3 ms·

If it's just salt then it's basically just a matter of figuring out how much seawater we need to evaporate. Which we can find out by dividing the total energy c

If it's just salt then it's basically just a matter of figuring out how much seawater we need to evaporate. Which we can find out by dividing the total energy consumption by the energy density of hydrogen [1], this results in a figure of 120 tons a year, or about 2.8 billionth of the ocean [2], or about .001 cm a year [3] (until the area of the ocean starts shrink noticeably). Assuming the evaporated water returns to the ocean after a while I reckon we should be fine. [1]: https://www.wolframalpha.com/input/?i=%28world+energy+consumption+%2F+hydrogen+heat+of+combustion%29 https://www.wolframalpha.com/input/?i=%28world+energy+consum... [2]: https://www.wolframalpha.com/input/?i=%28world+energy+consumption+%2F+hydrogen+heat+of+combustion%29+%2F+%28density+of+water+*+volume+of+the+ocean%29 https://www.wolframalpha.com/input/?i=%28world+energy+consum... [3]: https://www.wolframalpha.com/input/?i=%28world+energy+consumption+%2F+hydrogen+heat+of+combustion%29+%2F+%28density+of+water+*+area+of+the+ocean%29 https://www.wolframalpha.com/input/?i=%28world+energy+consum...

darksaints 7y ago
I believe you meant to say 120 tons per second. Your [1] link shows 3.8x10^15 grams, which is 3.8x10^9 (metric) tons, not 120. That is in mass of hydrogen. Multiply by ~9 to get the total mass of water used to electrolyze that quantity of hydrogen. However, the water cycle is pretty fast on average, and has incredibly high throughput, and the cycle quickens as water vapor concentrations increase. If hydrogen generation is sufficiently distributed, you could likely just wait for the next rainfall to release the brine.
- contravariant 7y ago
  You're right I seem to have misread. Good point about the factor ~9, but even then it doesn't look like we'll be draining the oceans dry any time soon. Although it would be a problem of unimaginable scale to use it as the sole source of energy, which is bound to create some of its own problems, I just don't see any obvious ones.

darksaints 7y ago

I believe you meant to say 120 tons per second. Your [1] link shows 3.8x10^15 grams, which is 3.8x10^9 (metric) tons, not 120. That is in mass of hydrogen. Multiply by ~9 to get the total mass of water used to electrolyze that quantity of hydrogen. However, the water cycle is pretty fast on average, and has incredibly high throughput, and the cycle quickens as water vapor concentrations increase. If hydrogen generation is sufficiently distributed, you could likely just wait for the next rainfall to release the brine.

contravariant 7y ago
You're right I seem to have misread. Good point about the factor ~9, but even then it doesn't look like we'll be draining the oceans dry any time soon. Although it would be a problem of unimaginable scale to use it as the sole source of energy, which is bound to create some of its own problems, I just don't see any obvious ones.