The BIGGEST problem with clean energy

Excellent topic, depth and breath of summarization. Thank you for this. You might try to give more info on cost-effectiveness of the various technologies for various usage cases, such as short-term peaks vs. longer-term storage for exceptional seasonal peaks. For example, converting solar based electricity to hydrogen via electrolysis at 70% efficiency and then back to electricity with a fuel cell at 50% efficiency is a combined round-trip efficiency of only 35% - not so good, particularly if the cost of the electrolyzing equipment, hydrogen storage and fuel cell is high. Fuel cells also have a short-life problem for the membrane, as well as high maintenance / short-life issues for other components.