The role of energy storage in firming up PV power production for utilities

The increased penetration of renewable energy sources like wind and solar in the utility grid is likely to cause grid instability in the near future. Today, instabilities in the grid are averted by excess generation capacity and transmission between over- and under-production regions. In some cases now, and in most cases in the very near future, local instabilities can develop from wind and/or solar energy generation that will not be mitigated by transmission capacity and the only recourse will be excess generation or energy storage. This presentation discusses the value of energy storage in backing up the grid alone and in backing up the grid and solar energy generation.

The presentation investigates the conditions for using energy storage for the following applications:

1. energy arbitrage in support of the grid alone

2. load shifting for utility-scale PV energy production

3. rapid ramp response to mitigate the effect of weather intermittency

4. power regulation

The design of an energy storage system for backing up single-axis tracking PV is presented. The system which consists of a combination of lithium-ion batteries with a new small-scale quasi-adiabatic CAES (compressed air energy storage) engine is being fabricated at the University of Arizona’s Solar Zone in partnership with TEP, Science Foundation Arizona and the Department of Energy.