1. 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

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

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

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

5. Fossil Fuel & Biomass

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

7. Compressed Gas

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

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

10. 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?

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

12. Other Liquid metal battery Magnetic storage Thermal storage And…

13. Flow Batteries at ACEP

14. 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

15. Pumps

16. Leaks

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

18. 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

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

20. 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…

21. 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

22. 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

23. Questions?

24. 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