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It is absolutely trivial that separating hydrogen from water uses energy. Then, when you burn it, you get water and energy back. That is the whole point.
by ncmncm 4y ago
It is absolutely trivial that separating hydrogen from water uses energy. Then, when you burn it, you get water and energy back. That is the whole point.
- wh33zle 4y agoThat is trivial yes and I was well aware of that :) What wasn't obvious to me from the parent comment was why it is apparently completely impractical. No energy conversion has an efficiency of 100% so the answer couldn't just have been "because thermodynamics" but as other comments have since revealed, it is because _current_ hydrolyzers only operate on an efficiency scale of 60-80%.
- ncmncm 4y agoAnd, turbines and fuel cells are also at ~40-60%. So, round-trip is a fair bit lower than that, as little as 25%. But it doesn't matter much. Efficiency is improving, and will be much better before anything depends on it. What do you imagine is the raw efficiency of making hydrogen from. NG, vs the enthalpy of the input gas? BTW, "electrolysers". Hydrolysis is a thing plants do.