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Am I the only one who worries that if this is implemented at industrial scale, then 100 years down the line we'll be facing a new ecological catastrophe when we

• credit_guy 4y ago
  It's absolutely impossible to deplete a significant, or even an insignificant portion of the world ocean. To get a feel or it, it's useful to think in terms of cubic kilometers. A cubic kilometer of water weighs a billion tons (1 GT). The world consumes every year something of the order of 10 GT of fossil fuel (about 5 GT of coal and 5GT of petroleum and natural gas). Hydrogen has a higher energy density than fossil fuels (by a factor of 2 or 3). But only 10% of the water by weight is hydrogen. So, to get one GT of hydrogen you need to electrolize about 10 cubic kilometers of water. Let's say you want to fully replace all the fossil fuels with hydrogen, and then have room for further growth. 10 GT of hydrogen/year will be more than enough regardless how you project that growth. That would be 100 cubic kilometers per year, or 10000 cubic kilometers per century. The volume of the world's oceans is 1.3 billion cubic kilometers. You just used less than 0.001% of that. But actually you didn't. Because all the hydrogen you've produced and then burned to generate electricity ends up as water vapors, which after a bit of travel in the atmosphere become clouds, then rain, then end up right back in the oceans.