MIT engineers make converting CO2 into useful products more practical

The article annoyingly failed to close the loop from the $1,000/ton figure at the top and do the math on the economic efficiency potential of this approach. How much electricity is required to sequester each ton of CO2 using this method, assuming you can amortize the construction costs over some long duration? I assume the intended installation is on the exhaust of a fossil fuel burning facility, but is it possible to install this next to a solar field and generate ethylene from excess mid-day production? Large scale carbon sequestration is one of the major unsolved problems of the 21st century and we have to expect many false starts before the really viable technologies emerge.

One place to look for some math on the economic efficiencies is the blog of Terraform industries. Here's a start:

https://terraformindustries.wordpress.com/2024/04/01/terrafo...

> There is no hand waving about economies of scale or subsidies here, though we are eligible for the full IRA 45V green hydrogen tax credit, worth $3/kg-H2.

Their business model may have a slight problem.

Hum... No, the people studying new catalyzer shapes didn't do a through market research for a carbon sequestration plant.

They're saying that they don't need the green hydrogen tax credit. The tax credit makes their product profitable sooner, but as long as solar keeps following it's cost curve for a couple more years they'll be fine without it.

If they are sequestering by reducing (in the sense of donating electrons to) carbon, then that will, by thermodynamic necessity, require more energy input than oxidizing that carbon originally provided. Converting to ethylene, as they mention in the article, is such a process.

Yeah, figuring out a remotely accurate figure for that is at least as hard as the work done here, and requires pretty different sets of expertise

> Their business model may have a slight problem.

Oil is subsidized to a much higher amount by the US government

There are plenty of papers which look at precisely the economic and carbon tradeoffs of these sorts of processes. It all just depends on where you are. When you have a clean grid and a cheap grid, these methods become pretty feasible.

Take a look at De Luna et al, Science 364 2019 [1]

[1] https://www.science.org/doi/10.1126/science.aav3506

Yeah, but that subsidy is not likely to disappear in 2 months.

Subsidized in what way? I've heard many dubious things in the UK / EU called "fossil fuel subsidies" when it's mostly generic things like electricity having a lower VAT rate than the usual 20% (or whatever) on most consumer goods. This is the sort of thing that gets called a fossil fuel subsidy. I think a lot of these things are grasping at straws.

The top subsidy of fuels that emit carbon emissions is the externalities experienced by future generations. Not really measured in numbers, it will just be a change in quality of life.

That is an extremely interesting and potent way of phrasing it - thank you!