Climate Remediation Engineering - CO2 Removal Approaches

There have been many approaches to CO2 removal proposed over the
years, but very few attempt to estimate the dollar cost per ton of CO2
removed have been published. Here is a recent proposal that does
estimate costs:

Beerling, D.J., Kantzas, E.P., Lomas, M.R. et al. Potential for
large-scale CO2 removal via enhanced rock weathering with croplands.
Nature 583, 242–248 (2020).
<https://doi.org/10.1038/s41586-020-2448-9>

.<https://www.nature.com/articles/s41586-020-2448-9>

Extracted from the Abstract:  "Enhanced silicate rock weathering
(ERW), deployable with croplands, has potential use for atmospheric
carbon dioxide (CO2) removal (CDR), which is now necessary to mitigate
anthropogenic climate change. ... China, India, the USA and Brazil
have great potential to help achieve average global CDR goals of 0.5
to 2 gigatonnes of carbon dioxide (CO2) per year with extraction costs
of approximately US $80–180 per tonne of CO2. These goals and costs
are robust, regardless of future energy policies. Deployment within
existing croplands offers opportunities to align agriculture and
climate policy. ... "

That's a pretty wide cost range, so we will use the geometric mean,
Sqrt[80*180]= 120 US dollars per metric ton of CO2 removed. 

Also note that this is an academic analysis, and so is most likely
quite optimistic compared to a contractually-binding full engineering
cost estimate.  However, here is another datapoint reinforcing that
estimate:

"Carbon Capture Is Key to Companies’ Net Zero Pledges -- Some
carbon-dioxide removal techniques that companies rely on to improve
their environmental footprints are riskier than others", By Rochelle
Toplensky, March 17, 2021 6:09 am ET, The Wall Street Journal.

Relevant quote: "Project economics depend on the volume and purity of
CO2 and the distance to the carbon reservoir, but it is 'highly
likely' a facility can be economic at carbon prices of around $100 a
ton, says Syrie Crouch, vice president of CCS at Shell. "

.<https://www.wsj.com/articles/carbon-capture-is-key-to-companies-net-zero-pledges-11615975780>

The CDIAC tells us that one ppmv of CO2 in the Atmosphere weighs 7.816
metric gigatons, of which 2.133 gigatons is the elemental carbon
component, so 100ppmv of CO2 will weigh 781.6 gigatons.  Using
Beerling's estimate of US $120 per metric ton to remove CO2 from the
atmosphere, we find that the cost to remove 100ppmv of CO2 to be US
93.8 Trillion US dollars.  To return to pre-industrial CO2 levels
would cost twice that, or 188 Trillion US dollars.

For comparison the 2020 GDP of the entire world is 88 Trillion US
dollars. The GDP of the West is about 40 Trillion, or slightly less
than half the world GDP. 

Datapoint:  Over the five years of WW2, the US spent on average 27% of
their GDP, squeezing everything else out to the margins, and they are
probably still paying for it. 


Joe Gwinn