In addition to wind and solar-based power generation, energy storage is the third building block for a mainly renewable energy supply. It ensures that wind and sun energy is available when it is needed.
However, that’s not all. Certain storage types such as batteries play another very important role: They stabilize the energy system. Combined with intelligent software they enable the flexible and demand-driven use of conventional generators.
Principally, post-fossil energy supply needs all types of storage: hourly, daily and in the long run also seasonal storage; it needs larger units as much as smaller storage systems very close to the consumer.
First stop: Short-term storage
However, during the initial phase of the transition to renewables, we need to be able to store comparatively large amounts of energy for small time periods such as minutes or hours. This ensures that – at a given point in time – we have just as much power as needed, thus keeping the grids in balance.
Only once we reach an annual share of approximately 60 percent of renewable energy, will we need significant daily storage capacities – in order to shift solar energy to the nights and storms into periods of calm winds. In order to increase the annual share of renewables above approximately 75 percent, we will ultimately also need seasonal storage systems that preserve energy for weeks and months.