Comparison of large-scale energy storage technologies

In this paper, technologies are analysed that exhibit potential for mechanical and chemical energy storage on a grid scale. Those considered here are pumped storage hydropower plants, compressed air energy storage and hydrogen storage facilities. These are assessed and compared under economic criteria to answer the question of which technology is to be favoured. For this purpose, the levelised electricity cost for various dispatch scenarios – short-, medium- and long-term storage – are calculated for the present and for 2030. Fundamental indicators considered are their respective efficiencies, capital expenditure and operational expenditure, and technical service lives. From an economic point of view, today pumped hydro is the most cost-efficient short- and medium-term storage technology, closely followed by compressed air energy storage. In the future, too, there will be no fundamental change in this result, even with optimistic assumptions for the development of hydrogen storage. However, hydrogen storage is becoming more competitive and represents the most economic option in the future for long-term energy storage.