Germany is using some 40 caves for natural gas storage at the moment. Together, they share a volume of 23.5 billion cubic metres and 400 000 kilometres gas grid.
Adding hydrogen to these caves, a concept called power-to-gas, could be yet another way to store renewable energy. The European Group on the Gas Research, or GREG, estimates that about 6-20% of the mix could consist of hydrogen.
Hydrogen from renewable sources is mainly produced by electrolysis, and could be used in CCGT (combined cycle gas turbines) or CHP (combined heat and power) via fuel cells, for example.
Germany is best positioned to take up such a lead, because of its large share of renewable energy in the total energy mix. Renewables account for 20% of all energy produced today, and is expected to rise to 50% by 2030 and 80% by 2050.