Sun City - Energy load shifting and shedding

advertisement
Case Study SA-SUN
LOAD SHEDDING AND LOAD SHIFTING IN OPTIMISING WATER AND
ENERGY EFFICIENCY
This case study considers how a holiday resort with on-site water and sanitation services identified specific
areas to shift- and shed electricity loads through demand management and a multi-phased energy
optimisation project.
Load Shedding and Load Shifting in Optimising Water and Energy Efficiency
Description of Process:
Sun City is a world renowned resort that caters for up to 6058 daily visitors and > 2 million guests each year.
Water and electricity is provided on demand and often difficult to plan within a 10% confidence span. Onsite water and sanitation infrastructure and electricity supply amount to significant portion of the total
budget. The responsible practice of the Resort offset the increased environmental impact of this business,
as part of an integrated strategy to reduce the carbon footprint, as well as the water footprint.
The energy management strategy involves the upgrading of the electrical infrastructure grid in order to
consolidate Eskom feed to the substations which equated to significant savings from the lower tariff
applied to the bulk supply. The new metering system enables the accurate monitoring of all business units
on the site, and assists to identify areas for load reduction projects. From the demand circle, the Resort
electricians shift the main power consuming processes through 2 interventions:


Load shedding: actual saving of electricity via new technology and
electrical consumption drives
Load shifting: saving via the sequencing of the high demand processes
The main water supply units that have been identified to equate to high
energy demand include: the boilers that supply hot water to the hotels,
swimming pool heaters and water pump stations. Cognisance is also taken
of the energy consumption by the wastewater treatment plant for the
mechanical surface aeration of the activated sludge processes for future
optimisation.
Potential Interventions







Adoption of an Energy Management Strategy that link water, energy and other areas of facility
management into an integrated approach
Upgrading of electricity grid and installation of consumption metering in real time, and a
management system.
Identify units with high energy consumption during maximum demand periods when high tariffs
apply.
Shifting of work periods of identified equipment to time spans when lower tariffs apply
Maintaining supply MVA against setpoint MVA, revert to load shedding when exceeding set point.
Replacement of electrical geysers with solar geysers.
Upgrade of technology for pool heating and boiler to improve performance and save energy.
Range of potential savings



3% of total load shifted from peak to off peak time, 4% of standard time shifted to off peak time –
resulting in savings of 2.34% and 1.63% on total consumption.
This saving amount to R604 000 on a >R4.14million bill per month which equate to 990 000 kWh
saving/month
Further savings were recorded through projects not directly linked to the water balance.
Case Study SA-SUN
LOAD SHEDDING AND LOAD SHIFTING IN OPTIMISING WATER AND
ENERGY EFFICIENCY
Ref
Case Study SA-SUN
Response information, description and remarks
Location:
South Africa, Sun City Resort, North West Province.
Sector:
Drinking water and electricity supply
Works Owner or Operator:
The supply system is owned and operated by Sun City, a private tourism
resort. Regulated under the SA legislation and the municipal bylaws.
Size:
1683 rooms, 6085 visitors each day/night with > 2 million guests per
year, as well as >6000 staff and contractors per month. Water supplied
estimated at 150 kL/c/day and sewage at 0.75 kl/c/day.
Energy Provider:
Power is in form of electricity, provider by the national electricity
agency, ESKOM. Sun City buys electricity at R0-29/kWh during off peak,
R0-55/kWh during standard time and R2-11/kW during peak time. The
energy tariff is made up of various levies and taxes (www.Eskom.com)
Process:
The project involves a management and technical intervention, by way
of a tripartite partnership between the energy provider, the facility
owner and National Power agency.
Component:
Water supply inefficiencies addressed as part of a bigger energy
optimisation project as part of a multi-phased project over > 3 years.
Motivation for the case
study:
The increasing electricity in addition to the increased carbon and water
footprint triggered the intervention. Monthly bill is > R4.14 million per
month. Details pertaining to wastewater treatment: i) 361 000 kWh
/month average (167,000 to R 325,016); 2013 projection 369,000 and for
2014: 373,000 kWh; unit cost R 3-90/m3 wastewater treated = equal 1.52
kWh/ML/day). This latter phase will be addressed in future projects.
Process/Plant changes:
Upgrade electricity grid, install meters and BMS management system,
replace electricity based technology with solar and mechanical energy
technologies. Apply load shedding and shifting against set targets.
Civil/Physical Changes
Changes in equipment by replacing identified electrical equipment with
solar or mechanical driven equipment. Changes mostly in management
approach and management support systems, adding intelligence and real
time monitoring equipment. Water quality complies to SANS 0241 no
changes, effluent complies to Water Affairs standards (with some
exception).
Operational Changes:
Engineering oversight and project management was done by electricians
and engineers from Sun City. Software installation and operations took
place by the services providers, as part of the electricity monitoring and
management system.
Risks and Dependencies:
The difficulty to plan for a demand driven approach with varying guest’s
numbers posed a low risk to optimal planning. Some risk was involved in
applying new technology and setting up maintenance team to ensure
optimal m&O&r for equipment. No major risk elements identified.
1
2
3
4
5
6
7
8
9
10
11
12
13
Implementation:
The project was executed by the three partners: Sun city, Eskom and the
National Energy agent. Service providers were used for equipment and
installation thereof.
Energy Efficiency gains:
This saving amount to R604 000 on a >R4.14million bill per month (low
season) which equate to 990 000 kWh saving/month.
Cost / Benefit analysis:
The project cost benefit analysis indicates a return on investment of 4 to
12 months for interventions on the water supply side of the business
(year 2011 - 2012). For interventions on solar geysers and lighting
optimisation, up to 44 months ROI is recorded.
Project review:
The Sun City project is in early days, but already efforts are recognised
and data recorded and published. Sun City’s efforts in bringing the water
and energy nexus closer through a focused strategy is acknowledge by
the Department of Water Affairs through the Green Drop Certification
process.
Confidence grade
High confidence, data focus on financial aspects with supportive data
and information regarding the energy consumption before and after
interventions. The energy savings are based on real time monitoring and
transparent tariff recording and calculations. The corresponding energy
and water footprint could receive further attention.
14
15
16
17
Sun City is a world renowned resort nestled in the hart of
the South African bushveld in the North West Province
and accommodate >2 millions guests each year, and a
staff compliment of >6000 persons. The responsible care
to energy and water footprint reduction, compounded
by the increased electricity tariffs made for a strong
business decision to upgrade the electrical
infrastructure grid via a tripartite agreement between
Eskom, National power and Sun, which included
upgrades to the substations to consolidate the Eskom
feed into one centralised substation. This resulted in
meaningful savings to the facility by the lower tariff
received on the bulk supply. In addition, a metering
project has been implemented to enable accurate
reading of all the business units’ consumptions on site
on a monthly basis and to identify various areas for load reduction projects.
Description of Process
A key motivator to project approval has been the rising cost of electricity and the impact on the facility’s
carbon footprint – which subsequently stimulated good practice through energy and water efficiency
measures. The following schematic shows the Eskom tariff charges during off-, standard- and peak
electricity consumption period, as well as the associated charges during the usage periods.
Figure: Eskom Demand Tariff charges 2012:
Colour
code
Tariff period
description
Cents/kWh
(Sept-May
2011)
Cents/kWh
(June-August
2012)
Off Peak
R 0.25/kWh
R 0.29/kWh
Standard
R 0.36/kWh
R 0.55/kWh
Peak
R 0.58/kWh
R 2.11/kWh
The project commenced with the establishment of a sophisticated metering system to monitor existing
business units and account for electricity consumption. The project included various phases, some of
which are outside the water supply balance, but part of the overall (integrated) strategy:
 Load shedding: actual saving of electricity via new technology and electrical consumption drives
 Load shifting: saving via the sequencing of the
high demand processes
An early intervention (over 4 years implemented) as
part of the overall project involved the consolidation
of the various Eskom feed supplies into one
substation. The allowed for the elimination of the
various and separate customer charges demand
charges, network charges and electrical rate charges.
The project resulted in R 200 000 saving /month.
Potential Interventions








Upgrade of electricity grid / supply system
Installation of meters to monitor consumption
Installation of metering and management system to allow for real time monitoring
Identification of equipment with high usage that operated in peak- or standard time at higher tariffs
Shifting of load to ensure equipment operate in lower tariff periods
Replacement of electricity driven geysers, boilers and water pumps with solar and mechanical energy
drivers
Design of water shedding programme to reduce the operation of the water equipment within the
maximum demand period / tariff levels and shifting the operation of high consumption equipment to
more favourable times and tariffs.
The BMS monitoring & management systems were recorded (monthly) with a max MVA value,
followed by subtraction of 1MVA from the max MVA. This set MVA point are used to monitor and
compare the incomer measurements to the set point at which time the BMS will systemically start to
switch of the processes described above in the load shedding process until the value decrease below
the monthly prescribed set point.

The DSM Phase 2 project was launched in the 1st quarter of 2012 in conjunction with Eskom and
National Power (ESCO). This project effectively changes the method to heat the water in the pools
and hotels. The use of 21 electric boilers and 3 pool water
heaters result in the heat energy generated by mechanical
energy (which is normally lost), however is now used to
heat the water instead of electric elements. The efficiency
of the performance of a heat pump compared to the
standard electric boiler system is 3 : 1. The expected
reduction in electricity usage for water heating purposes on
the Resort following a measurement and verification
exercise is in the order of 60%. A survey by the University of
Pretoria confirmed that implementation of the heat pump
project would show a saving of 8MW per annum. The
current heat pump project will be completed in phases
towards early 2013 and is expected to culminate in 27 units
being installed throughout the Resort.
Benefits derived from case study:
The most significant benefits from the project (as captured by the case study) include:

The approach to energy saving linked to the water supply and equipment on the site as an
integrated approach.

The importance of monitoring and measurement systems to support decision making and inform
project priorities for future implementation

The results can be converted into kWh savings, as well as cost benefits per business unit. Estimated
energy saving of 15.4 million kWh per annum

A saving of 11,76 million kWh per annum translate to 11,210 annual GHG emissions avoided of
13,700 metric tonnes of (equivalent) CO2.
Cost Saving



3% of total load shifted from peak to off peak time, 4% of standard time shifted to off peak time –
resulting in savings of 2.34% and 1.63% on total consumption.
This saving amount to R604 000 per month which equate to 990 000 kWh saving/month.
Further savings were recorded through projects not directly linked to the water balance.
Figure: Electricity consumption profile for i) March 2012 and ii) April 2012
In financial terms, the savings translated to the following energy, cost and ROI figures:
kWh saving /
month
Rand (ZAR) value
saving /month
ROI (months)
340 000
R 204 000
29 to 44
Electrical feed consolidation
N/A
R 200 000
5
Electrical meter network (42 installations)
N/A
N/A
N/A
Optic fibre installation
N/A
N/A
N/A
BMS upgrade
N/A
N/A
N/A
Mimic panels upgrade
N/A
N/A
N/A
VSD drives installation
N/A
N/A
N/A
Heat pumps to replace boilers(7 locations)
65 000
R 400 000
12
Load shifting on boilers, pump stations and
pool heaters
N/A
N/A
N/A
990 000
R 604 000
5 (min) to 44 (max)
Project Element
Solar geyser at 6 locations
TOTAL
Note: Solar lighting devises also implemented and savings recorded – not included as part of this case study as it
falls outside the water balance.
Acknowledgement:
Vernon Victor: Energy and maintenance optimization technician, Electrical engineering Department - Sun
City Resort.
Download
Related flashcards
Create flashcards