It remains to be seen if carbon removal can be done in a way that makes sense thermodynamically (i.e. it takes tremendous energy input to do, where does that energy come from, is it using carbon-emitting energy from elsewhere on the grid, etc). If at any point a carbon-emitting energy source is involved, there's no way that the system is going to be absorbing as much carbon from the air as was emitted for the same amount of energy.
If we're going to flatten the peaks of power availability with anything, it should probably be novel energy storage techniques so that the carbon that is output is not wasted, so the energy is actually used eventually for something productive.
We already have a carbon removal system that is viciously efficient and solar powered: it's called a plant.
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.
Not so simple as just saying "plants" and calling it a day.
Yes, plants remove carbon from the air. But plants die, and rot, and some amount of that carbon (all, at the limit) ends up right back in the atmosphere.
I happen to think that planting poplar, making it into charcoal on an industrial scale, and using the biochar as a soil amendment to mitigate topsoil depletion, is severely underutilized as a carbon capture strategy. We should be doing enormous amounts of this, instead of... basically none.
But it isn't "just plant trees". There's more to the job than that. But nothing which requires technology which was unknown to the Romans.
I posted this on another thread in these comments but another strategy here is grow trees, bury trees, grow more trees. 3% re-release of carbon back to the atmosphere per dacade stored, and all the tech to accomplish it is already developed.
Enhanced Rock Weathering was discussed recently[1], and that is cost effective at something like $100/ton. I don’t think there is any question about whether it’s thermodynamically possible (trees do it, as you say), it’s more whether it’s economically possible; without a carbon tax there is no real incentive for most producers to offset. (If we are relying on demand from “ethical consumers” I don’t think we are going to shift things very far.)
If we're going to flatten the peaks of power availability with anything, it should probably be novel energy storage techniques so that the carbon that is output is not wasted, so the energy is actually used eventually for something productive.
We already have a carbon removal system that is viciously efficient and solar powered: it's called a plant.