by miguelazo on 6/9/24, 4:06 PM with 41 comments
by jandrewrogers on 6/9/24, 5:02 PM
This still leaves the problem that the industrial plant and chemical feedstock required to physically do the DAC at the scale of billions of tons per year is several orders of magnitude beyond what is possible with current supply chains and natural resources. You would have to strip mine the planet just to have the raw materials to build the necessary DAC infrastructure, and we need those resources for other critical things as well.
Some proposed DAC chemistries have upstream mineral dependencies that, if done at the scale required just to offset a year's emissions, would consume all known global reserves immediately. This is not solved by recycling because of compounding loss rates; recycling is not 100% efficient, and the amount of energy required to improve recycling efficiency is essentially exponential for rapidly diminishing returns, and we already have an energy problem with DAC.
DAC at any scale that is not an exercise in futility will be an exercise in environmental and economic destruction at unprecedented scale. The solution would almost certainly be worse than the problem. There really isn't a path forward that doesn't involve dramatically reducing emissions and letting nature remove the excess carbon.
by downWidOutaFite on 6/9/24, 5:02 PM
by danans on 6/9/24, 4:49 PM
by ceruleanseas on 6/9/24, 4:35 PM
I think this may be similar, in that maybe the current solutions are not going to solve the problem, but by investing in these, in the long run, they may prove to be necessary as we get better at it.
by hinkley on 6/9/24, 6:10 PM
by dave4420 on 6/9/24, 4:27 PM
by DennisP on 6/9/24, 5:22 PM
In terms of energy, some emerging tech is pretty close to ideal. Princeton has a project they claim can do 0.7 gigajoule/ton, or 195kWh [1]. And MIT is claiming one gigajoule/ton, or 278kWh [2].
If we transition to a wind/solar/battery grid, the cheapest option in the US at least is to have about four days of battery and 2X overproduction [3]. So that's a lot of extra energy basically available for free. Even today, with relatively small usage of renewables, utilities sometimes let electricity costs go negative [4]. If capital costs aren't too high, then DAC can run whenever there's excess energy available.
Of course, capital cost will be a big portion of the expense, though it'll decrease as we scale. Climeworks and Carbon Engineering have estimated $100/ton in total cost, which equates to a dollar per gallon of gasoline. Many places already have gas taxes higher than that. And the MIT and Princeton methods should be cheaper at scale than current methods would be.
Actually eliminating all our annual emissions by just doing this would of course be madness. But if we tried, and charged emitters for doing that, then most emitters would find it cheaper to stop emitting instead. Then we'd naturally end up only using DAC for emission sources that are very hard to eliminate.
After we hit net zero, we'd be smart to take CO2 down to a safe level. Call it 100ppm of reduction. Hopefully we can do some of that with reforestation and so on, but let's say DAC is our only option. One ppm is 7.8 gigatons CO2, so we're talking 780 gigatons to draw down. At 200kWh/ton that's 156 TWh, not far off from the world's entire energy usage for a year, matching the article's estimate.
But if we're at 2X overproduction on energy, then we'll have that much energy available. Only the capital cost of the equipment would really be important, and by the time we scale it that far, that should be fairly low too. The methods I linked use cheap, readily available materials.
So it looks pretty feasible to me. We can call this a "distraction" and put up with the terrible consequences of whatever high CO2 level we reach by the time we're at net zero, or we add DAC to a wind/solar/battery world and get down to a nice cool 350ppm. Since it takes time to scale, and climate feedbacks give us a time limit, we need to develop and start scaling DAC now.
[1] https://engineering.princeton.edu/news/2024/03/14/engineers-...
[2] https://news.mit.edu/2019/mit-engineers-develop-new-way-remo...
[3] https://caseyhandmer.wordpress.com/2023/07/12/grid-storage-b...
by kjkjadksj on 6/9/24, 5:14 PM
by gmuslera on 6/9/24, 4:57 PM
Anyway, CO2 capture, by itself, is not the whole solution, but it should be part of it. There is an unbalance between the energy that comes in and the one that goes out. so things heats up (among other negative consequences, like i.e. ocean acidification). You won't solve the whole problem without addressing that eventually, so some way of carbon capture, going through the use of energy or something else, should be in the map.
And the complementary part of that is stop adding new (or, in other way to see it, very old, but that was stored away) carbon to the system. Even with the very worrying signs of the global climate going haywire with the corresponding loses of lives and money we keep adding each year even more fossil carbon than the previous one, no matter how much token energy generation is announced to be done by other means.
It may be expensive, or require technologies that we don't have yet, or compromises on what to lose, or whatever, but it is a problem that if left by its own means will eventually make the planet unlivable for us in a way or another. And that will turn all the saved money into something meaningless.
by tmnvix on 6/9/24, 9:12 PM
Trees.