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Comment by fulafel | Hacker News Reader

The uranium in seawater is same as uranium in the ground, not renewable.

Uranium in seawater is available in much larger quantities. We would not consume the amount of uranium over the next billion years even if we used nuclear for all of humanity's energy demands [1]. It is renewable in all but the most literal sense.

Uranium in seawater is the same as the hydrogen in the sun: it's not renewable. The hydrogen in the sun will eventually be fused to such an extent that no further energy will be released. There is no such thing as a renewable energy source because the laws of thermodynamics dictate that there is a finite amount of usable energy in the universe.

https://www.forbes.com/sites/jamesconca/2016/07/01/uranium-s...

Renewable in the context of energy policy means that it continuously renews on Earth on human timescales.

I agree that with uranium it's not really relevant in practice due to the large supply of it.

While I agree with you that it's virtually impossible for humans to use up the uranium in sea water at our current energy consumption rate, I think it's worth thinking about that if we had "unlimited" energy, we might use orders of magnitude more of it than we currently do.

That being said, for that to be an issue, we'd have to increase our energy consumption at least 1000x, and if we get to the point of using that much energy, it seems likely we'll also have advanced technologically to such an extent that we'll figure out another solution. It's just an interesting exercise to consider how what seems impossible today, might be totally routine in 10/100/1000 years.

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