- Period of storage and storage capacity with different technologies
Renewable energies are generated at irregular intervals
The full-scale supply with green electricity requires a large storage capacity and a long period of storage.
The goal of future energy systems is a sustainable full-scale supply based on renewable resources. Wind and solar energy are generated on a fluctuating basis. The fluctuations with renewable energies are caused by natural phenomena, which cannot be influenced: the seasons (12 months), general weather patterns (approx. 14 days), the position of the sun (1 day), local weather (any number of minutes).
Even so, renewable energies must be available everywhere and at all times for electricity, power, heat and mobility. The main problem is therefore storage: Large quantities of energy must be put into storage at the point in time at which they are produced, in order to be available when needed on a continuous and reliable basis.
In today's energy system, energy reserves are provided by storing fossil energy sources (oil, gas, coal). The amount of energy thus stored is typically enough to cover several months' consumption.
However, this does not apply to electricity. In Germany, the electricity storage capacity currently available is just 0.04 terawatt hours, which is the equivalent of less than one hour's electricity demand.
What is needed are storage capacities on a terawatt hour scale which can be used in the short term for a period of storage lasting from several weeks to several months.