penetration of heat pumps, Frontier Economics and Element Energy for
the CCC, 2013
A Guide to Electric Vehicle Infrastructure, BEAMA
http://www.iec.ch/
https://www.zap-map.com/
https://www.gov.uk/government/statistical-data-sets/veh02-licensed-cars
Assessing the viability of EVs in daily life, The Ultra Low Carbon Vehicle Demonstrator
Programme, 2013
http://www.networkrevolution.co.uk/
Low Carbon London Report C3, Network impacts of energy efficiency at scale
Assessing Heat Pumps as Flexible Load, Hong et al., Loughborough University, 2013
Impact & opportunities for wide-scale EV deployment, Low Carbon London Report B1
Infrastructure in a low-carbon energy system to 2030: Demand Side Response, Grid
Scientific and Element Energy, 2013
Green e-Motion Deliverable 9.4 Part 1, Envisaged EU mobility models, role of involved
entities, and Cost Benefit Analysis in the context of the European Clearing House
mechanism, 2014
MBSS data and FFR post assessment tender reports 2014
PJM, Performance-based Regulation Market in PJM, July 2014
PJM, monthly average regulation prices after introduction Pay for Performance (October
2012), 2011 – 2014
The Effects of Cycling on Heat Pump Performance, EA Technology report, 2012
68