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, 242û248 (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 $80û180 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 CompaniesÆ 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

--- SoupGate-Win32 v1.05
* Origin: fsxNet Usenet Gateway (21:1/5)

On 6/05/2025 3:04 am, Joe Gwinn wrote:

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.

This is fine as far as it goes, but nobody sane is relying on actively
removing CO2 from the atmosphere to reverse anthropogenic global warming.

The current strategy is to invest heavily in renewable energy sources -
wind turbines and solar panels - so that we can slow down the rate at
which we are burning fossil carbon as fuel (and dumping the CO2
generated into the atmosphere). The hope is that natural weathering can eventually take enough of it out to reverse the warming we have seen so far.

We are getting close to the point where the amount of CO2 being dumped
in the atmosphere is going to level off. We need to get to the point
where it is going down.

It took about twenty years of development to get the price of renewable
energy below the price you have to pay to dig up and refine fossil
carbon into a state where you can burn it to generate energy.

This work has changed our world, and one of the changes is that all the
people who invested heavily in making fossil carbon accessible are going
to be making progressively less money out of those investments

They pay for a lot of climate change denial propaganda which claims that
we haven't got there yet. Gullible twits like John Larkin and Cursitor
Doom are suckered by this.

Greed will eventually move us over to renewable energy sources, but it
is going to take a while. The hope is that anthropogenic global warming
won't get too bad before we get there.

Silicate rock weathering has always worked in the past - look at Paleocene-Eocene Thermal Maximum some 56 million years ago.

https://en.wikipedia.org/wiki/Paleocene%E2%80%93Eocene_Thermal_Maximum

The temperature took about 20,000 years to peak, and about 150.000 years
to get back down again. Grinding up lots of silicate rock should make
the recovery go faster, but - as you say - it will meaning grinding up
a lot of rock.

Stopping burning fossil carbon as fuel would be cheaper, but it means
changing society, and today's fat cats aren't happy about being put on a
diet.

--
Bill Sloman, Sydney

--- SoupGate-Win32 v1.05
* Origin: fsxNet Usenet Gateway (21:1/5)

On 6/05/2025 3:04 am, Joe Gwinn wrote:

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.

Just the fact that people are still burning coal for energy as a
business (at about 30% thermodynamic efficiency) is enough to tell you
that doing the exact opposite process is not going to be
thermodynamically and economically justifiable at the same time.
Otherwise we would put the two processes in the same box and have a
perpetual motion machine (and free money machine)!

If we value having the carbon in solid form rather than as gaseus CO2,
then before paying to convert the CO2 gas to coal, the first thing we
should do is to stop converting coal to CO2 gas. The second thing would
be to pay other people to also stop. It would be far cheaper than CO2
capture. The present purpose of CO2 capture is as a hand-waving excuse
for politicians to build new coal power stations and approve new coal mines.

--- SoupGate-Win32 v1.05
* Origin: fsxNet Usenet Gateway (21:1/5)

On 5/5/2025 5:33 PM, Chris Jones wrote:

On 6/05/2025 3:04 am, Joe Gwinn wrote:

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.

Just the fact that people are still burning coal for energy as a business (at about 30% thermodynamic efficiency) is enough to tell you that doing the exact
opposite process is not going to be thermodynamically and economically justifiable at the same time. Otherwise we would put the two processes in the same box and have a perpetual motion machine (and free money machine)!

If we value having the carbon in solid form rather than as gaseus CO2, then before paying to convert the CO2 gas to coal, the first thing we should do is to stop converting coal to CO2 gas. The second thing would be to pay other people to also stop. It would be far cheaper than CO2 capture. The present purpose of CO2 capture is as a hand-waving excuse for politicians to build new
coal power stations and approve new coal mines.

Well said.

--- SoupGate-Win32 v1.05
* Origin: fsxNet Usenet Gateway (21:1/5)