[_Microft]

Here's two questions for you which are not hard to answer but, frankly, I do not expect to read the answers here. Why? Because it would show how utterly wrong the suggestion of carbon sequestration for solving this problem was.

First: how much mass (i.e. kg or tons) of C0_2 is emitted per year?

Second: what is the total mass of concrete produced per year worldwide?

(This is only an exercise to give parent poster an idea of the scale btw)

[TeMPOraL]

Re your first question, quick googling suggests some 37 billion tons of CO₂ per year. So sure, that's a lot. But then again, not that lot.

Instead of asking questions, why don't you tell us why we couldn't possibly sequester that much carbon annually? How big is the divide between what we could do and what needs to be done?

(I must say the idea of sequestering carbon seems emotionally appealing to me because it turns the problem into something much more tangible. You're not going to get people to cut their CO₂ emissions enough to matter without pushing for a strong emission taxing (which I'm also a fan of). Lowering your living standards doesn't feel like it's accomplishing much vs. the pain involved. Sequestering CO₂ would turn the problem into a numbers game, "how many tons is our country pulling out of the atmosphere, and where do we throw the money to get that number up?".)

[jandrewrogers]

In principle, with extreme heroic effort, we could sequester 37 billion tons of CO2 per year, but we should be clear on just how extreme “extreme” is. Remember, every single part of the logistical supply chain would need to be scalable a million-fold the same way that the actual sequestration plant would need to be. There are two big practical engineering problems that have to be solved first, that have not been realistically addressed.

First, we would need to double global electricity generation to a first approximation. The laws of thermodynamics make this non-negotiable. Very few power generation technologies not based on fossil fuels can scale like that. Nuclear power plants, realistically, and thousands of them in very short order.

Second, the chemicals used in industrial sequestration produce hazardous byproducts on a scale similar to the CO2 being sequestered, byproducts like hydrochloric acid. Today, this is easy to handle because we produce truly trivial quantities of the chemicals required for sequestration. Not only is there no industrial capacity to produce the required chemicals, nor an obvious way to scale them, there is also no plan for disposing of the billions of tons of caustic chemicals that would be thrown off as a side-effect of their manufacture. It doesn’t do us any good to remove the CO2 from the atmosphere if we end up turning the planet into a superfund site. Nobody accounts for hazardous byproducts of the proposed technology supply chains, which will be produced on similar scales.

As I’ve noted previously, we can reduce this to a much simpler sub-problem that is easy to reason about: what would be required to produce enough potassium hydroxide to sequester 37 billion tons of CO2 per year? All the required facts and figures are public knowledge and relatively basic science. The amount of electricity required per ton is widely documented, as are the chemical inputs and byproducts. And then, once you’ve realized the extent to which that asymptotically approaches impossible, do the same kinds of calculations on the upstream supply chain for the inputs to that process, which is also public information. It falls apart very, very quickly.

[sokoloff]

It seems to me like we need to do both: tax carbon (ideally globally, but even if half the developed countries do it, it's huge) AND use that tax money to work on research and deployment of carbon sequestration or carbon to fuel conversion.

[TeMPOraL]

That's my current belief too.