Energy storage, and battery storage in particular, is the obvious solution to the challenge/ impact of this very high penetration of wind and solar is the weather-dependent variation in power output and more generally for other issues of electricity system operations. The rapid growth in both wind and solar has taken policymakers and electricity network operators by surprise in many countries in recent years. In the past, the distribution grid was a system which took the energy from source to customer; in the future, its major contribution will probably be through guaranteeing a secure supply. Compared with grid investments, battery-storage options have the advantage that they can in principle be moved. Batteries can be, and have been, installed in substations to avoid actual or forecast overloads of transformers; for example, to delay the need for reinforcement. This is particularly attractive for city-centre locations where land costs are high, space is restricted, and permitting processes may be prone to substantial delays. When the reinforcement is eventually implemented, the battery can then be removed relatively easily and used in another location.
Energy storage: Until recently, pumped-hydro storage was by far the dominant source of energy storage on electricity systems. Other technologies such as batteries, flywheels and compressed-air storage in caverns were insignificant in comparison. However, developments in new battery chemistries and other battery technologies such as flows through storage batteries and liquid air energy storage have changed this picture.
Consequently, transmission system operators and regulators are already working on actions to ensure that in future with a lower proportion of synchronous generators, they can keep frequency within limits and maintain operational security. Energy storage can contribute to resolving this issue.
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