[throw_away1525]

DAC makes no sense from an energy accounting perspective.

Simple argument: DAC requires energy.

In some places, that energy is stranded. Think of the DAC plant in Iceland using geothermal. Fine. In that case, DAC makes a meaningful contribution.

If the energy used for DAC is not stranded and could instead be used to offset fossil fuels, it would be far better to offset the fossil fuel use. This is trivially proven true when you consider the 2nd law of thermodynamics. Better to prevent the entropy increase from adding CO2 to the atmosphere in the first place.

Therefore, attempting to use DAC to mitigate climate change while fossil fuels are still being burned is pointless. If you can build the energy infrastructure you will need to power DAC, you would be far better off just using it to offset and eliminate fossil fuel use.

Once you have eliminated the use of fossil fuels, sure, DAC makes sense. But the idea that DAC will save or even help us without complete decarbonization as a prerequisite is just nonsense in my opinion.

[tzs]

The atmosphere does a pretty good job of mixing, with the CO2 concentration uniform to within +/- 1% around most of the world so if there are enough places with stranded energy just building DAC plants there could help the whole world.

If there aren't enough places with stranded energy maybe we can make more. All that takes is installing more solar in some place than there is infrastructure to transport the electricity out. That excess is stranded.

The amount of energy available for solar is insane. To illustrate how ridiculously abundant solar power if you wanted to build a solar farm whose output during the day matched the power use of the entire world you'd only need about 500 000 km^2 worth of panels.

At night the power falls to near zero, but so what? If all it is doing is running a DAC plant it doesn't need to run overnight.

I'm sure there are hundreds of places around the world with good daytime sunlight, enough room for a DAC plant and a solar farm to power it, and limited grid infrastructure.

[mucle6]

"Only" need about France (~551,000 km^2) worth of panels. I see your point though

[Maursault]

> Therefore, attempting to use DAC to mitigate climate change while fossil fuels are still being burned is pointless.

Because no one has suggested using DAC to offset fossil fuel use without reducing fossil fuel use, this is a straw man. DAC may very well be a valid strategy when used in conjunction with the reduction of fossil fuels to better reduce the amount of atmospheric carbon in a given time frame.

[Paul-Craft]

Nobody seems to be doing anything to reduce emissions, either. Except for the blip due to COVID, globally, we're still on the same trend we have been forever: https://ourworldindata.org/co2-emissions

[bryanlarsen]

I don't think any of the realistic models have DAC providing a significant percentage of the carbon reduction. For example, 99% of the reduction from green electrification, and 1% from DAC.

DAC is still in the research phase, and is probably a decade a way from widespread use.

Solar power, wind power and electric transportation are already well into the production phase and are happening today.