Electrical Energy Storage Options
Joint OSPE – PEO Chapter
Energy Policy Presentation
Prepared by OSPE’s Energy Task Force
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Electrical Energy Storage Options
Outline of Presentation
 Why Do We Want Storage?
 Ontario Electricity Demand
 The Cost of Dispatching Generators (Load Following)
 Benefits of Storage
 Storage Options
 The Challenges for Storage
 Alternatives Without Storage
 Q&A period.
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Electrical Energy Storage Options
Data Sources for Today’s Presentation
 The Ontario generation (except for solar) and customer demand
data was obtained from the IESO website (http://www.ieso.ca).
 Solar flux data comes from the Canadian Weather for Energy
Calculations (CWEC) dataset for Toronto, Environment Canada. Solar
generation output simulations were produced courtesy of CarbonFree
Technology using PVsyst simulation software.
 Electricity production cost data was obtained from Ontario FIT rates
and the Projected Costs of Generating Electricity, 2010 Edition,
Organization for Economic Co-operation and Development, median
case with carbon tax removed.
 You can download OSPE energy policy documents and this slide
presentation at:
http://www.ospe.on.ca/?page=adv_issue_energy
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Electrical Energy Storage Options
Why Do We Want Storage ?
 Customer load varies significantly over time (very low in the
spring at night and very high in the summer during the day). The
summer peak is almost 250% higher than the spring low.
 Some generation technologies cannot adjust output to match
demand (limited ramp rates, minimum loads, etc.).
 Some generation technologies (wind and solar) are intermittent
and can change output very quickly opposite to demand and can
disappear for extended periods of time across the province.
 Storage is an integrating technology – enables supply to better
match demand.
 Ontario has some hydroelectric storage but not enough to
handle 10,000 MW of planned intermittent renewable generation.
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Electrical Energy Storage Options
Ontario Electricity Demand – Daily Min/Max in 2011
2011 Average annual grid capacity factor was 63%
2011 Minimum demand was 42% of peak demand
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Electrical Energy Storage Options
Ontario Electricity Demand - Daily Variations
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Electrical Energy Storage Options
The Cost of Dispatching Generators (Load Following)
Abbreviations:





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LCOE = the levelized
cost of electricity =
total lifetime costs
divided by energy
produced.
DF = discount factor
CCGT = Combined
Cycle Gas Turbine
M.BTU = Million
British Thermal Units
CF = Capacity Factor
Electrical Energy Storage Options
Benefits of Storage
 Storage provides renewables with a zero GHG emission backup.
 Storage can support voltage regulation and grid frequency
regulation.
 Storage reduces the amount of dispatching (load following)
imposed on generators (improves plant capacity factors)
 Storage reduces the natural gas plant capacity needed to meet
peak demand and reserves.
 Storage enables better utilization of base-load nuclear plants.
 Storage can reduce the required capacity of transmission and
distribution lines if it is located optimally.
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Electrical Energy Storage Options
Benefits of Storage (continued)
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Electrical Energy Storage Options
Storage Options
 Traditional Storage options:
 Short term storage:
 Batteries,
 Flywheels,
 Compressed air (tanks & underwater volumes).
 Dam and pumped hydroelectric (with small reservoirs – eg
Niagara Pumped Generating Station).
 Longer term storage:
 Compressed air in underground caverns,
 Dam and pumped hydroelectric (with very large reservoirs –
eg: Quebec’s James Bay development).
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Electrical Energy Storage Options
Storage Options (continued)
Non-traditional Storage options:
 Electricity  Stored Hydrogen  Combustion  Electricity
 engine or fuel cell combustion
 low round trip efficiency
 better suited to off-grid applications that displace diesel
 Electricity  Hydrogen  Injected into Gas Network  Electricity
 known as power-to-gas or P2G
 low round trip efficiency
 limits to the amount of hydrogen in natural gas lines
 ample seasonal storage capability
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Electrical Energy Storage Options
The Challenges for Storage
 Large electrical demand variation increases the required peak power
rating of storage in kW and the integrated capacity rating in kWh.
 Seasonal storage (shifting production from spring to summer and
autumn to winter) is the most valuable but it is also the most
expensive and environmentally disruptive.
 All storage options lose some of the stored energy over time (5 to
50% depending on technology and storage duration).
 Hydroelectric storage Is the cheapest large scale storage but you
need ideal geography – not available in Ontario. A 5,000 MW storage
capability to handle 7,500 MW of wind requires 750 sq km upper
reservoir (about the size of Lake Simcoe), 15 m deep and 100 m above
the lower reservoir or lake.
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Electrical Energy Storage Options
The Challenges for Storage (continued)
 Cost is prohibitive – see 2010 EPRI Report 1020675
 Batteries: 1 to 5 k$/kW & 0.2 to 5.0 k$/kWh (short life, 3 to 12 yrs)
 Flywheels: 2 k$/kW & 2 to 9 k$/kWh (10 hrs max storage)
 Compressed Gas: 1 to 2 k$/kW & 0.1 to 0.5 k$/kWh (low efficency)
 Pumped Hydroelectric: 1 to 9 k$/kW & 0.2 to 0.9 k$/kWh (uses large
land areas)
 Power-to-Gas: commercial costs not yet available
 Batteries to provide voltage regulation for short storage periods (less
than 1 hour) on the distribution system is now cost effective.
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Electrical Energy Storage Options
Alternatives Without Storage
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Improved demand management & load shifting
Improved load following at existing plants
Surplus steam to district industrial process steam system
Produce hydrogen during off-peak hours
Export energy at below the cost of production.
 Hydroelectric spill
 Dispatch Solar and wind generation down
 Improve nuclear steam bypass capability
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No
energy is
wasted
with
these
options.
Energy is
wasted
with
these
options.
Electrical Energy Storage Options
Summary
 Storage is an elegant solution.
 Much too expensive now to deploy on a large scale.
 Other non-storage options are available to manage
supply-demand balance until storage costs drop.
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Electrical Energy Storage Options
Questions ?
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