Lithium energitab: https://royalsociety.org/-/media/policy/projects/synthetic-fuels/synthetic-fuels-briefing.pdf Pumped hydro energitab: https://www.sciencedirect.com/science/article/pii/S0360544217314822#fig1 se figur 3 Brint energitab: https://www.sciencedirect.com/science/article/pii/S235248471830266X