Potential benefits of energy storage using Texas as case study - 5256

The evolution of the electricity generation mix to include non-dispatchable renewable energies is leading energy vendors to consider energy storage as a way to stabilize and maximize revenue. Thermal storage devices, such as molten salt, pumped heat electricity storage (PHES), or steam accumulators, allow the energy producer to store energy while electricity prices are low and discharge when high, provide reserve capacity, and contribute to ancillary markets. In order to assess the increase in revenue that an energy producer could attain, Texas RTM (Real Time Market) and DAM (Day Ahead Market) data was analyzed for different regions of Texas and at different times of the year. Data was analyzed one month at a time with the assumption that storage was instantly available for energy discharge and that it could not charge at the same time it was discharging. Texas incorporates many different energy generators, but above all: nuclear reactors and variable renewable energies. Storage efficiencies ranging from 70-95% were tested. The discharge rate of the stored energy was varied from its reference value of equality to its maximum charge rate. Higher discharge rates were found to offer increased revenue benefits, although price feedbacks associated with high discharge rates were not considered. Costs resulting from fewer plant start-ups and benefits of storage for alleviating congestion or providing ramping regulation were not considered in this initial work. The revenue enhancement from energy storage, especially in areas with high variable renewable energy (VRE) contribution (such as West Texas), can approach 30% and averages around 15% at 90 % efficiency. A 15% increase of revenue corresponded to 150 hours per month of active storage (or a quarter of the hours available in a month) is a more realistic estimate of the increase in revenue feasible by the energy producers if employing energy storage devices. (authors)