It depends on the method. IIRC, the most cost effective methods cost more than leaving it there. The real problem really is figuring out how to make a profit off it. Without the government forcing it subsidizing it, nobody will do it, even sustainably, in volume enough to matter.
Casey Handmer seems to think there’s still an opportunity here. There are updated versions of that post, but I think this was his first on the topic.
Targeting the preindustrial level of atmospheric CO2 is such an ambitious target, trying to undo 300 years of emissions. Then again, it’s not like we’ve stopped emitting.
If we instead try to calculate the energy requirements to simply offset the average emissions of that particular year, using this formula of 652 kJ/kg CO2, and average annual CO2 emissions, against the current numbers of about 37 billion tonnes, or 37,000,000,000,000 kg, we have 2.4 x 10^16 kJ, or 2.4 x 10^19 joules. Which converts to 6.7 x 10^12 kWh, or 6,700 TWh.
Total annual US electricity generation is about 4700 TWh per year.
Global electricity generation is about 25000 TWh per year, about 40% of which is from low or zero carbon sources.
So basically if we’ve got 6700 TWh of clean energy to spare, it would be more effective to steer that into replacing fossil fuels first, and then once we hit a point of diminishing returns there, explore the much less efficient options of direct capture for excess energy we can’t store or transport. Maybe we’ll get there in a decade or two, but for now it doesn’t make any sense.
If we wanted to remove enough CO2 to get back to the preindustrial level of 280 ppm, it would take 2.39 x 10^20 joules of energy. For a reality check, that’s almost as much as the world’s total annual energy consumption (5.8 x 10^21 joules every year).
Isn’t that over an order of magnitude difference? What am I missing? How is that “almost as much”?
The problem is that this is a theoretical minimum, not an actual, proposed process. We’d need a way to attract CO2 to separate it from the rest of the air, and afaik that doesn’t exist. Any actual process is likely to be far less than 100% efficient, probably an order of magnitude or more less.
This is an example of a real proposal, but I have no idea how efficient it is. It would be a lot more helpful if this article provided a realistic example instead of some back-of-the-napkin math.
We’d need a way to attract CO2 to separate it from the rest of the air, and afaik that doesn’t exist.
Call me crazy but what about plants and trees?! 🤷🏼♂️
They might not be 100% efficient but it’s dirt cheap to plant them, let alone not destroy the rest we still have
Oh yeah, I agree it’s super inefficient currently. But if the theoretical 100% efficient process is 5% of our current yearly energy expenditure, that sounds promising and suggests we shouldn’t just write off the idea.
Exactly. I want to see some investment into CO2 removal. If that’s cheaper than retooling everything, we should do it. If it’s not, we should do a little bit of it to help remove the negatives of climate change as we transition to a more responsible society.
I say we tax carbon emissions at around the theoretical removal cost, and then use some of that to invest in removal tech.
I didn’t read the article but it seems off. With only 1/20 of energy used by the world in a single year we could undo the damage of 300 years?
Seems too low. If that’s true we could shut down completely for just two weeks to undo
Can’t imagine “shutting down completely for just two weeks” would exactly be reasonable, but yeah I wonder if the article had a typo in it. I’m not sure. As of right now, the numbers are still the same in the article.
If the numbers are correct, expending like 5-10% of our energy expenditure for a single year on carbon capture sounds a lot more reasonable than the article suggests. Even if it were half of our yearly energy usage, that sounds pretty reasonable if you draw that out over a few decades.
I’m guessing they don’t understand scientific notation, and “numbers are close” without understanding the numbers are much more significant
That’s honestly pretty good, I can see world leaders coming together and just doing that. There must be other technical challenges to this other than raw power usage
I don’t know much about the technology, so I can’t comment on that. But I don’t really see politicians pushing for this, at least not succesfully. There are too many rightwing obstructionists in most Western governments right now…
None. They are called trees. We should stop wrecking things.
To be fair trees still use energy for doing this, but that energy is conveniently provided by the sun.
