Energy Storage Overview
Thomas Johnson
Alaska Center for Energy and Power
ACEP (907) 474 1143 www.uaf.edu/acep
Alaska Center for Energy and Power http://www.uaf.edu/acep/ (907) 474 1145
Overview
• Why?• Types of storage• ACEP flow battery experiences• Energy storage in Alaska
Why Storage and Why Now?
• Balance supply and demand• Load leveling• Load shifting• UPS – Uninterruptible Power Supply• Potential to save fuel and $$$
Types of Storage
• Potential– Elevation difference– Electrochemical– Super capacitors– Chemical– Magnetic– Mechanical
• Kinetic• Thermal
Fossil Fuel & Biomass
Hydrogen
• Yes, hydrogen can be used for energy storage
• In most applications there are better alternatives
Compressed Gas
Hydroelectric
• Reservoir storage• Energy = mgh• Pumped hydroelectric
~70% efficientNeeds the right circumstancesElevation change
Super Capacitors
• “Battery”-like characteristics• Extremely rapid charge and discharge• Virtually no degradation• High self-discharge rate• Not suitable for long term storage
Flywheels
• Kinetic energy storage• Energy=1/2 mv2
• Changed from heavy rotors to fast rotors• Turn around efficiency up to 85%• Short-term storage• Containment?
Batteries
• Electrochemical storage• Can be efficient• The technology is rapidly improving• Most types degrade
Other
• Liquid metal battery• Magnetic storage• Thermal storage• And…
Flow Batteries at ACEP
Flow Batteries at ACEP
• Vanadium redox batteries• VRB and Prudent Energy• Turn around efficiency 65%-75%• Very low degradation• High self-discharge rate• The “stack” was reliable• The VRB balance of plant was not
Pumps
Leaks
Storage in Alaska
• Installations throughout the state• Various levels of success• Or lack thereof…
• A few examples:
Usibelli Coal Mine
• Electrically-operated dragline• 6 MW draw, 2 MW regeneration, 60
second cycle time• Caused grid stability problems• 40 ton, 1000 rpm Flywheel was installed
and reduced the fluctuations from 8MW to .5 MW
• Installed in 1982 and still in use
Chena Hot Springs Batteries
• 1 MW• Battery module intended as a UPS• Lead acid chemistry• Not suitable for load leveling• Never commissioned…
Premium Power Battery
• 500 kW, 3.4 MWhr• Delivered to Kotzebue in October 2011• Zinc-Bromide chemistry• Intended to provide storage during times of
excess wind.• Never commissioned• Being returned to the manufacturer…
Wales
• Wind-diesel hybrid system• Battery and thermal storage
enabled diesel-off operation• System proved it could work• For a variety of reasons, the system
is no longer used and Wales is once again 100% diesel
Golden Valley BESS
• Largest battery in the world• Nickel-Cadmium chemistry• 27 MW• 6.25 MWh capacity• Electrical Energy equivalent to ~400
gallons of fuel • It works
Questions?
For more information on the
Alaska Center for Energy and Power,
please visit
http://www.uaf.edu/acep/Or call (907) 474-1145
Alaska Center for Energy and Power http://www.uaf.edu/acep/ (907) 474-1145