Hacker News Reader

Comment by Scalene2 | Hacker News Reader

Why isn't carbon capture just: Take the fastest growing plant, grow as much as possible, turn it to charcoal or similar substance and bury it?

View on HN

This is one of the potential paths (look up BECCS/bioenergy with carbon capture and sequestration). Basically, grow something that grows very quickly (I think switchgrass is usually discussed), burn it for energy, and put something to capture carbon from the flue gas in the exhaust pipe, then sequester it.

But it has tradeoffs. It costs money, and compared to eg direct air capture, it uses land that would’ve otherwise gone to growing food or something else, so a not-insignificant opportunity cost.

And we’re not even doing carbon capture on coal plant flue gas, because there’s just no incentive.

If we rolled out serious carbon taxes, this would become more feasible in addition to putting capture on existing plants.

If you’re interested, I highly recommend the AirMiners course, it gives a good overview/survey of the literature. The tldr is that we’re going to need a cocktail of all sorts of these technologies to hit anywhere near our targets, in addition to getting to net zero. We need to be pushing for a carbon tax politically, hard, to make this economically viable to do at scale. People need to become single-issue voters on this, and let politicians know that they are.

Good primer on carbon tax with dividend and border adjustment: https://clcouncil.org/economists-statement/

Carbon tax in the west doesn't matter when china and India keep pumping out CO2.

I agree that carbon tax would be good, but unless it's a worldwide implementation it just won't have the desired effect - all it will achieve is disadvantage those who implement it relative to those who don't.

Fun fact: you don't have to bury it, you just have to not burn or decompose it. Hence why wood used in architecture functions as a carbon sink. [0]

[0] https://en.wikipedia.org/wiki/Carbon_sink#Artificial_carbon_...

If you just keep it alive, it occupies land. If you kill it, it will decompose. Hence the burying, right? Or am I missing something?

Wood decays when there is sufficient air and moisture. Wood used for construction is dried before being used, and unless there's a leak / excessive humidity, should be able to last a very long time without substantive decay. Wood in stuff like furniture is also often sealed with a specific wax/oil layer to keep out moisture, further preventing rot.

Theoretically it will decompose someday, but at the point where we have significantly less buildings I assume either other bad things have made this less of a concern, or we'll be advanced enough to recapture that carbon in other ways.

...but yes, if you're willing to "waste" the resources, just thoroughly burying wood away from air should also work.

This took place over ~800,000 years, and a lot of this is theory, but the Azolla event is an interesting parallel. Basically, you had a fast growing fern that was growing in an arctic basin. When they died, they sank to the bottom where conditions were anoxic, so they didn’t decompose and release carbon back into the atmosphere. Azolla was INSANELY good at sucking up CO2 (to the point that over those ~1 million years it might have reduced the CO2 in the atmosphere enough to end the last hothouse period).

I think the issue is that the scale of the problem is so big. This was close to the best case scenario for this kind of sequestration and it still operated on the scale of hundreds of thousands of years. It’s definitely something worth looking into (and I’m pretty sure people are, haven’t kept as up to speed as I’d like though), but we can’t expect it to save us on its own.

https://en.wikipedia.org/wiki/Azolla_event

Should be genetically engineering plants to optimize carbon capture too.

Great, let’s create the ultimate invasive species

Pretty sure what y'all are talking about already exists and it's called running bamboo. Grows aggressively fast, spreads quickly, and pretty successfully invasive.

It doesn't have to be engineered for aggressive growth to be engineered for greater carbon capture.

Aren’t growth and carbon capture practically the same thing?

Aggressive growth doesn't have to mean aggressive reproduction, it could mean fast growing giant redwoods being farmed in different climates.

Thanks for being clearer than I was.

If Monsanto could invent terminator seeds for their products I don't see why the same couldn't be done for trees specializing in carbon capture.

Yes, the best way out of human hubris is more human hubris!

Genetically modifying plants has saved millions, if not billions of people (https://allthatsinteresting.com/norman-borlaug-green-revolut...). Decrying it as an inherently foolish practice is silly.

Humans have been modifying wild plants to work better for us and worse for themselves since before written history.

Grow it where? You'd need to cover significant land mass, where food is being grown.

Reply on news.ycombinator.com