Re: [CDR] "The Carbon removal sector needs a new story"
Michael MacCracken
Dear Robert C--I fully agree with your diagnosis that SRM is essential and its cooling effect can't be met by enough of a phasing up of CDR in the time needed. Where I would differ with you, however, is that I think that in promoting SRM/SAI, it is essential to have an exit strategy that one can offer, even if it will take through the century or more. Mitigation is not adequate as an exit strategy from higher temperatures--its main role is to keep warming from getting even warmer. And because of increasing natural emissions of CO2 due to global warming, even net zero direct human emissions may not stop warming. So, what CDR has the potential to do is to build up to become a potential exit strategy from indefinite continuance perhaps the need for further and further strengthening of SRM/SAI and adaptation. As noted, I thus think that we have to include CDR is the long-term comprehensive strategy that we argue for. If CDR can be successful faster, all the better; if not so fast, then SAI/SRM and adaptation and their limits point even further to the need for faster mitigation.
Regards, Mike MacCracken, Ph.D.
Hi all
This thread suggests that the time has come to decouple CDR from climate change policy. Whether there is a market for CDR and how it might operate is totally irrelevant to policy intended to avoid a global warming (GW) induced societal collapse. Indeed, significant investment in a forlorn attempt to give it such a role, is likely to make matters worse. Here's why.
In what follows I ignore non-CO2 GHGs. Including them makes the story significantly more complicated and only serves to make the case more strongly. If the case can be made with sufficient force without them, it makes the argument considerably more accessible. The numbers shown below come from a modified version of FaIR v2.0.0.
GW is driven by the 1100GtCO2 that remains in the atmosphere from the 2800GtCO2 emitted since industrialisation. Holding GW to +1.5oC (without SRM) assumes returning COs concentration to 350ppm. Let's for the moment assume that that's a sufficient ambition.
Let's also assume, to keep things simple, that CO2 concentration peaks at 450ppm (e.g SSP2-4.5 amended slightly so that emissions subside to 10GtCO2yr-1 by 2120 and remain there indefinitely). This would require CDR totalling 3300Gt over the next 100 years which is heavily front-loaded if we want largely to eliminate the overshoot. If we're willing to accept overshoot peaking at +2.3sC in 2060 before slowly falling to +1.5oC by 2120, we could manage with slightly less than 3000GtCO2 of CDR over the coming century.
I'd welcome correction, but I consider CDR at that scale to be utterly implausible. Data from Carbon Dioxide Removal shows CDR from af- and re-forestation flatlining at around 2GtCO2yr-1 for at least the last 25 years, and CDR from novel methods still being insignificant at little more than 1MtCO2yr-1. The economic and environmental implications of safely capturing and permanently sequestering tens of gigatonnes of atmospheric CO2, an endeavour that would be larger than the current total worldwide extractive industries, render this implausible within any useful timescale. Some believe this could be done by ocean iron fertilisation, or some similar marine based process. There is currently no evidence to support this.
As an instrument of climate policy, CDR is so far from being able to make a worthwhile contribution that its inclusion in those policy considerations should be reconsidered. Indeed, it can be argued that any investment in anything other the the lowest hanging CDR fruit, detracts from devoting financial and other resources in those policies that might have some meaningful climate impact; namely reducing emissions by a range of measures and SRM.
That said, there is no reason not to encourage a market in CDR. If entrepreneurs see an opportunity to make money, good luck to them. Some CDR technologies also have major environmental benefits that should be promoted. But let's not kid ourselves that any of that will be doing much to avert a climate catastrophe.
If we now look at whether +1.5oC/350ppm is a sufficient ambition, and how much overshoot we think might be safe, the case against CDR becomes even more compelling. The impacts of the climate change that's already emerged from GW that has only just reached +1.5oC are now manifest. These changes will not stop if we hold GW at that level. For example, Arctic amplification will mean the continuing and hastening loss of land and sea ice above 60oN and this will have increasing effects on climate elsewhere, in particular because there is every reason to suppose that AMOC will continue to slow, maybe even to a standstill. There seems a compelling risk based case to reduce warming to much lower than +1.5oC, maybe to +1oC or even below. +1oC implies CO2 of around 300ppm. Delivering that makes our plausible CDR look even more pointless. The problem here is twofold. Not only would CDR have no chance of restoring atmospheric CO2 to a safe level, but the overshoot while we were trying would be extreme and extended. Indeed, the likelihood is that the accumulated GW would soon trigger one or more of the cascading tipping points much explored by Lenton and his team.
Any sane risk focussed climate policy must now regard time as being of the essence. Like it or not that means SRM must now be regarded as necessary and financial and other resources must be invested in the R&D to derisk it to the extent possible. This has become a top policy priority.
In summary, let the entrepreneurs and environmentalists play with CDR to their hearts' content, but those with a serious interest in securing a safe climate future for humanity and the rest of life with whom we share the planet, need to focus on cooling. That means SRM because it is radiatively efficient. But retiring fossil fuels remains vital because they are the source of the problem. Sadly, their retirement can no longer be the only policy option (having discounted CDR in this regard) because CO2 is radiatively extremely inefficient and we have allowed the amount of atmopsheric CO2 to accumulate to such an extent that to make any appreciable temperature difference, truly immense amounts of it have to be removed from the atmosphere and there is currently no plausible way of doing that at the scale and speed required.
There is no so-called 'moral hazard' here because both SRM and the retirement of fossil fuels are equally important and mutually supporting; neither works without the other.
Regards
Dr Robert Chris
On 06/02/2026 23:51, Greg Rau wrote:
----Thanks Robert. You say we do need cheap, effective CDR to remove legacy CO2 "but having someone to pay for it is relatively far away". I find that illogical. We are suffering right now from excess legacy CO2 that can only be reduced (faster than on geologic time scales) via pro-active CDR, not by reducing emissions. This will only get worse by the time we ever get to zero emissions. Why shouldn't CDR have at least equal footing (in terms of investment and incentives) with emissions reduction rather than being simply view as offsetting hard to abate emissions?
This plays in to my second comment "On the other hand if emissions reduction is wildly successful, won't this present a moral hazard to CDR?" Think about it, if all people want is zero emissions and this achieved by actually reducing emissions, then by their reasoning, why do we need CDR? This again fails to appreciate that by then we may have 2000 Gts of legacy CO2 up there that will impact climate and ocean chemistry for many hundreds to thousands of years*. This can ony be remedied by CDR and SRM (the latter, just addressing the climate part (in theory)).
Bottom line, there are both near-term and long-term, multi $T risks/reasons to elevate CDR beyond just being an appendage to emissions reduction. Why is this being ignored in policy/investment circles? Isn't this a "new story" that CDR needs?Regards,Greg
On Thursday, February 5, 2026 at 06:15:59 AM PST, Robert Höglund <robert.d...@gmail.com> wrote:
Thanks for the discussion Ron and Greg!
Ron, my comment on CDR on the hype curve is for carbon removal as an aggregated topic (which is how most people talk about it), not technology per technology. If you break out biochar I agree it is growing and not on a downwards journey.
Figure 3 is not mine, but comes from the Climate change project, it only includes mitigation costs of low carbon inputs that companies have reported. CDR is not a part of it.
Greg, one of the big reasons for why we need to build CDR as a ready tool with low costs and MRV etc worked out, is so that it is ready to remove all those legacy emissions. But having someone to pay for it is relatively far away.
Not sure what you meant with this comment. "GR - One the other hand if emissions reduction is wildly successful, won't this present a moral hazard to CDR?"
best regards
Roberttorsdag 5 februari 2026 kl. 08:06:04 UTC+1 skrev rongre...@comcast.net:
Greg and list:I've been preparing a comment for the "biochar.io" community on this same report, so will just give a few comments here first.1. I see no evidence here that he is giving a report here that includes biochar - a topic he knows well His Figure 1 with a trough may now be happening with BECCS and DACCS, but certainly not biochar. Doubling times for biochar are still less than two years - no negative slope years at all.2. His Figure 2 (with about 10 boxes) doesn't include a box for agriculture, forestry or municipal wastes. Ag is the world's largest industry by some measures.3. In his Figure 3, I would draw the price range for biochar much as he has drawn top-most for "steel". Note the left -most number on the abscissa should be 1, not 0.I won't comment on your two quotes below - except to repeat that I disagree with a lot if he is including biochar in this note - which doesn't seem possible.I have good respect for everything else I have seen from Hoglund on biochar (now the leading CDR technology by some measures).Thanks for your alert on this out-of-character report.RonOn 02/04/2026 9:35 PM PST Greg Rau <gh...@sbcglobal.net> wrote:from Robert Hoglund's article (below):"Gigatonne scale CDR is conditional on success on emission reductions. That means the primary political fight is for stronger climate policy, not for scaling carbon removal in isolation."GR - One the other hand if emissions reduction is wildly successful, won't this present a moral hazard to CDR?"Finally, the biggest use case for CDR may be to remove legacy emissions to bring temperatures back down, but who will want to pay for that and if so when, are even bigger and more uncertain questions."GR - This truly is the biggest case for CDR, but no one is interested? They will be when they find out how long Earth inhabitants will suffer waiting for natural CDR to return CO2 and climate to "normal" levels on geologic time scales. But then there's always SRM in the meantime?
The Carbon removal sector needs a new story
From speed and scale to prove and learn
I think most people in CDR feel that a phase shift has happened. The old story doesn’t hold but no new clear narrative has emerged of what role CDR really will take in the real world in the decades to come. Voluntary demand is likely to continue to increase but not explode, compliance demand is slow and may be much smaller than people expect even in the long-run. To me, the new story is more prove and learn than speed and scale.
First, what is likely to happen? Starting with the next ten years
The number of companies buying durable CDR will continue to increase, but there is no reason to think it will explode. The ones buying will primarily be seeking to meet targets. Like operational net zero targets by 2030 for their Scope 1,2 and business travel. Something that would make more companies buy CDR for such operational net zero claims is validation for that practice from SBTi, ISO etc. Regardless, I expect voluntary demand for durable CDR to result in low tens of millions of tonnes delivered per year in the mid 2030s. A possible scenario is that total contracted tonnes temporarily peaked in 2025 or 2026 because of Microsoft’s forward buying spree, and that it will take a while before we reach 30 million tonnes contracted in one year again.
For compliance, the only real driver for durable carbon removal in the medium term is inclusion into the UK and EU ETS. But simple integration of CDR into UK & EU ETS would likely not lead to much, if any CDR demand in the next ten years since ETS allowance prices are lower than even cheap CDR levels. Any CDR included in that timeframe would need to be paid for by governments through contracts for difference or similar. Such government support will enable single millions of tonnes per year, maybe more, in the early 2030s but I think voluntary demand will continue to dominate durable CDR delivered for the next 5-10 years.
Now, in my book, tens of millions of tonnes delivered across multiple methods is an incredible win. That means we proved that CDR works outside of small experiments and learn a lot about how to bring down costs and about which methods have the highest potential to scale to much higher volumes. This has to me always been the primary objective of the early CDR ecosystem.
Of course it is a brutal hype adjustment as the narrative that many painted for CDR was 6-10 gigatonne by 2050 and a linear growth towards that. CDR has been traveling downwards on the hype curve for at least a year and a half. Consequently, I think venture capital investments will continue to fall, this phase favors patient capital. Maybe we’ll hit the trough of disillusionment bottom this year, readjusting expectations, and start aiming for the plateau of productivity.
My estimate for where CDR is on the Gartner hype cycle
Post 2035. What does the plateau of productivity look like?
CDR is probably the cheapest mitigation option for something like 2-5 Gt carbon dioxide per year. It’s hard to say exactly as technology development progresses and local conditions vary.
My long run macro estimate of where CDR is the cheapest mitigation option for CO₂ emissions.
But, that number only matters if the whole world is trying hard to get to net zero, and treats CDR as a valid mitigation option. Currently neither is really true.
Compliance is usually expected to be the biggest driver in the longer run, but only the EU and UK have live net zero plans that would force all CO₂ emissions down to zero. If that happened, CDR might be the cheapest option for 100-200 Mt per year of emissions in those two jurisdictions, demand that would need to be met in the 2040s. (However for aviation and shipping which are part of that number, fuel switch is currently mandated in the EU with no real role for CDR).
If the rest of the world does not follow Europe, I think it is quite likely that the EU does not push full decarbonization for heavy industry. This is driven by a need to keep industrial capacity in the union, not the least to have an industrial base in case war production needs to be ramped up. The cost for both CCS and CDR is not likely going to be able to be pushed to heavy industry. If Europe maintains net zero plans it will likely need to spread the cost of mitigating heavy industry, either through the state directly paying, or through demand side legislation making customers pay, combined with a granular and very heavily enforced CBAM.If the rest of the world is serious about reaching net zero there will be a lot more CDR demand. US ambitious individual states are things to look at for example. But there is no scenario where we build out gigatonnes of CDR if global emissions are not rapidly falling. Gigatonne scale CDR is conditional on success on emission reductions. That means the primary political fight is for stronger climate policy, not for scaling carbon removal in isolation.In the light of this, it is actually possible that voluntary demand could exceed compliance demand even in the medium to long run. CDR is cheaper than many substitution options companies have. In a couple of decades I think it is possible (but not necessarily likely) with hundreds of millions of tonnes in voluntary corporate annual demand if the narrative shifts sharply and companies feel buying CDR is expected from them. Almost all companies can afford to buy durable CDR for a subset of their emissions, and some can afford it for all. But in no case I see voluntary demand reaching gigatonnes per year.CDR is cheaper than many substitution options companies have today. From Climate Change Project companies’ mitigation cost estimates for low carbon inputs.
Finally, the biggest use case for CDR may be to remove legacy emissions to bring temperatures back down, but who will want to pay for that and if so when, are even bigger and more uncertain questions.
What is the new story then?
To me, the CDR sector has two roles. Building, proving and improving a toolkit that the world can use for gigatonne level of removals when it gets serious about reaching net zero. And, providing a way for companies, ambitious regions and countries and individuals to take responsibility for their emissions today while making credible claims. The story is not rapid scale, but proving, learning, and earning trust.If you are working on carbon removal, nothing in this text should make you put in less effort. We need to keep developing CDR, test new methods, lower costs, find out what works and build demand so that we have the best tools available for global net zero and large scale legacy emission removal. But we need to do it with realistic expectations. The road ahead is narrow.
© 2026 Robert Höglund
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robert...@gmail.com
Hi Mike
I've no problem with that. I just presented one scenario but there are obviously many alternatives.
In the scenario I used below, emissions reduced to 10GtCO2yr-1 by 2120 and remained there. You then have the question about what you do with the residual emissions. Clearly one option is to reduce them to zero but, equally, you could offset them with CDR. A lot depends on the level of residual emissions and the extent to which our successors have been successful in finding alternative energy sources. We can't know that today, so our policy decisions have to be open in that regard. Our main obligation is to keep humanity in the game so that future decision makers have the luxury of getting to screw up for themselves. Whether they would want to get to net negative emissions is a question we can leave to them but no amount of CDR that we can plausibly expect to do in the near future is likely to have much impact on their CDR decision in the future.
My argument today is that the radiative inefficiency of CO2 is such that we're better off to focus our GHG reducing efforts on retiring fossil fuels simply because it has to make more economic sense to invest in technologies to and behaviour changes that reduce energy intensity (MJ/$GDP) and/or carbon intensity (kgCO2/MJ), than to launch a gargantuan new industrial infrastructure with all its additional costs.
In the boundary case, in which we retire all fossil fuels in 2026 (obviously only a thought experiment!), ppm gradually subsides to 350 by 2300 but warming is held steady at +1.5oC having peaked briefly at +1.6oC.
So, the model suggests that the amount of CDR that might be needed is dependent on the rate at which emissions are retired, the rate and extent to which SRM is called and the amount of warming and overshoot we're prepared to tolerate. Nevertheless, as a policy choice, retiring fossil fuels should always take precedence over CDR because it just makes no sense, as anything other than an expedient short term strategy, to emit the stuff only to then have to recapture and sequester it.
But the central point I'm making is the one you endorse, that without SRM the whole house of cards collapses. And the reason, that I think is not widely appreciated, is the incredibly low radiative inefficiency of CO2. For those reading this that are not aware of this, the detail is uncontroversial and is covered in several IPCC ARs including AR6. The radiative efficiency of CO2 is 1.33E10-5 Wm-2kg-1 (it's not a fixed amount and changes with the ppm). What that means in lay terms is that to generate a forcing (whether warming or cooling) of 1 Wm-2, you have to shift about 600GtCO2, that's equivalent to 15 years' global emissions at current rates. In crude terms, 1Wm-2 will generate an equilibrium temperature difference of about 1oC (this is critically dependent on Equilibrium Climate Sensitivity but we'll not go there right now!). So from a purely practical engineering perspective, to make a significant change in surface temperature you have to reduce atmospheric CO2 by a vast amount. And as if that weren’t bad enough, because of a whole load of complex interchanges within the climate system, to reduce atmospheric CO2 by any amount, you have to remove almost twice that amount from the atmosphere. That's why cooling by trying to reduce atmospheric CO2 takes so long and is so expensive.
Robert
GRETCHEN & RON LARSON
- "DACCS: Up to $180 per metric ton of CO₂ for dedicated geologic sequestration.
- BECCS: Up to $85 per metric ton of CO₂ for dedicated geologic sequestration (classified under industrial/power source capture). "
Drop another third if CCS becomes CCUS.
On 02/07/2026 2:33 PM PST Robert Höglund <robert.d...@gmail.com> wrote:Yes its good 45Q remainsIt makes DAC and BECCS in the US be a bit more competitive with biochar, but you still need voluntary buyers that found a reason to buy.Robert
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robert...@gmail.com
Hi Ron
I'm delighted to have seen your PS abut my numbers being way out of date. That's hardly surprising because they're now much more than a decade old.
Would it be too much to ask if you could provide current values for the many variables so that the computation can be brought up to date. I'm assuming that you didn't have a problem with the methodology I adopted, but of you did, perhaps it would be best to deal with that first.
Robert
Michael MacCracken
Hi Robert--Agreed, with one comment. One reason that CO2 is a relatively ineffective GHG, at least compared to methane and the chlorinated compounds is that its concentration is much higher than for the other gases and so the central parts of the bands are already well absorbed, etc. This was actually a criticism back for Arrhenius to explain with his multi-layered model and a decreasing temperature with altitude. So, CO2 is of order 525 ppm and methane is 2 ppm and the hydrofluorocarbons are another factor of 100 or more less. So, what really matters is the influence of the existing concentration and so the relative percentage increase in the concentration.
Now, as to a comparison with water vapor, which, overall, has the strongest GH effect, there is so much more water vapor in the lower atmosphere, I'm not sure how one would make the relative effectiveness calculation. With water vapor concentration going up 7% per degree and the water vapor feedback contributing to say, half of the climate sensitivity (which we can say is 3 C), that would have a 21% increase in water vapor leading to a 1.5 C warming, and a CO2 doubling contributing, without the water vapor and other feedbacks, to maybe 1 C of warming (or does the CO2 doubling get credit for all the 3 C?). Not quite clear how to say which molecule is most or least effective.
Best, Mike
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Robert Chris
Hi Ron
Reflecting overnight on my message below, I am intrigued to know the extent to which my out-of-date computation deviates from one that is in-date. I suspect that several of the variables will not have changed materially (e.g. carbon content of biomass, carbon yield per hectare, biomass density, carbon content of biochar, available land, and size of a TEU). That just leaves the production capacity of a biochar plant and the number of trips made each year by each container.
It's not very helpful merely to comment that the schedule is 'out-of-date' without explaining the extent to which it is now misleading. Numbers please. In the absence of credible numbers that show how the biochar process has radically altered in the last decade or so, one must assume that it hasn't.
As a foreigner, I don't understand quite what 45Q is or how it works. All I know is that it's some kind of tax break to encourage investment in certain activities rather than others. However effective it might be in fomenting biochar growth in the US, I'd be interested to understand how that might have any global climate change significance.
Just to be clear, if there's money to be made and local environmental benefits to be gained from ramping up biochar production, I'm all for it. In the absence of compelling new information, I just object to it being presented as part of a meaningful response to global climate change. It simply isn't sufficiently scalable.
Robert
GRETCHEN & RON LARSON
On 02/08/2026 5:07 AM PST Robert Chris <robert...@gmail.com> wrote:Hi Ron
Reflecting overnight on my message below, I am intrigued to know the extent to which my out-of-date computation deviates from one that is in-date. I suspect that several of the variables will not have changed materially (e.g. carbon content of biomass, carbon yield per hectare, biomass density, carbon content of biochar, available land, and size of a TEU). That just leaves the production capacity of a biochar plant and the number of trips made each year by each container.
It's not very helpful merely to comment that the schedule is 'out-of-date' without explaining the extent to which it is now misleading. Numbers please. In the absence of credible numbers that show how the biochar process has radically altered in the last decade or so, one must assume that it hasn't.
As a foreigner, I don't understand quite what 45Q is or how it works. All I know is that it's some kind of tax break to encourage investment in certain activities rather than others. However effective it might be in fomenting biochar growth in the US, I'd be interested to understand how that might have any global climate change significance.
Just to be clear, if there's money to be made and local environmental benefits to be gained from ramping up biochar production, I'm all for it. In the absence of compelling new information, I just object to it being presented as part of a meaningful response to global climate change. It simply isn't sufficiently scalable.
RegardsRobert
On 08/02/2026 00:32, robert...@gmail.com wrote:Hi Ron
I'm delighted to have seen your PS abut my numbers being way out of date. That's hardly surprising because they're now much more than a decade old.
Would it be too much to ask if you could provide current values for the many variables so that the computation can be brought up to date. I'm assuming that you didn't have a problem with the methodology I adopted, but of you did, perhaps it would be best to deal with that first.
RegardsRobert
On 08/02/2026 00:13, GRETCHEN & RON LARSON wrote:Hi again Robert Hoglund and others:The current allowable "payment" for DACCS and BECCS sequestration was given to me just now by my Google AI helper:
- "DACCS: Up to $180 per metric ton of CO₂ for dedicated geologic sequestration.
- BECCS: Up to $85 per metric ton of CO₂ for dedicated geologic sequestration (classified under industrial/power source capture). "
Drop another third if CCS becomes CCUS.If these two CDR options are in trouble, my guess is that the low 45Q support levels are the cause of their trouble - not a future solution.Biochar tried to get into 45Q (at any level) - but has been excluded. Maybe why biochar is succeeding so well?Ronps Robert Chris' implementation numbers for biochar below are way out of date.
Bruce Melton -- Austin, Texas
Robert,
IRS Section 45Q does not require voluntary buyers.
This IRS incentive is 1) a tax incentive, and 2) a direct cash pay for carbon oxides sequestered permanently. There are over 100, 1 million ton per year units (+/-) committed right now under 45Q. The first to begin operation is Oxy's Stratos in the Permian, Phase 1 at 550 Mt per year, operational 1st quarter 2026. There is no cash pay cap for 45Q, either individually or cumulatively. using union labor, the pay is $85 ton for enhanced oil recovery (EOR) and $180 ton for direct sequestration or utilization, where photosynthesis processes such as algae are now allowed (no forests), and EOR is easily carbon negative by leaving more CO2 in the ground after the recovery process is complete, and with $85 ton pay, and mining, and or refining Co2 from natural gas/ammonia costs $40 to $60 ton, there will be lots of CO2 pumped into played out EOR wells.
Considering this, what is your opinion of this massive cash giveaway as a "new story," that does what emissions reductions cannot do: restore our climate before the tipping point of no return for activated tipping systems whose collapses become irreversible by mid-century.
Steep trails,
B
Oxy's Stratos, Summer 2025
Director, Climate Change Now Initiative, 501c3
President, Melton Engineering Services Austin
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Yes its good 45Q remainsIt makes DAC and BECCS in the US be a bit more competitive with biochar, but you still need voluntary buyers that found a reason to buy.
Robert
On Sat, 7 Feb 2026, 23:25 'Michael MacCracken' via Carbon Dioxide Removal, <CarbonDiox...@googlegroups.com> wrote:
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Bruce Melton -- Austin, Texas
There are no "low 45Q support levels." IRS Section 45Q Credit for Carbon Oxide Sequestration is not a voluntary carbon credit program. It is a tax incentive and or direct cash pay for permanent sequestration, with no pay cap either individually or cumulatively.
Biochar's inclusion in 45Q has been a hot topic for a decade. It is now proposed to be included in Section 45Q in the Fix Our Forests Act, which is very unfortunate as this act puts our nations forests at high risk of human-caused degradation, with much greater human intervention allowed in forests and roadless areas than under current rules - the former being critical, the later being unconscionable. The Fix Our Forest Act has passed the House and is in committee in the Senate. See here...
Steep trails,
B
Director, Climate Change Now Initiative, 501c3
President, Melton Engineering Services Austin
8103 Kirkham Drive
Austin, Texas 78736
(512)799-7998
ClimateDiscovery.org
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MeltonEngineering.com
Face...@Bruce.Melton.395
Inst...@Bruce.C.Melton
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Bruce Melton -- Austin, Texas
The cost of removal is nowhere near $400 a ton. This myth of exorbitant costs of air capture is widespread and based on authoritative publishing that is inaccurate based on numerous rebuttals that state they used inappropriate process assumptions and used enthalpy backwards in their calculations.
IPCC AR 6 doesn't go as high as $400 ton with
their $84 to $386 per
ton range, where they cite the National Academies work on the
topic. These costs are also based on processes
currently in industrialization where the lowest costs are the
latest findings.
The National Academies Negative Emissions Report in 2019 - https://nap.nationalacademies.org/read/25259/chapter/1#ii
IPCC WGIII, Chapter 12, page 12-43, based on National
Academies of Sciences Negative Emissions Report 2018.
https://report.ipcc.ch/ar6wg3/pdf/IPCC_AR6_WGIII_FinalDraft_Chapter12.pdf
Oxy's Stratos in the Permian Basin is based on
Keith's $94 to $232 per ton, where this range is biased high
because of Keith's assumptions described below. The actual cost of
Keith 2018 when considering renewable generated energy is $45 ton
without process enhancements:
Keith 2018 costs of $94 to $232 per ton CO2 removal -
• The $94 to $232 per ton range reflects the low and high
energy costs of the cheapest fracked gas at the time of $0.03 kWh
to $0.06 kWh.
• Keith includes a 10% carbon penalty for the natural gas
energy, in other words, his paper says it takes 10 percent more
process to remove the carbon emitted from burning the natural gas
to create the energy to run the process.
• Latest wind and solar costs, utility scale are now at $0.01
kWh.
• Keith includes 8% profit and a 7.5 to 12.5 percent capitol
recovery factor.
• The process has a levelized efficiency of 90 percent
considering upstream and fugitive emissions in the process and
sequestration transportation and injection.
• 87 percent of total costs are energy related.
• 60 percent of energy costs mus t be from flame oxidation with
natural gas, but 40 percent can be from electricity at the $0.01
onsite municipal-scale generation, totaling about $45 a ton.
Keith et al., A Process for Capturing CO2 from the Atmosphere,
Joule, August 15, 2018.
https://www.sciencedirect.com/science/article/pii/S2542435118302253
Hansen's assumption that air capture is infeasible because of costs of $450 to $940 ton...
This is biased high by the C/CO2 ratio because Hansen assumed Keith 2018 used tons carbon, not tons CO2. Keith 2018 did not use tons carbon, he did in fact use tons CO2. This means that Hansen's cost is overstated by a factor of 3.667, and should be $122-251 per ton removal, not $450-940 per ton removal. This $122- $251 per ton is quite similar to Keith's $94 to $232 per ton, where Kieth 2018's numbers are biased high as described above in the interpretation of costs with $0.01 kWh renewable energy.
Hansen et al., Global Warming Has Accelerated:
Are the United Nations and the Public Well-Informed?, Environment,
Science an Policy for Sustainable Dev, February 3, 2025.
https://www.tandfonline.com/doi/epdf/10.1080/00139157.2025.2434494?needAccess=true
And,
Hansen and Kharecha, Cost of carbon capture -Can young people bear
the burden, Joule, August 15, 2018.
https://www.columbia.edu/%7Ejeh1/mailings/2018/20180816_Hansen.CostOfCarbonCapture.Joule.pdf
This new narrative of ongoing Earth systems tipping activation is what the climate restoration movement is all about. Complete emissions elimination this instant can only reduce the amount of atmospheric removal and emergency cooling required; it cannot stop already degraded systems from collapsing and creating natural feedback emissions that dwarf humankind's. We have no choice but to addressing tipping before the point of no return as after mid-century, the tipping literature says these degradation collapses become irreversible. This means carbon in these systems is at risk, in quantities far more than ten times all the carbon emissions humanity has created since we began emitting.
MeltOn
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The cost of removal is somewhere north of $400, the 45Q is just 180, so you need voluntary buyers in-between
Robert Höglund
marginalcarbon.com+46 73 727 1660 (WhatsApp)
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Hi Bruce
Could I ask you to reread the Hansen & Kharecha paper. It seems to me that you've misunderstood. But maybe I have. Here's a brief extract.
Finally, note that costs are often discussed in units of $/tC, where tC is tons of carbon. A ton of CO2 is 44/12 times heavier than a ton of C. Thus, the Keith study implies a removal cost of $451–$924/tC.
This brief extract suggests that he is not in the slightest confused about the units. He also makes two other pertinent observations about why he thinks Keith has understated the costs.
In any event, I would expect these costs estimates to have changed considerably over the last several years in response to innovation. I'm not on top of the detail here but others might be.
RobertC
Bruce Melton -- Austin, Texas
Gene,
There are numerous references in Hansen's more recent works to the 1C limit to natural variation/350 ppm CO2. He too, did what we did at Sierra Club and rounded up 0.85 C to 1C for simplicity.
Hansen includes fast feedbacks. Vostok, like GrIP and the others in Greenland, reflects polar evidence. Global average metrics are not as extreme.
Another confusing factor is that 350 ppm CO2 is the maximum of the range of possible CO2 concentrations representing natural variation (Hansen's Holocene maximum below).
On not knowing that tipping has happened until after it happens....
This is a truth, but existentially inaccurate reflection of the science. Once degradation begins, it is a known that in most, or almost all systems, the systems' collapses are foregone. This is not negotiable unless the degradation factor is removed before the point of no return. We know this point of no return is about mid-century for most tipping elements already activated. That our climate culture does not recognize this fundamental could be the straw that broke the camels back and leads us into a world where natural feedbacks dwarf humankind's. It's so simple and plain, yet our climate culture continues to rely upon modeling that does not include fulfilled fast feedbacks and as a result is biased low.
Steep trails,
B
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Bruce,
I don’t understand "350 ppm CO2 is not 1.5 C, it's about 1C”in your opening line.
I guess that’s Hansen’s problem quote from his 2017 paper. So I don’t understand what Hansen was saying in2017. In Hansen’s language, I would say that 350 ppm CO2 is not moderately stricter, but substantially looser than 1.5°C.
Earth’s CO2 level was 350 ppm in about 1985.Earth’s global surface temperature in 1985 was about 0.3°C above the 1951-80 mean,or about 0.3 to 0.4°C above the 1880-1883 NASA mean.However, the feedbacks were still at the early stages.
Long-term global equilibrium temperature for 350 ppm CO2 concentration is much higher.Based on the Vostok ice core data (with Snyder’s 2016 polar to Vostok temperature conversion), it is about 3°C for 350 ppm CO2. The result is similar using CO2-°C pairs from 4-11 million years ago (means: 352 ppm & 3.4°C), without a need for polar-global temperature conversion.
On another note, I understand what you say about tipping points and agree with you.I think of tipping “points” covering a few years, which we don’t know until after they happened.Yes, we need to take action soon, before these critical systems degrade too far, and that action is primarily cooling Earth below the tipping points' temperatures. And CDR is necessary, till CO2 (& other GHG) concentrations return to safe levels.
Gene Fry
On Feb 10, 2026, at 11:56 AM, Bruce Melton -- Austin, Texas <bme...@earthlink.net> wrote:
Important!
350 ppm CO2 is not 1.5 C, it's about 1C; a tenth or two less actually.
See Hansen 2017, Figures 10 and 12 -
https://esd.copernicus.org/articles/8/577/2017/esd-8-577-2017.pdf
<Hansen Young beople's burden Figure 12 0.85C 2017 650 px.jpg><Hansen Young beople's burden 2017 Figure 10 CO2 650px.jpg>
This is a common misinterpretation that has arisen from Hansen and others' previous works on 350 ppm CO2, and one of the reasons I was able to convince Sierra Club to lower their warming target to a restoration 1 C from their previous 1.5 C. They too had assumed 1.5 C was 350 ppm CO2, like almost all across the planet that have warming targets.
Even more important: Earth systems have begun to degrade. This is called tipping activation. Once a system begins to degrade --any system, not just Earth systems; the degradation does not stop unless the thing that caused it to begin is removed or the system completely collapses. Unless we want to geoengineer the planet with cooling solutions forever, atmospheric CO2 must be restored to within the evolutionary boundaries of our Earth's systems so that tipping can stabilize, and this must be done before mid-century for most activated tipping elements or we risk total collapse of those systems with natural feedback emissions dwarfing humankind's.
An average global temperature of 1.5 C locks in Earth systems collapse for systems whose degradation (tipping) is activated. Our restoration warming target then is 1 C or less, which is the maximum natural variation of our old climate that allowed the evolution of our Earth systems. Exceeding this evolutionary boundary results in collapse of most Earth systems, as the tipping literature states, by mid-century, or significant time at 1.5 C or above.
Once again, unless we want to geoengineer forever, CDR is mandatory, regardless of individual opinions on its feasibility, speed, or costs. This mandate also must consider that once Earth systems degradation begins, those systems quickly flip from carbon sequestration to emissions; meaning that because most Earth systems are now degrading, and many documented as now emitting, there is little hope that natural systems can do anything by emit carbon, until we lower our climate's temperature to 1 C or less - back to within the natural evolutionary boundaries so their degradation collapses can stabilize and they can once again begin to sequester carbon.
MeltOn
Bruce Melton PE
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To me, the CDR sector has two roles. Building, proving and improving a toolkit that the world can use for gigatonne level of removals when it gets serious about reaching net zero. And, providing a way for companies, ambitious regions and countries and individuals to take responsibility for their emissions today while making credible claims. The story is not rapid scale, but proving, learning, and earning trust.
If you are working on carbon removal, nothing in this text should make you put in less effort. We need to keep developing CDR, test new methods, lower costs, find out what works and build demand so that we have the best tools available for global net zero and large scale legacy emission removal. But we need to do it with realistic expectations. The road ahead is narrow.
© 2026 Robert Höglund
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Bruce Melton -- Austin, Texas
Thanks for paying attention Robert. There is still a deep and existential issue that remains when assigning reality to a task that has to happen, regardless of costs.
Using Hansen and Kharecha's $123–$252/tCO2, Hansen's 2025's $2.2 trillion per year for capture and storage is 18 Gt CO2 annually, ignoring the $252/ton CO2 number because it is for $0.06 kWh natural gas which is long gone. With renewable energy, Keith's number is down to $45 per ton today with no further process enhancements, (and btw, it's much less than this using natural gas for all energy (87% of process coasts are energy) when to the producer, the natural gas is almost free, just upsize the process about 10 percent to account for the carbon emitted.) The annual removal and storage costs for 18 Gt CO2 per year at $123 ton is then is around a trillion dollars per year, not counting almost free storage with EOR.
We spent about $5.3 trillion on health care in the US alone in 2025. A trillion bucks a year is no small thing, but what's the big deal, this is a mandate. We cannot also geoengineer forever. This means temporary emergency cooling, and removal as fast as we can pedal so we can stop geoengineering as soon as possible. Most importantly, if we do not return our climate's temperature back to within the evolutionary boundaries of our collapsing Earth systems by mid-century, the solutions become far more complicated.
The underlying concept is important to the future of our climate. What is conveyed to the reader via Hansen's (and many others' work), is that carbon capture doesn't exist or if it is it is too dang expensive. Is it? How much is too expensive to save our advanced civilization as we know it? Is air capture really nonexistent? Of course it is not. It has existed for well over a hundred years, is very mature, widespread in industry, and with components that are even more widespread. See the link below, History of Carbon Dioxide Removal. All we have to do is gigascale these processes like we gigascale virtually everything on this planet of eight gigapeople. This will not be difficult, nor exorbitantly expensive relative to other giga things we do on Earth every day. It will take a bit of time, but it will be nothing new to humanity. See the link below to Gigapeople, Gigachickens and Gigashoes.
And here's a confirmation thought: Would Oxy have contemplated building Stratos if the cost were greater than revenues generated?
Hansen and Kharecha's other issues with Keith 2018? That,
hydrocarbon fuels created from contemporary carbon do not create
negative emissions? So? Aren't we trying to decarbonize too?
Doesn't avoidance of fossil carbon emissions count on the road to
net zero? And the $10 to $20 cost for carbon storage. Once again,
So? This is little money relatively, and the costs are down to $5
ton btw and almost free with EOR - but EOR creates more emissions?
It does not if one is getting paid for leaving CO2 in the ground
with IRS 45Q. The concept that EOR is carbon positive is not valid
(+/-). The process of enhanced oil recovery with CO2, where all
the CO2 that can be removed from the recovery well is recycled for
injection into the next well to recover more product; the
literature on this process shows it is about carbon neutral in
most plays, it's not carbon positive. in other words, half the CO2
pumped in cannot be recovered because it becomes trapped in the
geology. When the point of diminishing returns for recovery is
reached, there is lots of room in the play for more CO2 to be
pumped in. When the infrastructure already exists to capture CO2,
then pipe it to the recovery well and inject, and the cost of
capture is significantly less than the 45Q pay, why would a
producer not keep pumping CO2 into the recovery well until it is
full , so that they reap the pay from 45Q?
Steep trails,
B
History of Carbon Dioxide Removal
https://climatediscovery.org/History_of_Carbon_Dioxide_Removal_Draft.docx
Why our giga task of engineered cooling solutions will be nothing
different than life on Earth every day.
https://climatediscovery.org/Gigapeople_Gigashoes_and_Gigachickens.docx
Director, Climate Change Now Initiative, 501c3
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Bruce Melton -- Austin, Texas
Oxy process in the Permian is Keith's process at +/- $45 from known scaling factors from existing components and renewable energy at $0.01kWh, utility scale, on-site generation for the electric component of about 40 percent of energy costs that are 87% of total process costs. This is Keith's big reveal, and the reason why they published. Other's processes are typically proprietary, and publishing would reveal their secrets. All the components and their scaling are existing and shovel ready for Keith's process. For other processes, of course we will no know until we know. This is one of the challenges of science versus proprietary tech. There are trillions of $$$ of revenue at stake with just 45Q. The lion's share will go to those first to market, that can amass the most infrastructure the fastest.
I would love to look at publishing of any kind on costs today of $400 ton.
Steep trails,
Bruce
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I am talking about the actual cost today, in reality, not academic estimates
Robert Höglund
marginalcarbon.com+46 73 727 1660 (WhatsApp)
Bruce Melton -- Austin, Texas
I want to reiterate as my last email did not fully discuss the error in Hansen and Kharecha 2018.
The quote from Hansen and Kharecha 2018 as you cited, "Finally, note that costs are often discussed in units of $/tC, where tC is tons of carbon. A ton of CO2 is 44/12 times heavier than a ton of C. Thus, the Keith study implies a removal cost of $451–$924/tC."
The conversion from CO2 to C results in a mass that is less than the mass of CO2, where the atomic mass of CO2 is 44 g/mol and of C is 12 g/mol.
1 ton CO2 X (12/44) = 0.27 tons C per ton CO2, and
Using Hansen's numbers that include preparation of CO2 for
storage and injection of $123 and $252 per ton CO2:
($123 and $252) X (12/44) = $34 to $69 per ton C
Hansen assumed Keith 2018's cost were $451–$924/tC, or 13 times more than reality.
Steep trails,
B
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Hi Bruce
Don't you have to divide by 12/44, not multiply? Removing 1t of CO2 only removes 12/44t of C. So, to remove 1tC you have to remove commensurately more CO2. It costs more to remove 1tC (in the form of CO2) than it does to remove 1tCO2.
Your 13 times more is 3.664 squared because you're multiplying when you should be dividing.
Robert
Bruce Melton -- Austin, Texas
Ah! https://www.cdr.fyi/ is the cost of carbon credits, not the cost of removal. Big difference. Cost of credits is what the market will bear. Cost of removal is the cost of removal.
Thanks for the clarification. This is likely another of the big challenges with the cost of air capture - it is confused with the cost of credits, as well as those costs of removal in the literature that use poor process assumptions and enthalpy backwards in their calcination calculations.
Steep trails,
Bruce
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The average price in CDR.fyi is $490, but that's already subsidized price by 45Q, Canada's capex rebate etc, and aggressive forward selling assuming future cost drops.
I don't think anyone has so low costs as $400 today, but it's a reasonable cost to assume in the near future.
David Price
“A ton of CO2 is 44/12 times heavier than a ton of C.”
On Feb 13, 2026, at 8:40 am, Bruce Melton -- Austin, Texas <bme...@earthlink.net> wrote:
<History of Carbon Dioxide Removal Cover Oktoberfest Bavarian Beer Girl attrib-Hacker-Pschorr Oktoberfest Girl 650 px border.jpg>
Why our giga task of engineered cooling solutions will be nothing different than life on Earth every day.
https://climatediscovery.org/Gigapeople_Gigashoes_and_Gigachickens.docx
<Gigachicken and Astrodome, Wikipedia an Pixabay anotated 650 px.jpg>
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Michael MacCracken
Dear David--Jim could do it because it is true. Scientists like to track atoms and so focus on the C atom and express global emissions in GtC. Negotiators seem to like to deal with bigger numbers so taking actions to cut emissions counts the mass as well of the oxygen atoms, and have often focused on millions of metric tons of CO2 (so MMtCO2) and sometimes add an "e" when wanting to add in the relative influences on other species compared to CO2. So, there is a difference and it is very important to distinguish what one is talking about. Global emissions are roughly 10 GtC/year or can be said to be 37,000 MMtCO2. Not saying specifically which approach is being used can make things very confusing.
Mike MacCracken
David Price
On Feb 13, 2026, at 12:12 pm, Michael MacCracken <mmac...@comcast.net> wrote:
chris....@btinternet.com
Robert,
Bruce’s conversion is correct. Using the exact atomic weight of carbon of 12.01, multiplying the CO2 figure by 0.2727 recurring (12/44) is the same as dividing the CO2 figure by 12/44 i.e., 3.667 that is the reciprocal of 0.2727. However, the conversion from CO2 to C is usually expressed as being divided by 3.667 with the conversion the other way being to multiply the C by 3.667 to get CO2.
Chris.
robert...@gmail.com
Hi Chris
Maybe it's just too long since I did any school maths!
The issue here is not that 1kgCO2 contain 12/44 or 0.27kgC. That's not disputed. The issue is the application of that ratio to determine the cost per tonne of CDR when switching between $/tC and $/tCO2.
Earlier in this thread Bruce cites Keith 2018 costs of $94 to $232 per ton CO2 removal. He then criticises Hansen who claimed a cost of $450-$840/t on the basis that Hansen had wrongly assumed that Keith was using Tc and not tCO2. In fact Hansen made no such error as the extract I cited showed.
The point here is quite simple. When you pay, say $100, to remove 1tCO2 you only remove 0.27tC. So if you want the corresponding cost to remove 1tC you have to gross the cost up by dividing it by 0.27 or multiplying it by 44/12.
All I'm saying is that Bruce did the reverse and that's why he wrongly asserts that Hansen's figure it out by a factor of 13 (=3.6672).
Robert
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Bruce Melton -- Austin, Texas
What remains is the error. Errors happen in academic literature, reviewers are human. Another error that has persisted and create havoc in the understanding of facts with air capture is the enthalpy error used to suggest that air capture is wildly more inefficient than air capture because of the concentration hypothesis. Peer review and authority are not infallible. We on these lists should know this above all. Our charge is to overcome the errors and misinterpretations; the psychology and gut feelings, and bring the truth to the world that 1.5 C is too warm, and that too much time above 1.5 C creates irreversible natural systems collapse cascades with feedback emissions dwarfing humankind's. This is not a part of our climate culture because of 11 understating biases in climate science, advocacy and reporting. The facts exist and we know them from peer review, but the 11 understating biases allow extremely authoritative entities to overcome reality just like Hansen and Joule's authority allowed many of us to believe that Hansen's numbers were correct.
Steep trails,
B
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Hi Bruce
Could you clarify the typo here: the enthalpy error used to suggest that air capture is wildly more inefficient than air capture.
Also, could you respond to the suggestions that you might be wrong about the error in Hansen's numbers - I assume you're referring to his cost of CDR numbers.
Out of curiosity, what are these '11 understanding biases'?
Robert