Cost-benefit analysis of grid energy storage Robert L. Fares Graduate Research Assistant IEA Energy Storage Technology Roadmap Stakeholder Engagement Workshop September 24, 2013
Outline The limitations of a grid with no storage Application analysis: frequency regulation Future work: distribution-level storage Robert Fares Graduate Research Assistant September 24, 2013 2
The present grid delivers energy on demand Source: Texas Electricity Alliance Robert Fares Graduate Research Assistant September 24, 2013 3
Adding energy storage could improve the grid s operation 1. Reduce overall electricity costs 2. Improve electric reliability 3. Integrate renewable energy Robert Fares Graduate Research Assistant September 24, 2013 4
It is important to consider the costs and benefits of energy storage The cost of energy storage depends on the specific technology involved The benefits of energy storage depend on the service it provides and the local energy market or utility electric tariffs Robert Fares Graduate Research Assistant September 24, 2013 5
Storage application analysis Frequency regulation Robert Fares Graduate Research Assistant September 24, 2013 6
Frequency regulation balances electric supply and demand Load Without Regulation System Load 0 6 12 18 24 Hour Robert Fares Graduate Research Assistant September 24, 2013 7
Frequency regulation balances electric supply and demand Load Without Regulation Net Load With Regulation System Load Load (GW) 0 6 12 18 24 Hour Robert Fares Graduate Research Assistant September 24, 2013 8
Valuing energy storage for frequency regulation Regulation service prices Regulation dispatch signal Optimization $ Energy storage model Robert Fares Graduate Research Assistant September 24, 2013 9
Case study: a vanadium redox flow battery (VRFB) for frequency regulation in Texas Grid data Battery model Figure from: Dunn, B., Kamath, H., & Tarascon, J. M. (2011). Electrical energy storage for the grid: A battery of choices. Science, 334(6058), 928-935. Robert Fares Graduate Research Assistant September 24, 2013 10
Case study: a vanadium redox flow battery (VRFB) for frequency regulation in Texas Grid data Battery model Zhao, P., et al. "Characteristics and Performance of 10kW Class Allvanadium Redox-flow Battery Stack." Journal of Power Sources 162.2 (2006): 1416-1420. Robert Fares Graduate Research Assistant September 24, 2013 11
30 25 20 15 10 5 0 URS Capacity Price VRFB Regulation Power Dispatched 1.0 (MW) ($/MW) Our model reveals the potential value of a VRFB on a given day 0.5 0.0-0.5-1.0 1 24 0 5 10 15 VRFB Cell Current Density DynamicState$Time 20 24 0 5 10 15 VRFB Cell Voltage DynamicState$Time 20 24 0 5 10 15 VRFB State of Charge DynamicState$Time 20 24 0 5 20 24 14 12 10 8 6 4 2 0 60 (ma/cm2) ($/MW) DRS Capacity Price -60 1 24 Wholesale Energy Price 40 1.50 30 1.45 (V) ($/MWh) 50 20 1.40 1.35 10 1.30 0 1 24 VRFB Dispatch Signal 1.0 0.5 0.0-0.5-1.0 (%) +1 URS -1 DRS 0 0 5 10 15 20 24 80 70 60 50 40 30 20 10 15 Hour Hour Robert Fares Graduate Research Assistant September 24, 2013 12
We use three years of ERCOT data to estimate the value of a VRFB Daily Regulation Service Revenue ($) 4500 3000 1500 0 January 2007 July 2007 January 2008 July 2008 January 2009 July 2009 December 2009 Robert Fares Graduate Research Assistant September 24, 2013 13
We use three years of ERCOT data to estimate the value of a VRFB Net Present Value ($/kw) 1000 Discharge Duration 30 minutes 1 hour 500 2 hours 3 hours 4 hours 0-500 -1000-1500 System Cost 1 hour: $1460-1613/kW 4 hours: $1919-3279/kW 500 1000 1500 2000 2500 3000 3500 VRFB System Cost ($/kw) Robert Fares Graduate Research Assistant September 24, 2013 14
Conclusions A VRFB operating as a generator to provide frequency regulation is just barely cost competitive To be an appealing technology, grid storage will most likely have to provide transmission and distribution services in addition to electricity market transactions Robert Fares Graduate Research Assistant September 24, 2013 15
For more details on our analysis Fares, R. L., Meyers, J. P., & Webber, M. E. (2014). A dynamic model-based estimate of the value of a vanadium redox flow battery for frequency regulation in Texas. Applied Energy, 113, 189-198. doi: 10.1016/j.apenergy.2013.07.025 Robert Fares Graduate Research Assistant September 24, 2013 16
Future Work Cost-benefit analysis of distribution-level energy storage Robert Fares Graduate Research Assistant September 24, 2013 17
Where energy storage is located affects its benefit Source: Texas Electricity Alliance Robert Fares Graduate Research Assistant September 24, 2013 18
Real-life electricity data will be used to evaluate distribution-level storage Electricity data are being collected from over 300 residences 185 homes in the study are equipped with rooftop photovoltaic panels Electricity use and solar production are recorded every one minute Robert Fares Graduate Research Assistant September 24, 2013 19
Microgrid and Virtual Power Plant Robert Fares Graduate Research Assistant September 24, 2013 20
Microgrid and Virtual Power Plant Robert Fares Graduate Research Assistant September 24, 2013 21
Acknowledgements The University of Texas at Austin Dr. Michael E. Webber Pecan Street Inc. U.S. Department of Energy Smart Grid Demonstration Program Robert Fares Graduate Research Assistant September 24, 2013 22
Robert L. Fares Graduate Research Assistant robertfares@utexas.edu www.webberenergygroup.com/people/robert-fares