Possibly power-to-gas. Methane production at 75% efficiency has been demonstrated a while ago[1] and claims of potential round-trip efficencies of up to 80% hav

Possibly power-to-gas. Methane production at 75% efficiency has been demonstrated a while ago[1] and claims of potential round-trip efficencies of up to 80% have been made[2]. This is relevant because Germany's existing gas infrastructure can store several hundreds of TWh. [1] https://www.kit.edu/kit/english/pi_2018_009_power-to-gas-with-high-efficiency.php https://www.kit.edu/kit/english/pi_2018_009_power-to-gas-wit... [2] https://www.sciencedirect.com/science/article/pii/S0360544218320693 https://www.sciencedirect.com/science/article/pii/S036054421...