POWER-TO-GAS – ENERGY STORAGE: CLEAN FUEL
SUPPLEMENT
Figure 1 – Power-to-Gas Energy Storage: Elements of Value
Energy storage: Clean fuel
n a world in which fossil fuel energy is becoming ever more
scarce and expensive and countries are struggling to meet their
carbon reduction obligations, hydrogen solutions have finally
reached the top of energy agendas. ITM Power manufactures
integrated hydrogen energy solutions that are rapid response and
high pressure that meet the requirements for grid balancing and
energy storage services, and for the production of clean fuel for
transport, renewable heat and chemicals. The international demand
for these solutions is increasing.
• Grid balancing and rapid response demand-side services are
crucial for the integration of high proportions of renewable
energy supply on the electricity grid
Energy storage: Power-to-Gas
Power-to-Gas (P2G) energy storage is the process of converting
surplus renewable electricity into hydrogen by rapid response
electrolysis and its subsequent injection into the gas distribution
network. With more and more renewables being added to the mix,
the need for grid balancing and energy storage increases.
The existing infrastructure can be utilised by linking existing
power and natural gas networks. This infrastructure can be
recharged without having to wait for it to discharge first, using rapid
response electrolysers to convert electrons to hydrogen; critical for
storing excess renewable energy whenever it is generated. This
allows for the storage of significant amounts of energy and the
provision of CO2 neutral fuels in the form of the resulting renewable
energy gas mix of hydrogen and methane.
Electrolysis has a multi-faceted value-in-use when applied to
the P2G approach, through being a controllable load, electrolysis
can perform grid balancing and so reduce dependency on reserve
• Energy storage provision has started to become a mandatory
requirement in areas of the world such as California; it is
recognised as an essential pre-requisite for renewable energy
deployment
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Value to the
Gas Grid
Value to the
UK Economy
•
•
•
•
•
•
• Decarbonising gas in line
with legislation
• Providing renewable heat
• Reducing GHG emissions
from gas transportation
• Reducing fuel imports
• Improved energy security
• Aiding meeting international
green obligations
• Creating jobs in manufacturing
Avoided wind curtailment
Avoided infrastructure upgrades
Allowing additional RE onto grid
Reduced reserve power
Reduce CO2 from GTs
Absorbing reactive power
power plants. It can serve to reduce the curtailment of wind and
solar power sources (creating value out of electricity that would
otherwise be wasted by ‘valley filling’ electrical load profiles). It can
reduce capital expenditure on upgrading electricity infrastructure by
absorbing power locally that cannot otherwise be transferred away.
The hydrogen produced can be sold to the gas system to displace
natural gas, so reducing greenhouse gas emissions and reliance
upon fuel imports. If the power is derived mainly from renewable
power sources, only low-carbon hydrogen will be produced.
Thereby the P2G approach can facilitate a transition from natural
gas to a ‘green’ mixed gas by making use of both of the UK’s existing
energy grids (see Figure 1, above).
Power-to-Gas
I
Value to the
Power Grid
• Energy security and fuel security has risen to the top of the
geopolitical agenda
• Price volatility of fossil fuels is driving an industrial substitution
to more
Growing wind generation
Rather than turn down the wind power, an alternative option is to
turn ‘on’ a load, this is called demand side management. ITM Power’s
particular demand side load is a rapid response electrolyser. It is
turned ‘on’ when balancing against renewable power and generates
a clean useful fuel, renewable hydrogen gas, which can be put
directly into the gas grid.
National Grid spent £700m on grid balancing services in the period
2010-2011, rising to £1.1bn in 2012-2013. By 2020 estimates across
the industry vary from £2bn to as much as £6bn for grid balancing
services. What is needed is more and more rapid response demand
side loads; as the amount of inertia in the network is reduced, the
demand side management requirement increases.
The UK’s 2020 target for total wind capacity is over 30GW, if only
4% of that wind is curtailed by then, it is still 2.8 terawatt hours of
energy, which is a lot of electrolysis, but only half of 1% of hydrogen
mixed in the gas grid.
This highlights how large the gas grid is and what a practical store
it is for renewable energy. In the US the California Public Utilities
Commission unanimously approved its proposed mandate that
will require the state’s big three investor-owned utilities to add 1.3
gigawatts of energy storage to their grids by 2020.
Technology options
Energy storage in general is segmented by discharge time and
energy storage size. For extremely short bursts of energy (less than
a cycle) for power quality work, a flywheel is the preferred option.
“At the end of 2013, the plant
injected hydrogen for the first
time into the Frankfurt gas
distribution network”
For hours of energy storage a battery would be used, but the issue
with batteries is all of the energy is stored inside the battery – so
if the storage needed was greater than the capacity of the battery,
another battery would be required (see Figure 2, page 22).
With hydrogen, the energy rating and the power rating are
separate. So an electrolyser can run for as long as the renewable
power lasts, be that seconds, or hours. Power-to-Gas energy storage
considers a larger timescale of gigawatt, terawatt hours and annual
or seasonal energy storage, rather than hours of energy storage.
How much hydrogen can you put into the gas grid?
The Dutton limit highlights gas interchangeability and was used
when the UK changed from town gas to natural gas in the early
1970s, when the gas system had 60% hydrogen in it. Today that limit
is around 12% and Holland has adopted the Dutton limit, Germany
is at 10%, most of Europe is clustered around 5%, and ITM Power
has recommended that the 0.1% limit in the UK is increased to 3%.
The UK imports half of all its gas, we then re-export 10% and some
of it goes to power generation, but the bulk of it goes towards heat.
If the hydrogen made from renewable power was to be injected into
the gas grid, this would provide renewable heat on a large scale.
Case Study – Thüga Group plant in Frankfurt
Given the high volumes of energy that must be stored, powerto-gas technology holds great significance. According to Thüga’s
analysis, energy storage requirements in Germany could be as
high as 17 terawatt hours (TWh) by 2020, and reach 50 TWh by
2050. The municipal gas distribution network can easily absorb
these quantities.
Thirteen companies of the Thüga group have combined their
know-how and capital in a project platform to jointly invest in the
development of P2G storage technology and now operate an ITM
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POWER-TO-GAS – ENERGY STORAGE: CLEAN FUEL
SUPPLEMENT
Figure 2 – Energy Storage Technologies
its three-year operational phase, during
which time the plant will participate
in the balancing energy market and
provide negative balancing power. That
Power-to-Gas
means, when too much power is on
1 Year
Synthetic Natural Gas
1000
the electrical grid, at the request of the
1 Month
transmission system operator (TSO), the
Pumped
100
Storage
load of the electrolyser will be increased.
Compressed
1 Day
In this case, the plant absorbs the excess
10
Air Storage
Power-to-Gas
power and converts it into hydrogen.
Hydrogen
1
This also contributes to the stability of
Hour
Batteries
the electricity grid.
0.1
At the end of 2013, the plant injected
00.1 Flywheel
hydrogen for the first time into the
Frankfurt gas distribution network,
0.001
becoming the first plant to have ever
1 kWh 10 kWh 100 kWh 1 MWh 10 MWh 100 MWh 1 GWh 10 GWh 100 GWh 1 TWh 10 TWh 100 TWh
injected electrolytic generated hydrogen
Storage
into the German gas distribution
network. Final acceptance of the plant
Power HGas plant in Frankfurt, Germany. The project is supported was achieved at the end of March 2014, which reflected the timely
by the Hessian Ministry for the Environment, Energy, Agriculture achievement of all milestones set.
and Consumer Protection.
The focus is on testing the practicality of P2G technology. The Clean fuel
companies are confident that in the long-term this technology The world’s dependence on fossil fuels for transportation is hugely
has the greatest potential to store excess amounts of renewable costly and unsustainable, with demand only set to increase as
energy, as the development of storage technologies is one of the countries develop and populations increase. Hydrogen Fuel Cell
main challenges for the energy transition (Energiewende), if the Electric Vehicles (FCEVs) offer the ability to meet policy objectives
integration of wind and solar power is to succeed. ITM Power’s of air quality and low carbon transport. This enables the public and
proton exchange membrane (PEM) electrolyser is the core of the business organisations to travel and transport goods with clean
system in Frankfurt am Main.
emissions, without disruption to routine, a key requirement for the
The plant converts electrical energy into chemical energy and rate of adoption and acceptability of ultra-low emission vehicles.
thus facilitates the storage of electrical energy. The gas mixing
Auto OEMs are rolling out FCEVs that require a high purity
plant ensures that the mixture of hydrogen in the gas distribution hydrogen fuel. Hyundai has commenced production, with Toyota
network does not exceed 2% by volume. The plant is now entering to follow suit later in 2014 and then Honda and others from 2015.
Hydrogen fuel cell cars are now being sold and global hydrogen
Thüga Group’s Power-to-Gas plant
refuelling station infrastructure programmes are underway. Air
in Frankfurt am Main, Germany.
quality regulations are also stimulating the need for hydrogen as a
clean fuel for clean transport emissions, in city regions around the
world. ITM Power is part of the UK, Swiss, US and French hydrogen
mobility programmes and is currently building five refuelling
stations for the UK; two for the Isle of Wight for the Island Hydrogen
project and three for London, for the HyFive project. The UK
H2Mobility programme is looking to roll-out 65 stations over the
next few years.
HyFive is a pioneering £31m project involving leading motor
manufacturers, hydrogen fuel suppliers, the Mayor of London’s
Office, and energy consultancies to make hydrogen vehicles a viable
and environmentally friendly choice for motorists across Europe.
Five different manufacturers have agreed to deploy a total of 110
hydrogen fuel cell vehicles at several European locations (Bolzano,
Copenhagen, Innsbruck, London, Munich, Stuttgart) and develop
new clusters of hydrogen refuelling stations.
ITM Power was selected by the London Hydrogen Partnership to
Discharge Time (H)
Various energy storage technologies all have
different durations and power capabilities, as shown below.
22
Clockwise from left: Stephen Jones, Managing Director of ITM Power Inc., examines the hydrogen refuelling station bound for Hyundai in California;
Close-up of a gas mixing plant; Power self-pressurising PEM electrolyser stacks from ITM Power.
be the hydrogen refuelling station partner for London. This resulted
in an award of contract to supply three ITM Power electrolyserbased refuelling stations. The Mayor of London’s Office announced
the award, which is funded by the European Union Fuel Cells and
Hydrogen Joint Undertaking.
The contract is worth approximately £2.8m to ITM Power and
results in three 80kg/day hydrogen stations being deployed in
London. These three new stations will form part of three European
regions deploying six new 700 bar hydrogen refuelling stations and
incorporate 12 existing stations in the project. The fuelling station
networks will offer hydrogen as a genuine fuelling choice for endusers. Working with other partners in the project, Air Products, Linde,
OMV and the Copenhagen Hydrogen Network, will stimulate the
network density required for full commercial roll-out of hydrogen
refuelling and FCEVs across Europe. The hydrogen stations are due
to be operational in 2015, by which time the vehicle manufacturers
in the partnership will have started to put hydrogen fuelled cars on
sale in some European markets.
The ‘Island Hydrogen’ project on the Isle of Wight will see the
deployment of an 80kg/day hydrogen refuelling station to refuel
FCEVs which will be located in East Cowes, and a 15kg/day marine
refuelling station, at Ventnor Marina for Cheetah Marine. These two
stations are scheduled to be operational by fourth quarter 2014.
ITM Power has seen a big pull from the US since the formation
of ITM Power Inc. and is a founder member of the US Government
hydrogen mobility initiatives H2USA and H2First – leading to
success in receiving two orders for hydrogen refuelling stations
in the US. Both awards to date have come out of the pioneering
California Energy Commission solicitation process where $200m is
being made available for hydrogen fuelling infrastructure through
an annual competitive tendering process.
“ITM Power has seen a big
pull from the US since the
formation of ITM Power Inc.
and is a founder member of the
initiatives H2USA and H2First”
The first is an order from Hydrogen Frontier Inc. to supply Hyundai’s
headquarters in Chino, California with a high pressure electrolyserbased hydrogen fuelling station. This station will be 100kg/day and
be 100% renewable. It is set to be operational in fourth quarter 2014.
The second was a Notice of Proposed Award from the California
Energy Commission to supply a public 100kg per day turnkey
hydrogen refuelling station in Riverside, California. The refuelling
unit will replace a smaller, outdated station and will be capable of
generating 100kg/day of hydrogen with the ability to dispense at
both 350 and 700 bar. The station will be operational by October
2015. gw
All pictures courtesy of ITM Power
ABOUT THE AUTHOR
Founded in 2000, ITM Power manufactures integrated hydrogen
energy solutions that are rapid response and high pressure that
meet the requirements for grid balancing and energy storage
services, and for the production of clean fuel for transport,
renewable heat and chemicals.
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