Electrical Energy Storage Options
Outline of Presentation
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Why Do We Want Storage?
Ontario Electricity Demand
The Cost of Dispatching/Curtailing Generators (Load Following)
Benefits of Storage
Storage Options
The Challenges for Storage
How Much Storage Do We Need?
How Much Does Storage Cost?
Alternatives to Storage
Summary and 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). Detailed analysis was
done in 2011 but load data from 2010 to 2013 was similar. 2014 was an
unusually cool summer and the highest peak load occurred in the winter.
 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 2013 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=pres_lib#peo
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Electrical Energy Storage Options
Why Do We Want Storage ?
 Customer load varies significantly over time. 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, can
change output very quickly opposite to demand and can disappear for
extended periods of time across the entire province.
 Storage is an integrating technology – enables supply to better match
demand.
 Ontario has some hydroelectric storage but not enough to handle
nearly 10,000 MW of planned intermittent renewable generation.
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Electrical Energy Storage Options
Ontario Electricity Demand – Daily Min/Max in 2011
Highest Daily Load
Lowest Daily Load
Minimum load is 10,800 MW.
Maximum load is 25,450 MW.
Grid overall capacity factor is 63%.
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Electrical Energy Storage Options
Ontario Electricity Demand - Daily Variations
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Electrical Energy Storage Options
Ontario Electricity Demand – Weekly Variations
Wind Generation High Demand Week
Solar Generation High Demand Week
Note: The gap between the 2 lines can be filled in by backup generation or by stored energy.
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Electrical Energy Storage Options
The Cost of Dispatching/Curtailing Generators (Load Following)
Abbreviations:
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Note: Data is for existing plants. Wind and solar are shown using Ontario FIT 2013 rates
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 on the load side of the lines.
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Electrical Energy Storage Options
Benefits of Storage
Note: Storage can reduce the peak load on transmission
and distribution lines if it is installed on the load side.
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Electrical Energy Storage Options
Storage Options
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Traditional Storage options:
 Short term (daily) storage:
 Batteries,
 Flywheels,
 Compressed air (tanks & underwater volumes).
 Dam and pumped hydroelectric with small reservoirs – eg:
Niagara Pumped Generating Station.
 Longer term (seasonal) 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
Battery Storage – A123 Lithium Ion (utility size)
( 2 MW/4 MWh )
http://www.a123systems.com/grid-storage-technology.htm
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Electrical Energy Storage Options
Flywheel Storage – Temporal Power (50 kWh)
http://temporalpower.com/wp-content/uploads/2014/06/
Features-and-Benefits-of-the-Temporal-Flywheel-Energy-Storage-System1.pdf
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Electrical Energy Storage Options
Compressed Air Energy Storage – MacIntosh Plant (USA) – 110 MW
http://www.powersouth.com/mcintosh_power_plant
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Electrical Energy Storage Options
Pumped Hydroelectric Storage – Niagara PGS
147 MW at NPGS, approx 1,200 MW p-p swing at Beck GS site
http://www.opg.com/power/hydro/niagara_plant_group/adambeckpgs.asp
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Electrical Energy Storage Options
Storage Options
 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
Power to Gas Storage
E-ON Falkenhagen Facility (2 MW, 360 m3/hr H2)
http://www.fuelcelltoday.com/news-events/news-archive/2013/june/firsthydrogen-from-eon-power-to-gas-plant-injected-into-the-natural-gas-grid
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Electrical Energy Storage Options
The Challenges for Storage
 Large electrical demand variation increases the required peak power rating
in kW and the energy 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 (10 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.
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Electrical Energy Storage Options
How Much Storage Do We Need
 To handle 7,500 MW of wind on a seasonal basis (no waste at any time)
would require about 500 hours of storage. A 750 sq. km. upper reservoir
(about the size of Lake Simcoe), that is 15 m deep and 100 m above the
lower reservoir or lake would be needed.
 A more practical and less costly approach is to use storage to shift each
day’s peak load to fill in the night time dip so each day’s load would be
essentially flat. A flat load profile each day has a net present value of
about $20 Billion over a 30 year period at a 5% discount rate.
 Only about 5,700 MW of storage for 7.5 hours would be needed to flatten
the daily load profile.
 The cheapest seasonal storage option is pumped hydroelectric but that
would cost over $40 billion dollars. Still to expensive to be practical.
 Battery storage would be about 5 to 10x more expensive.
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Electrical Energy Storage Options
How Much Storage Do We Need?
Constant load each day
Minimum load rises from 10,800 MW to 12,770 MW)
Maximum load drops from 25,450 MW to 22,300 MW.
Capacity factor rises from 63% to over 72%.
Requires 5,700 MW and 43,000 MWh of storage (7.5 hours).
Present value is > 20 $B but cost is > 40 $B for pumped hydro.
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Electrical Energy Storage Options
How Much Does Storage Cost?
 Electric storage is expensive – see 2010 EPRI Report 1020676.
 Storage must meet both the power delivery and energy storage rating requirements.
Technology
k$/kW
(power)
k$/kWh
(energy)
Comment
Batteries
1-5
0.2 - 5.0
Flywheels
2
2-9
Compressed gas
1–2
0.1 – 0.5
Low efficiency
Pumped hydro
1–9
0.2 – 0.9
Depends on geography
Power to Gas
Not avail.
Not avail.
Still in development
Short life 3 – 15 yrs
10 hours max storage time
Note: Batteries used for voltage regulation (less than 1 hour storage) on the
distribution system is now cost effective compared to alternative equipment.
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Electrical Energy Storage Options
Alternatives to Storage
No energy is
wasted with
these options.
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Energy is wasted
with these
options.
 Curtailment of excess Hydroelectric (spill)
 Curtailment of excess solar and wind generation
 Curtailment of excess nuclear using steam bypass
Demand management including load shifting
Load following at existing gas-fired plants
Steam diversion to district heating system
Hydrogen production during off-peak hours
Energy exports (often below the total cost of
production)
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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 at lower cost to
maintain supply-demand in balance until storage costs drop.
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Electrical Energy Storage Options
Questions ?
Notes:
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http://www.ospe.on.ca/?page=pres_lib#peo
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