Compressed air has been around for centuries, but: """ While pumped hydropower storage has a charge/discharge efficiency of 70-85%, and chemical batteries reac

Compressed air has been around for centuries, but: """ While pumped hydropower storage has a charge/discharge efficiency of 70-85%, and chemical batteries reach 65-90%, the CAES plants in operation in Germany and the US have an electric-to-electric efficiency of only 40-42% and 51-54%, respectively """ http://www.lowtechmagazine.com/2018/05/history-and-future-of-the-compressed-air-economy.html http://www.lowtechmagazine.com/2018/05/history-and-future-of...