The conversion of hydrogen into methane requires carbon dioxide (CO2). This is obtained, for example, from exhaust gases resulting from industrial processes or biogenic-fuelled power plants. If green hydrogen and green carbon dioxide are used for the reaction, the result is green methane. Since natural gas consists mainly of methane, the properties of both substances are comparable. Methane can therefore be easily fed into the existing natural gas network, transported and stored in existing gas storage facilities.