> At some point solar and wind energy will start being very expensive because we'll run out of cheap land.
Yes that might happen. But it'll happen at a number much greater than 50X. And it's a problem that'll only happen if we solve the global warming problem first.
> right now only about 30% of our energy consumption (and therefore emissions) is electricity. If we want to cut emissions to zero, we need to transition most of our energy use to electricity. The big culprits are transportation, steel, concrete and fertilizers. That's a factor of 3.
But we mostly use fuels that are 30% - 60% efficient plus wastage for production, refining and transporting. Over 2/3rds of the energy we use gets wasted as heat. So we've got a factor of 1/3 to cancel out your 3 here. It's not completely efficient so it's actually about 1.2X, not 3X.
> Then we want to increase everyone's standards of living to match the current standard of living of the average American or European person.
Yep, that's a good 3X, if not more there. But unfortunately it's going to take decades to accomplish this.
> Each SpaceX Starship launch puts about 5000 tons of CO2-equivalent emissions in the atmosphere. If, as Elon wants, we end up having hundreds or thousands of launches per day, and we want these launches to be net zero, then we need to find a way to manufacture hundreds of millions of tons of synthetic fuel each year.
> Each SpaceX Starship launch puts about 5000 tons of CO2-equivalent emissions
Each launch would then be a 0.00001X, and is approximately equivalent to a trans-pacific plane flight. Thousands of flights per year would not be a significant fraction of the Earth's emissions. Hundreds of thousands of flights would be.
- solar is fine up to around 500X
- which won't happen this century
- when it happens power will be abundant enough that the cost calculations will be radically different
- technology will also be radically different. Maybe we'll use anti-matter reactors or something.
