Electric Energy Storage and its tasks in the integration of wide-scale renewable resources

The CIGRE committee on dispersed and distributed generation has recognised the future role of storage systems in the integration of renewable sources. Due to this fact in 2007 it founded the Working Group on electrical energy storage systems with the number WG C6.15. This paper summarizes the results of the investigation done by the WG during the last 2 years. The investigation is based on the national studies of EU in Canada, the USA, CIGRE and Germany, as well as on the data delivered by the international members of the WG. Diverse storage technologies are discussed. The study points out that in order to improve the integration of renewable generation more storage systems are required. The available technologies such as batteries-based storage systems become competitive if regarding new application especially corresponding to the integration of renewable and also in the correlation with mobility. The national studies, e.g. Germany or the USA, have identified some incentives for supporting these technologies in the future. The so called "storage bonus" - that is valued at 0,02 to 0,04 euro/kWh over 20 years - and investment tax credits are already discussed in Germany and USA respectively. A simulation with numerical results has shown that this concept is beneficial. It is important to mention that these new mechanisms are expected to be implemented into the renewable law, e.g. in Germany. Furthermore, the paper gives an overview of the potential for storage capacity related to the increase of renewable generation in different countries around the world.