Energy storage in future power systems

Most sources of renewable power are characterised by uncontrollable and chaotic variations in power output. We here look at how energy storage may benefit renewable power generation by making it available in periods with little or no intermittent generation and thereby prevent additional conventional generation form being used. In addition to this, one of the strongest concerns in relation to renewable power is the instability in the electric power system that it may introduce as a result of large and relatively fast power fluctuations. An additional benefit of energy storage is therefore its ability to counteract fluctuations in renewable power generation and thereby allow for longer reaction times for any controllable generation units. Capture and storage of excess renewable power in order to fully exploit the natural recourses is likely to become relevant for high penetration levels of renewable energy. Meanwhile, the insurance of power system stability through reduction of power gradients is of major importance even at lower penetration levels and some form of energy storage therefore seems unavoidable. A variety of technologies are available for storage of energy in the power system. When identifying the most relevant storage solutions it is necessary to include considerations on many relevant parameters which should be evaluated against the potential drawbacks and benefits of adding storage. Here, the most relevant technologies in relation to power systems with high penetration of renewable sources are identified and considerations with regard to cost, sizing and operation scheme are made.