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Energy storage for smart grid and renewables v1

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Energy storage for smart grid and renewables v1

  1. 1. Energy Storage for Renewables and MicroGrids<br />John Pappas<br />Center for Electromechanics<br />The University of Texas at Austin<br />
  2. 2. Center Experience<br />Reconfiguration via optimization<br />100+ researchers into energy storage, smart grid, and energy technology<br />Working for seven years on “Smart Grid” for DoD<br />Storage programs in flywheels, batteries, ultracaps, compressed air, and thermal<br />Using a power objective function<br />Subject to:<br />Reconfiguration approach handles:<br /><ul><li>Fuel minimization
  3. 3. Power system protection
  4. 4. Damage mitigation</li></li></ul><li>Long history in storage and load leveling systems<br />Transit Bus <br />Flywheel Battery<br />2 kWhr, 150 kW<br />30,000 rpm<br />Locomotive Load Leveling<br /><ul><li>140kWhr, 2.5 MW
  5. 5. 15,000 rpm</li></ul>Examples of demonstrated systems<br />
  6. 6. Utility Storage Flywheel<br />Pendulum-mounted steel and reinforced flywheel<br />Very large l/d<br />Sited in ground<br />No additional containment<br />Vacuum barrier<br />Surface mounted Motor/generator, bearings, gimbal<br />Life cycle cost lower than batteries<br />Initial cost competitive with batteries<br />
  7. 7. Why CEM’s Focus on Utility Storage?<br />Storage is widely recognized as critical in future power systems<br />Storage enhances insertion of renewables<br />Storage defers need for new transmission lines<br />Storage is needed for stability<br />Storage opens new opportunities for grid optimization<br />
  8. 8. Today’s Technology<br />In today’s grid<br />Batteries<br />CAES<br />Flywheels<br />Pumped hydro<br />Thermal storage<br />All work<br />So, impediment is not solely lack of technology<br />
  9. 9. Critical Questions<br />Where to add storage to grid?<br />Sources<br />Does little for peak congestion<br />Nodes<br />Likely requires largest scale<br />Loads<br />Argument for PHEV’s<br />May be better argument for stationary systems<br />What are the real costs, who pays, who benefits?<br />“Which is best technology?” is not a critical question<br />
  10. 10. Technology Comparisons<br />Given differing maturities, direct technology comparison misleading<br />Level playing field by comparing energy lost<br />Energy lost = Energy lost putting it into storage*<br />plus<br />Energy lost while in storage<br />plus<br />Energy lost retrieving from storage*<br />* Includes opportunity loss if there is a mismatch with the power demand<br />
  11. 11. Basic Efficiency - Data Summary<br />CAES Tank<br />Battery (Lead Acid)<br />Battery (NiCad)<br />Battery<br />(Li lon)<br />Super Capacitor<br />Composite Flywheel<br />Steel Flywheel<br />0.55<br />0.85<br />0.58<br />0.90<br />0.80<br />0.90<br />0.90<br />Turn around efficiency<br />Charge time (hr)<br />Self-discharge time (day)<br />Operating Power (MW)<br />Capital cost of stored<br />Energy ($/Whr)<br />Total stored energy<br />Available (MWhr)<br />Initial Cost of power ($/W)<br />O&M , Installation, Space<br />Total initial cost ($)<br />Total initial cost ($/W)<br />4.0<br />4.0<br />4.0<br />4.0<br />4.0<br />4.0<br />4.0<br />2000<br />2000<br />33<br />2000<br />33<br />1<br />0.55<br />1<br />1<br />1<br />1<br />1<br />1<br />1<br />0.17<br />0.2<br />0.46<br />1.33<br />0.5<br />1.0<br />0.4<br />4<br />4<br />4<br />4<br />4<br />4<br />4<br />0.70<br />0.225<br />0.225<br />0.78<br />0.40<br />0.28<br />0.28<br />1,380,000<br />1,025,000<br />2,065,000<br />6,100,000<br />2,400,000<br />4,280,000<br />1,800,000<br />1.38<br />1.03<br />2.07<br />6.10<br />2.40<br />4.28<br />1.80<br />Too much uncertainty to predict ultimate best choice<br />
  12. 12. Initial Cost of Delivered Energy<br />4.00<br />CAES<br />Lead acid<br />NiCad<br />Li lon<br />Super Cap<br />Comp FW<br />Steel FW<br />3.00<br />2.00<br />Cost per Watt-hr ($/Whr)<br />1.00<br />0.50<br />0.00<br />10<br />9<br />8<br />7<br />6<br />5<br />4<br />3<br />2<br />1<br />0<br />Hours Stored<br />R&D moving flywheel cross-over to 10+ hours <br />
  13. 13. Smart Grid<br />Attributes<br />Permit active participation by consumers <br />Accommodate generation and storage options<br />Enable new products, services, and markets<br />Provide power quality<br />Operate efficiently<br />Reconfigure in response to system disturbances<br />Technology<br />Traditional power engineering<br />Computing<br />Telecommunications<br />
  14. 14. Smart Grid is Growing in Two Directions<br />Top down<br />Large scale wind farms<br />Smart meters<br />Bottom up<br />Microgrids<br />Neighborhoods<br />Industry<br />Universities<br />DoD facilities<br />Urban environments<br />
  15. 15. Microgrid Considerations<br />Understanding source efficiency vs. power demand helps assess storage applicability<br />Gas Turbine Performance<br />0.7<br />0.6<br />(P1,x1)<br />0.5<br />Specific Fuel Consumption (kg/KWHr) x<br />0.4<br />0.3<br />(P2,x2)<br />0.2<br />0<br />5<br />10<br />15<br />20<br />25<br />30<br />35<br />40<br />45<br />50<br />Power (MW)<br />
  16. 16. Load Leveling Via Storage in Microgrid<br />Load Leveling<br />Analytical study comparing external storage vs. using microgrid as storage to achieve load leveling<br />0.3<br />0.2<br />Storage becomes<br />economical<br />Store Efficiency Function<br />0.1<br />Fuel consumption Function<br />0.0<br />0<br />10<br />20<br />30<br />40<br />50<br />60<br />70<br />Duty Cycle About the Mean Operating Point<br />
  17. 17. Benefits From Point Design Analyses<br />Analyses of specific technologies in a point application is the best way to make comparisons<br />Choice among storage technologies and no explicit storage depends on temporal variations within a microgrid<br />Operating economics can be properly compared to other technological imperatives<br />Storage system response times<br />Effect on operating cost of systems other than storage<br />Cost of space used for storage and other systems<br />Technology choices are driven by very specific needs<br />
  18. 18. Summary<br />Storage critical for “Smart Grid”<br />Most agree, but assume different applications<br />Excellent storage choices exist today<br />With R&D, better choices will exist in the future<br />Evolution of “Smart Grid” is a work in progress<br />Storage can help shape the evolution<br />

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