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What you say makes sense. But what if we need to generate 50 times more electricity than we do now? At some point solar and wind energy will start being very ex

What you say makes sense. But what if we need to generate 50 times more electricity than we do now? At some point solar and wind energy will start being very expensive because we'll run out of cheap land. You might think 50 is absurd, but consider this: 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. Then we want to increase everyone's standards of living to match the current standard of living of the average American or European person. That's another factor of 3. Then we want to increase our (clean) energy use. 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. AI will also consume a lot of electricity. We will also need to build cities, if we are to lift billions of people out of their current rural life (in Africa, South America, India, etc). Everybody talks about solar as if the goal is to replace the current generation capacity. But the goal is to do that, and then more, much, much more. I think you need nuclear for that.

bryanlarsen 2y ago
> 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.
- credit_guy 2y ago
  > Yes that might happen. But it'll happen at a number much greater than 50X. It's difficult to say. We are not running out of land, that's for sure. But we are running out of cheap land. Or rather land where it is economical to build solar. Sahara has plenty of empty land, and it is plenty sunny all year long, but there are civil wars more often than not, various militias, corrupt governments, etc. The US has lots of deserts, but also lots of groups with various agendas that find ways to delay projects, and delays can transform good projects into bad projects. As a concrete example, take California. California is very proud to be a leader in environmental issues. You can find on the state website the installed capacity per year. For the last 5 years it has been [1], in GW: 1.2 (in 2020), 1.5, 2.0, 2.3, 0.9 (in 2024, so far). The year over year growth rates were 26%, 35%, 10% and for this year -60%. This year is not over, and it's possible the numbers are not up to date, but it's quite unlikely we'll get to match last year's numbers, let alone see a double digit growth. Or take Texas. Wikipedia has their annual numbers between 2007 and 2023 [2]. I did the math, and between 2007 and 2017 they experienced a 90% annual growth. Nice Moore's law at work there. For the next 4 years the average annual growth was 60%. And for the last 2 years, it was 28%. Nothing to sneeze at, but the trend is clear. Why, if the cost of the panels went down? > Thousands of flights per year Elon is not talking about thousands of flights per year. Thousands of flights per day. Millions per year. A million launches of 5 kT CO2e each equal 5 GT CO2 each. That's about 10% of the current worldwide emissions. Or about 30% of the current emissions that come from power generation. If we are to use synthetic fuel instead of fossil fuel, and you have a 30% efficiency of making synfuel (which is what a quick google search indicates), then you have a 2x increase in electricity needs. [1] https://www.californiadgstats.ca.gov/charts/ https://www.californiadgstats.ca.gov/charts/ [2] https://en.wikipedia.org/wiki/Solar_power_in_Texas https://en.wikipedia.org/wiki/Solar_power_in_Texas

bryanlarsen 2y ago

> 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.

credit_guy 2y ago
> Yes that might happen. But it'll happen at a number much greater than 50X. It's difficult to say. We are not running out of land, that's for sure. But we are running out of cheap land. Or rather land where it is economical to build solar. Sahara has plenty of empty land, and it is plenty sunny all year long, but there are civil wars more often than not, various militias, corrupt governments, etc. The US has lots of deserts, but also lots of groups with various agendas that find ways to delay projects, and delays can transform good projects into bad projects. As a concrete example, take California. California is very proud to be a leader in environmental issues. You can find on the state website the installed capacity per year. For the last 5 years it has been [1], in GW: 1.2 (in 2020), 1.5, 2.0, 2.3, 0.9 (in 2024, so far). The year over year growth rates were 26%, 35%, 10% and for this year -60%. This year is not over, and it's possible the numbers are not up to date, but it's quite unlikely we'll get to match last year's numbers, let alone see a double digit growth. Or take Texas. Wikipedia has their annual numbers between 2007 and 2023 [2]. I did the math, and between 2007 and 2017 they experienced a 90% annual growth. Nice Moore's law at work there. For the next 4 years the average annual growth was 60%. And for the last 2 years, it was 28%. Nothing to sneeze at, but the trend is clear. Why, if the cost of the panels went down? > Thousands of flights per year Elon is not talking about thousands of flights per year. Thousands of flights per day. Millions per year. A million launches of 5 kT CO2e each equal 5 GT CO2 each. That's about 10% of the current worldwide emissions. Or about 30% of the current emissions that come from power generation. If we are to use synthetic fuel instead of fossil fuel, and you have a 30% efficiency of making synfuel (which is what a quick google search indicates), then you have a 2x increase in electricity needs. [1] https://www.californiadgstats.ca.gov/charts/ https://www.californiadgstats.ca.gov/charts/ [2] https://en.wikipedia.org/wiki/Solar_power_in_Texas https://en.wikipedia.org/wiki/Solar_power_in_Texas