So the ELI5 is they burn crop waste, harvest the heat and bury the carbon-rich ash. This process is called BECCS. (Not totally right - see 'pkrein’s comment below.)
The upper bound on capture is pretty good! Almost 70% of yearly CO2 emissions.
> Intergovernmental Panel on Climate Change (IPCC), suggests a potential range of negative emissions from BECCS of 0 to 22 gigatonnes per year
[1]
> Human activities emit over 30 billion tons of CO2 (9 billion tons of fossil carbon) per year
[2]
The upper bound on capture is pretty good! Almost 70% of yearly CO2 emissions.
> Intergovernmental Panel on Climate Change (IPCC), suggests a potential range of negative emissions from BECCS of 0 to 22 gigatonnes per year [1]
> Human activities emit over 30 billion tons of CO2 (9 billion tons of fossil carbon) per year [2]
1 - https://en.m.wikipedia.org/wiki/Bioenergy_with_carbon_captur...
2 - https://en.m.wikipedia.org/wiki/Carbon_dioxide