You're right that energy costs need to be accounted for when examining a potential capture method. But this is so blindingly obvious that of course the researchers are doing it. It is always accounted for when they are making their claims. As a single example see this recent article[1]:
> A simple chemical model estimated the rate of weathering for the crushed rock based on the local soil conditions. They also calculated energy requirements based on distance from likely rock sources, as well as accounting for the energy mix available to run everything. (The more fossil fuel burned to carry out the work, the less CO2 removed from the atmosphere in the final accounting.)
If it was true that any carbon capture method that uses energy will emit more carbon that it captures, then the researchers wouldn't have bothered doing the research. Yet they have, and do. Carbon capture is a very good avenue of research for mitigating climate change in the near term as we transition to new power sources.
> If it was true that any carbon capture method that uses energy will emit more carbon that it captures
The only way this works is if it's using excess energy that wasn't produced by processes that emit carbon to start with. Run it on nuclear, solar, etc. and it can work. However, the grid is still awash with coal power! There's no way any machine is going to capture more carbon per KW consumed energy than the coal to produce that many KW emitted to start with.
So, does it makes sense to deploy this in areas with a ton of green energy available on the grid? Maybe... but those areas have lower PPM carbon in the air, so it's not the right place to run the machine anyway.
Perhaps instead of all this wasted effort and engineering time, we could just replace the damned coal plants and stop emitting carbon itself.
> So, does it makes sense to deploy this in areas with a ton of green energy available on the grid? Maybe... but those areas have lower PPM carbon in the air, so it's not the right place to run the machine anyway.
Global carbon dioxide concentrations are not evenly distributed, but the distribution has much more to do with climate patterns than where the emissions happened. The atmosphere is fairly well-mixed. Across the whole globe, concentrations are significantly higher than pre-industrial levels. Source: https://earthobservatory.nasa.gov/images/82142/global-patter...
> Perhaps instead of all this wasted effort and engineering time, we could just replace the damned coal plants and stop emitting carbon itself.
Once the world reaches net-zero emissions, we can't celebrate and say we've stopped the problem. We just stopped it from getting worse. Carbon dioxide stays in the atmosphere for centuries, if we want to return the climate to pre-industrial, massive negative emissions will eventually be necessary. Engineering work on negative emissions will not be wasted unless we give up on that goal completly.
> A simple chemical model estimated the rate of weathering for the crushed rock based on the local soil conditions. They also calculated energy requirements based on distance from likely rock sources, as well as accounting for the energy mix available to run everything. (The more fossil fuel burned to carry out the work, the less CO2 removed from the atmosphere in the final accounting.)
If it was true that any carbon capture method that uses energy will emit more carbon that it captures, then the researchers wouldn't have bothered doing the research. Yet they have, and do. Carbon capture is a very good avenue of research for mitigating climate change in the near term as we transition to new power sources.
[1] https://arstechnica.com/science/2020/07/spreading-rock-dust-...