Techno-economic analysis of energy storage systems for grid ancillary services

In a future with a higher renewable penetration, energy storage technologies will play an important role. They may, for example, use curtailed energy for arbitrage or supply ancillary services, help in relieving the grid congestion, and promote distributed generation. A techno-economic understanding and comparison between several electrical energy storage options is pursued as the main objective. Technologies with particular interest are: pumped hydropower storage, compressed air energy storage (CAES), several kinds of batteries (i.e. lead–acid, NaS, Li-ion), vanadium redox flow batteries, flywheels, capacitors and hydrogen. Special emphasis is put in the latest, as in a few years it may be one of the most suitable technologies for long term storage. After commenting these storage systems technically, an approach to ancillary services for southern California is made, considering them as a profitable use for energy storage technologies. Further life-cycle cost-benefit analysis of these electricity storage systems is done, taking into account several sources for cost data, providing an updated database for the cost elements (capital costs, operational and maintenance costs, and replacement costs)