Comment by godelski | Hacker News Reader

Comment by godelski | Hacker News Reader

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To your sequestration comment.

No one is saying don't plant trees. Fuck yeah, plant all the trees! But that won't wont be enough. Sequestration will get better, but one of the big things it helps with is locality. CO2 isn't homogenously spread across the globe. It also doesn't spread very well. Concentrations vary drastically over the year and so do plants' ability to capture carbon. Carbon can build up in certain regions. Worse, it can pool where we can't grow trees [0]. Places where we can't get enough water to introduce new populations of trees (without significant carbon costs, defeating the purpose. Also the local ecosystem) Cities. The Arctic. The ocean. I'm all for planting trees (even beyond CO2, I just feel better around trees) but people need to stop making the trees vs sequestration argument. It's trees + sequestration (air and ocean) + promoting corral development + more. (This same argument applies to a lot of things, especially in climate. It's not a "this vs that" argument, it's "this PLUS that".

[0] https://youtu.be/x1SgmFa0r04

Sequestration is also good for catching carbon at potential emission sources; it's easier to grab CO2 out of the atmosphere at the point where you're burning methane than to let it out in the atmosphere and then try to catch it again.

(Or, in some interesting experiments, even before emission; there's work on splitting methane from natural gas into carbon and hydrogen and just burning the hydrogen. Gets you something like 66% of the energy of burning the methane completely, and with no CO2 emissions.)

Re: your second point, splitting methane into H2 and CO2 is not something that's being investigated at lab scale, it's how 95% of global hydrogen production today is done. We're talking close to a trillion cubic meters per year from steam methane reforming.

It's just that most of the time, resulting CO2 is just released instead of being stored. But that is changing, fast.

I was specifically referring to pyrolysis, where unlike steam reforming no oxygen is introduced and so the carbon comes out as solid graphite. Scaling the process, and running it in a continuous-operation reactor, is still an area of active engineering work (see e.g. https://pdfs.semanticscholar.org/d36a/ff0a2db0f99a92c2debd5b...), mostly focused on designing the physical system so that the solid carbon comes out nicely during the reaction instead of gunking up the works.

What are the benefits of pyrolysis versus steam methane reforming (SMR)? My immediate thought would be that you leave energy on the table, and that storage at scale is harder when the end result is graphite. Moreover, SMR is proven technology at very large scale.

One advantage is that it produces high-purity graphite, which is a moderately expensive commodity, used for electronics manufacturing (especially power components in batteries), structural carbon composites, and machine lubricants.

The percentage of carbon captured is also damn near 100% - quite a bit better than gaseous carbon capture techniques I've heard of.

You do leave quite a lot of energy on the table (losing somewhere between 30% and 50%), so this is a technology that is only economically viable with high emissions pricing. But that seems like the way Europe is going anyway.

And yes, SMR is the proven and clearly superior technology right now; I'd call this TRL 4/5 right now. But with another decade of development?

Aha, so it's targeting "CCU". Then OK, I can maybe see there is a point initially, but not at anything near the scale we need.

Global graphite production from mining is at 1 megatonne/year, while synthetic is a few hundred kilotonnes/year. We need CCS to operate at tens of gigatonnes per year, that's four orders of magnitude beyond all the graphite the world needs.

This is the problem with anything CCU - there just aren't viable options with consumption at the gigatonne scale.

I'd imagine extra graphite is pretty easy to store, though?

We could put it down in empty mine shafts... or build entire mountain tops out of it!

At the gigatonne scale, nothing is easy to store. Fill the entire Hoover dam with graphite, and you've stored 6 gigatonnes. We need to store tens of gigatonnes per year for a hundred years.

That’s a cool video. However the variation looks to be only about 2% from highest to lowest.

Trees will actually do the trick. I looked for an international business that would plant a 1000 trees for me which would offset my entire carbon footprint for my entire life. Didn't find anything except a local one in Iceland [1] in Icelandic only (good luck with Google Translate).

I can offset my footprint for 800$/year and I think it's going to be my New Years resolution. No more carbon from me.

Finding land and planning trees for it should be a global business. There are a lot of people like me with disposable income that would invest in something like that.

[1] https://kolvidur.is

Please also include a resolution to reduce your carbon emissions.

Remember that planting trees only work if you have the guarantee that in the future these trees will not be burned. Also, some natural decomposition also emits CO2

Planting trees can delay/slow down climate change. What happens in a decade when planting trees does not scale anymore and we've kept increasing our emissions in the same time?

I am about 50 years old. Planting trees scales for at least 50 years. Something on the order of 1000 trees will offset the entire footprint of a upper-middle class non-jetsetter (eats meat, travels 2-4 times per year, car, modest house).

There are a lot of technology promises on the horizon that will hopefully solve the next inflection point, but that's not my climate crisis, it will be the next generation. Hopefully by then the human race will have developed fusion or other energy technologies.

I’m no biologist but coral seems incredibly f*ed whenever I hear about it. Is there any chance of us actually saving coral?

There's a crash plan to save species of dying coral and another plan to develop/disperse heat-/acid-resistant species.

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