this post was submitted on 13 Oct 2023
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The thermodynamic minimum amount of energy needed to extract CO2 at 450 ppm is 120 kWh per tonne. Current experimental carbon capture plants run at about 5 % efficiency. If we assume we can double their efficiency and can magically produce as many plants as we need, to remove 20 Gt of CO2 per year (half our emissions) we would need 24,000 TWh of energy per year.
That is the entirety of the world's electricity production. To remove half our emissions.
Carbon capture is a non-runner.
Hemp. Nature provides a way to do many things that technology can't do efficiently. Hemp will capture carbon and store 80% in the roots. We would need 5 billion acres of hemp production to remove double our current emissions, I did the math a year ago. That would only be achievable with floating greenhouses, as far as I can figure, but if we hit net zero, then hemp looks much more doable in terms of a long term solution.
Edit: Also marijuana, and we can still use both plants the way we currently do, just store the roots in drums and fill up Yucca Mountain, since we aren't storing nuclear waste there.
Thanks for an example of the numbers. And to point out, the entirety of the world's production of electricity is still over 60% from fossil fuels, so using that energy to undo emissions is ideally a wash, and realistically still an increase. And that's if we turned all of the energy to carbon removal from everything else, which would never happen.
Well yes, but isn't the point to use progressively less fossil fuels - net zero implies we get to a point where we stop making things worse.
From there, then we can start making things better.
Net zero is simply where the emissions we still are emitting are being countered by "something" to have a flatline of human sourced emissions total. Likely the same magic that the IPCC is still counting on, carbon removal tech. It's almost 2024 now and we're starting to see the accumulation of the damage we've done, mainly because things like the oceans have hidden it for so long and are now failing. Time is up.
We absolutely need to reduce fossil fuel use NOW, and as much as possible each year. The damage that will do to our society might be a price no one is willing to pay though, we're very heavily dependent on it, more and more each year. Just a linear decrease means in five years we better be down to 30 gigatons annual emissions, and five more down to 20 gigatons. There isn't a way to do that and keep our modern society (and the up and coming third world industrial countries).
Discussing a Catch-22 situation can become heated, because people don't want the problems pointed out to them without some answers to consider. I'm sorry I don't have any to give. Any that I've ever seen or been presented with are always false hopes, it's a big mess we humans have created.
We're in a bad way until we have ubiquitous fusion, widely adopted nuclear, or some other non-CO~2~ emitting energy.
And those are really tall orders. We need a Manhattan + Man on Moon level effort to even begin to turn this thing around and I'm not see the urgency or leadership from people who'd need to get things rolling.