Compressed Air, Flywheels and Batteries

1. Compressed Air, Flywheels and Batteries Nabil Reza

2. Compressed Air Energy Storage • Off-peak electricity is used to power a motor/generator that drives compressors to force air into an underground storage reservoir. • When the demand for electric power peaks, The compressed air is returned to the surface, and is fed into a gas turbine, allowing the turbine to produce electricity more efficiently. • Natural Gas is burned to preheat air. • Storage reservoirs can be large underground caverns, depleted wells, or aquifers.

3. Structure

4. CO2 Reductions • CAES power plant system can achieve >85% reductions in fossil fuel use. • Can achieve over 80% reduction in CO2 output • Adiabatic Compressed-Air Energy Storage recovers the heat that emerges during air compression. • The stored thermal energy replaces the need for natural gas, causing the entire system to run on renewable power alone

5. Adiabatic CAES http://www.youtube.com/watch?v=K4yJx5yTzO4

6. Implementation

7. Current Installations • 280 MW plant in Hunthorf, Germany - been active since 1978 • 110 MW plant at McIntosh, Alabama - operating since 1991

8. Cost & Efficiency • Insatallation cost - Depending on hours of storage, $750/kW to $1,200/kW. • Running cost at about 10.5 cents/kWh • Diabatic storage efficiency is around 55% • 70% for adiabatic CAES

9. Advantages • CAES systems can be used on very large scales. CAES is ready to be used with entire power plants. • Fast start-up time – 9 min, compared to 20 min for conventional combustion turbine • Helps solving peak load crisis

10. Flywheel • A flywheel is a flat disk or cylinder that spins at very high speeds, storing kinetic energy. • When required, the flywheel then delivers rotational energy to power an electric generator until friction dissipates it.

11. Structure http://www.youtube.com/watch?v=eCtlfj4kMJs

12. Kinetic Energy • Ef = (1/2) x I x ω2 where Ef = flywheel kinetic energy (Nm (Joule), ftlb) I = moment of inertia (kg m2, lb ft2) ω = angular velocity (rad/s) • I = k x m x r2 where k = inertial constant m = mass of flywheel (kg, lb) r = radius (m, ft) 

13. Physical Characteristics • Tensile strength - the stronger the disc, the faster it may be spun, and the more energy the system can store. • Energy storage efficiency - 50% for mechanical bearings, 85% for magnetic bearings

14. Current Installations & Costs • Beacon Power - 20 MW plant in Pennsylvania • Installation cost - around $1,500 per kilowatt

15. Advantages • Little affected by temperature fluctuations, • Take up relatively little space • Have lower maintenance requirements than batteries • Very durable.

16. Batteries • Storage devices that convert Chemical Energy to Electrical Energy • Batteries are made up of cells, containing a chemical called an electrolyte. • Each cell has two electrically conductive electrodes immersed into its electrolyte, one releases electrons into the electrolyte, and the other absorbs them. • When an electrical device is connected to the electrodes, an electrical current flows through it and provides electric power for its operation.

17. Battery Types • Lead-Acid • Lithium-ion • Lithium polymer • Nickel metal hydride • Sodium sulfur • Flow Battery

18. Flow Battery • Electrolyte is stored in external containers and circulated through the battery cell stack as required. • Flow batteries use two liquid electrolytes that react when pumped through a cell stack. The battery is broken down into a cell stack and two large electrolyte tanks. • As the electrolyte flows past a porous membrane in each cell, ions and electrons flow back and forth, charging or discharging the battery.

19. Structure http://www.youtube.com/watch?v=0Uk0GQNgtqg

20. Sodium Sulphur Battery • The active materials in a NaS battery are molten sulfur as the positive electrode and molten sodium as the negative. • The electrodes are separated by a solid ceramic, sodium - alumina, which also serves as the electrolyte. • During Charge and Discharge cycle, electrons flow from Na to S and vice versa through an external circuit.

21. Structure

22. Current Installations • Flow Batteries • 250 KW installation in Castle Valley, Utah • NaS Batteries • 4 MW installation for Texas Power Grid • 270 MW installation in Japan by Tokyo-based NGK Insulators

23. Cost & Efficiency

24. Conclusion • Electricity storage can be deployed throughout an electric power system—functioning as generation, transmission, distribution, or end-use assets. • Sometimes placing the right storage technology at a key location can alleviate a supply shortage situation, relieve congestion, defer transmission additions or substation upgrades, or postpone the need for new capacity.

25. References • http://www.rwe.com/web/cms/en/183732/rwe/innovation/projects-technologies/energy-storage/compressed-air-energy-storage/ • http://thinkprogress.org/climate/2009/08/31/204578/clean-energy-storage-wind-solar/?mobile=nc • http://www.pangeaexploration.com/compressed_air_energy_storage.htm • http://www.dg.history.vt.edu/ch2/storage.html • http://www.ngpowereu.com/article/flywheel-power-and-energy-storage/ • http://www.greentechmedia.com/articles/read/beacon-powers-bankruptcy-autopsy • http://spectrum.ieee.org/energy/the-smarter-grid/batteries-that-go-with-the-flow • http://www.electricitystorage.org/technology/storage_technologies/batteries/soidum_sulfur_batteries/ • http://www.eia.gov/todayinenergy/detail.cfm?id=6910#tabs_ElecStorage-1 • http://www.nrel.gov/learning/eds_batteries.html • http://www.nrel.gov/learning/eds_compressed_air.html • http://www.nrel.gov/learning/eds_flywheels.html

26. THANK YOU