Underground Carbon Storage: The Gold Standard for Carbon Removal?
Grabbing on to carbon is the essential first step to take carbon out of the air. But as my friend Mac says, “what do you do with it once you’ve got it in your hot little hand?”
If you grab on to carbon dioxide and then let it go, it goes right back to heating up the planet. So once we capture carbon dioxide, we need to use it or store it. Using carbon is great. We should use every bit of carbon that we can. Fuels, plastics, and products. You can make a bracelet, you can make a building.
But what all the carbon we can’t use? Underground carbon storage seems crucial to pulling out gigaton of carbon. I’ve just recently got interested in carbon storage as part of Negative’s Kickstarter campaign. This piece is my exploration on carbon storage, and I welcome your comments!
Economics of Carbon Storage
Carbon storage is tricky. Where do we put it? We can grow trees, bottle carbon up in tanks, pump carbon into the ocean. But trees burn, tanks leak, and the ocean is already too acidic to hold any more carbon.
It seems like a bit of an inverse relationship emerges here. The more “useful” the carbon is, the more likely it will end up back in the air. Think about storing carbon to make synthetic gasoline. It’s very tempting to put that gas in a car and burn it up. It’s also easy to just burn it accidentally.
It would be better if the carbon was stored in a way that is useful of course! But none of that stuff weighs enough to remove a lot of carbon by itself. My personal carbon footprint is about 30 tons per year, and the weight of everything I own (car, furniture, stuff) is about 2 tons. If I built a house out of pure carbon, that’s about 20 tons, but I wouldn’t do that ever year.
Gigaton scale carbon removal seems to come down to storing a lot of carbon in a not-super-useful way.
Why Underground Storage Could Be the Gold Standard
- Permanence: When carbon is stored in rock, it stays there permanently. It’s expensive, it’s inconvenient, it’s fairly useless but at the end of the day it stays there.
- Low Maintenance Costs: Low, basically need to monitor above the site to see what amount of carbon is leaking out, if any. But there’s no need to count trees or take soil measurements every year.
Monitoring and verification is needed, certainly on the way in.
The biggest question seems to be “is this big enough?”. Are there enough basalt quarries to store gigatons of carbon from the air?
Given all this, I’m excited to see more experiments in underground storage pop up. Mines, basalt quarries, other types of rocks, different ways to capture carbon from the air.
