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