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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

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Overview Why? Types of storage ACEP flow battery experiences Energy storage in Alaska

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Why Storage and Why Now? Balance supply and demand Load leveling Load shifting UPS Uninterruptible Power Supply Potential to save fuel and $$$

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Types of Storage Potential Elevation difference Electrochemical Super capacitors Chemical Magnetic Mechanical Kinetic Thermal

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Fossil Fuel & Biomass

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Hydrogen Yes, hydrogen can be used for energy storage In most applications there are better alternatives

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Compressed Gas

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Hydroelectric Reservoir storage Energy = mgh Pumped hydroelectric ~70% efficient Needs the right circumstances Elevation change

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Super Capacitors Battery-like characteristics Extremely rapid charge and discharge Virtually no degradation High self-discharge rate Not suitable for long term storage

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Flywheels Kinetic energy storage Energy=1/2 mv 2 Changed from heavy rotors to fast rotors Turn around efficiency up to 85% Short-term storage Containment?

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Batteries Electrochemical storage Can be efficient The technology is rapidly improving Most types degrade

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Other Liquid metal battery Magnetic storage Thermal storage And

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Flow Batteries at ACEP

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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

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Pumps

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Leaks

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Storage in Alaska Installations throughout the state Various levels of success Or lack thereof A few examples:

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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

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Chena Hot Springs Batteries 1 MW Battery module intended as a UPS Lead acid chemistry Not suitable for load leveling Never commissioned

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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

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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

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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

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Questions?

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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