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Comment by gridspy | Hacker News Reader

You say "likely never" but eventually we'll have covered the earth's surface in solar panels. Unless we are transitioning to space based solar and transmission we'll want fusion to increase energy generation beyond surface irradience of earth.

In the meantime, solar panels for massive generation also incur transmission costs to centralize that energy for any major energy usages. We might want to keep having high power generators next to super-high energy consumers. For instance our (theoretical) hyperspace communication and computation array. Right now those usages are things like Arc Furnaces, Aluminum smelters, data-centers, ...

Plus, we'll want to have figured out that fusion tech so we can build it into our spaceships travelling out beyond Mars as an energy source and hopefully also a thrust source. We want to master that tech on Earth's surface for sure.

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> You say "likely never" but eventually we'll have covered the earth's surface in solar panels. Unless we are transitioning to space based solar and transmission we'll want fusion to increase energy generation beyond surface irradience of earth.

> In the meantime, solar panels for massive generation also incur transmission costs to centralize that energy for any major energy usages. We might want to keep having high power generators next to super-high energy consumers. For instance our (theoretical) hyperspace communication and computation array. Right now those usages are things like Arc Furnaces, Aluminum smelters, data-centers, ...

Well before we cover the entire globe in PV, the mere fact that the panels absorb a lot of light means they will change the planet's albedo, heating things up.

But any source of power on that scale will also increase the planet's equilibrium temperature (regardless of if it's PV, fusion, or even if we figure out how to harness dark energy/zero point shenanigans) so we want space-based power before then — and the industrial capacity to use that power in space, because simply beaming it down to Earth is still going to heat up the planet just like any other power source.

Before we even get to that point (in fact, already today) humanity is manufacturing enough metal to make a global power grid with only 1 Ω of resistance the long way around. The limiting factor is geopolitical, not technical, because it's literally just China making enough of the relevant metals.

> covered the earth's surface

In any discussion of far-future considerations like this we need to remember that thermodynamics requires all energy used for work to become heat. Covering the Earth's surface in solar panels is one thing, but by the time we're covering every inch in fusion power plants, we've turned the Earth's surface to lava from all the waste heat. There's a physical upper bound on energy usage within the Earth's biosphere that prevents useful energy production from scaling to infinity, and as a result we'll find ourselves optimizing for economics rather than being limited by energy production per unit of area.

As for industry, yes, it seems likely that industry will still represent a large and relatively centralized consumer of power which may benefit from a large dedicated installation. But I'm not convinced that fusion will ever be more economical than even traditional nuclear fission energy (just because your fuel is relatively cheap doesn't mean a thing if the plant itself is essentially disposable because of the energies involved).

As for space, maybe, though considerations of space exploration aren't driven by economics, so whether or not anybody ever figures out a viable fusion reactor design for a spaceship could have as little relevance to civilian power generation as your classic RTG did.

Plot twist: the death star was originally conceived as a contraption to regulate waste heat in artificial planets.

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