The map shows the maximum available gas storage capacity in the EU expressed in terawatt-hours (Twh). A terawatt-hour is a unit of energy equal to outputting one trillion watts for one hour. The bar chart shows the gas storage filling rate, or the percentage of available storage that has been used to store gas. Data come from European Network of Transmission System Operators for Gas. In the EU, the maximum available storage is 1 106 Twh, with total energy stored of 437 Twh, giving a filling rate of 39 % overall. Countries with smaller capacity seem to have a higher filling rate. Portugal, for instance, has a maximum capacity of 3.6 Twh and a filling rate of 89 %. Germany, with the highest capacity of 237 Twh, has a filling rate of 41 %.