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On the Role of Storage Integration in Smart Energy Systems

Larger shares of renewable energy sources (RES) are considered as a precondition for heading towards sustainable electricity systems. In recent years electricity generation from variable sources like wind and solar has rised. To balance electricity supply over time calls for storages has been launched. Storage has played an important role for balancing generation and demand at least to some extent since the beginning of electricity systems with pumped hydro storage This balancing has to be done over short – e.g. hours, days – and longer periods e.g. months and year. The core objective of this paper is to investigate the future market prospects of long-term – as hydro pump storages, and power-to-gas (PtG) technologies like hydrogen (H2) and methane (CH4) – and short-term battery storage from an economic point-of-view. In this context it is very important to analyze especially the long-term Learning effects regarding the investment costs of all relevant technologies. The major results and conclusions are: (i) Despite many calls for a prophylactic construction of new storage capacities with respect to all centralized long-term storage technologies the future perspectives will be much less promising than currently indicated in several papers and discussions; (ii) new long term hydro storages will not become economically attractive in general in the next decades; however, daily storages will remain the cheapest option and the most likely to be competitive; (iii) batteries has the advantage that they do no compete with the low price spreads in the wholesale markets but with the considerably higher retail prices for electricity (between 20 and 30 cent/kWh in Western Europe); (iv) For PtG-technologies it will also become very hard to compete in the electricity markets despite a high technological learning potential. Yet, for hydrogen and methane there are prospects for use in the transport sector. Fuel prices in transport in recent years have rather increased compared to stagnation or decreases in electricity spot markets. Consequently, and given in addition the lack of environmentally benign fuels for mobility hydrogen and methane from renewable electricity might become an economically alternative for fueling passenger cars. However, in any case new storages should be constructed only in a coordinated way and if there is a clear sign for new excess production, in this case of RES.