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> Theres no scenario I can think of where it actually makes sense to use 5000 units of energy to clean up the CO2 generated by the production of 100 units of energy

This line of thinking comes from the fossil fuel industry. Nobody in clean tech advocates for this.

The problem is that even if we get to net zero by 2050, there will be too much carbon in the atmosphere. Global warming is actually suppressed by aerosols emitted by coal and other fossil fuels, and is going to get much worse even if we meet energy transition commitments. Further, there are industries that we don't know how to decarbonize (e.g., aviation, sustaining need for things like plastics).

Carbon capture (point source and direct air, whether for storage or for reuse) are logically sound. They are extremely expensive (thermodynamically, resource, $) and basically nobody likes them, but humanity lacks better solutions.

This process addresses a different problem than electric cars do. It produces aviation fuel that is usable by existing long range aircraft. There is no battery powered alternative to an Airbus A330 or Boeing 777.

I address this in my comment though. CO2 is fungible, it does not matter what is producing CO2, all that matters is the net CO2 produced. If it takes 5000 units of solar power to produce 100 units of fuel for airplanes, it is completely stupid to do that when just not making the airplane fuel lets you take 5000 units of coal power production offline with no additional steps.

Saying it another way: If you use the 5000 units of solar or wind power to make jet fuel, that is 5000 units of solar or wind power you can't use to shut down 5000 units of coal power.

Let me break it down for you:

  Use solar to make jet fuel:
  5000 units of net CO2 from coal plant to make electricity.
  0 units of net CO2 from synthetic jet fuel.

  Use solar to make electricity:
  0 units of net CO2 from coal plant that isn't necessary because solar instead.
  +100 units of net CO2 from regular jet fuel.

Your hypothetical isn't actually happening.

Power generation dedicated to green fuel production is already being built in places that aren't readily connected to grids.

Further, we already curtail, for lack of demand and storage. More so over time. Better to use that excess power. Like for making green fuels.

Name a place there is significant power generation with no access to the grid? This is not a thing.

> well below the CO2 production level to avoid warming

The warming already happened and will continue to worsen.

We must reduce atmospheric CO2 to below 350ppm to stop, and hopefully reverse, the warming.

We need green fuels to hit net zero. And once the remaining use cases are decarbonized, we'll pump those fuels into the ground for net negative.

What if the 5000 units of energy were created from solar?

I think all these "generate something which can be buffered and stored" projects are interesting. A big problem with solar and wind is the transmission and intermittent nature. If the power can instead be stored as hydrogen for use in industrial processes or as jet fuel, that's great!

right, so use the solar to split hydrogen/oxygen from water and store it. hell, while you're at it, desalinate the water and burn the salt for more heat.

Burn the salt... ? :-D

Then you use the 5000 units of energy and just not make the co2???

I was thinking in chess moves so looking a few moves ahead rather than just what's in front of us now. Use this in conjunction with a CO2 extractor from the atmo, and now you're getting a 2-for-1 of the "clean".

No, your 3d-chess doesn't make sense. If you use the power to pull CO2 out of the atmosphere, then you don't have the power anymore.

No, you just put up another 5000 unit panel. Nobody said the same 5000 units had to be shared.

If you build an additional 5000 units then you could still use that to offset 5000 units of coal. You can keep doing this until there is no coal left. When there is no coal power, and no gas power, and no oil power, then finally you are right. How is this point not clear?