Cassandra has moved. Ugo Bardi publishes now on a new site called "The Seneca Effect."

Tuesday, May 8, 2018

Negative Emission Technologies: maybe we can still save the world, after all!

The ancient Egyptians knew how to manage the commons. A single central authority managed the Nile river, to make sure that everybody had enough water for their needs. Could we do the same for our atmospheric commons and save the world by using negative emission technologies (NET)? Above, a Pharaoh (probably Ramses II) receives the crown of Upper and Lower Egypt.

Before I went to hear Klaus Lackner in Les Houches in March 2018 (image on the right), I had a very poor opinion of direct atmospheric capture (DAC) and negative emission technologies (NET).  If you had asked me, I would have said that there is no need for these technologies: why can't we just avoid emissions, instead? And if you were to tell me about "artificial trees," I would have told you that Mother Nature spent some 350 million years to develop trees, and She knows better than us how to remove CO2 from the air.

Well, I changed my mind. I came out of Lackner's seminar convinced that DAC/NET may give us a fighting chance to survive. Consider that it is perfectly possible that we already passed the "tipping point" that will lead Earth's climate to move to a different climate state. In that case, reducing emissions or even zeroing them will not help us. And, in any case, we are not doing that fast enough. So, DAC/NET as the last hope to save civilization? (*) Possible, yes, of course not really likely given the situation but, who knows? Let me explain.

First of all, let me state a point that is clear to me: the energy transition is NOT a technological problem. We could go through the transition fast enough to avoid running out of energy and before climate change destroys us. But only if we were willing to invest enough in the transition, and we aren't.

So, the problem is really financial and political. And, at present, it seems to be impossible to solve since the idea that civilization (and perhaps humankind) is at risk is just not penetrating into the consciousness of the decision-makers.

The main problem is that we haven't been able to find a way to frame the message in the right way. Let's imagine a dialog between a scientist and the public.

Scientist: We have a big problem with CO2 emissions. The atmosphere is going to overheat, the tropics will be desertified, the sea level will rise and swamp all the coastal cities, lots of people will die of starvation. And more dark and dire things. 

Public. Ouch, that's terrible. What can we do to avoid that? 

Scientist. Well, you have to change your lifestyle. Give up your car for a bicycle, turn down your thermostat, no vacations overseas, that kind of things. 

Public. I see...  Mr. Scientist, but are YOU doing that?

Scientist: Well, I do what I can but, you see, there is this thing that we scientists call the "h-factor" and the higher it is, the higher our salary is, so I have to attend international conferences, take planes, travel, all that. . .

Public. You know, Mr. Scientist, I think you are part of a conspiracy of scientists who invented the idea of global warming in order to siphon money out of the pockets of taxpayers. And, by the way, on the next elections, I am going to vote for someone who will defund your research so that you'll stop bothering me with this scam.

See the problem? Instead, let's imagine that the last part of the dialog goes in a different way

Scientist. A little CO2 in the atmosphere is a good thing, but too much of it becomes a waste problem which may create a climate disaster.

Public. So, Mr. Scientist, what do we have to do to avoid that? 

Scientist. Well, we have ways to remove the excess CO2 in the atmosphere. It will cost you some money, of course, but it is just like for the household waste you produce. Every good citizen has to pay to have their waste taken care of. 

Public. But what are YOU doing about that?

Scientist: Me? Of course, I am going to pay for the removal of my CO2 waste, just like everybody else. 

Public. Hmmm...... I see. How much that would cost?

So, the idea of atmospheric CO2 removal - NET - could be just the kind of message that goes through and that can be understood by almost everybody. Lackner himself confirms that from his experience in Arizona, where he works. Arizona is not known to be a place where people agree with the idea that AGW exists and is a problem. But Lackner reports that when the climate problem is framed in terms of "clean up your mess," then even the most hardened science disbelievers may grudgingly admit that something needs to be done. And to the people who insist that "CO2 is not a pollutant" you can just answer, "nor is coffee, but if you spill some of it on your carpet you'll want to remove it."

Of course, a good message is useless if applied to a technology that can't work but, in this case, I think there are reasons to think that DAC/NET could. It is a complex story, but you can start looking at it from Lackner's papers at this link. You can also find useful data about costs and about the energy involved at this link. For something not academic, see this article on The Guardian.

You'll see that this technology is a thoroughly studied subject, not an idea just thrown in. And it has a number of advantages. One is that it is much more effective than the IPCC idea of BECCS (bioenergy and carbon capture and sequestration) since DAC plants need no water or fertilizers and they can be placed anywhere, even in the middle of a desert. Then, DAC machines are flexible: the CO2 removed from the atmosphere can be sequestered underground but also, if needed, used to produce fuels and chemicals: you can "tune" the removal without having to leave the machines idle.

A rough estimate of the energy involved in the DAC task says that about 10 GW of continuous power would be required in order to remove one billion tons of CO2 per year. Since we are emitting some 38 Gtons of CO2 per year, the energy needed for DAC is large, some 500 GW per year of continuous power. But the world consumes today about 15 TW of power, so it is not unreasonably large. Of course, it has to be RENEWABLE energy, otherwise it would make no sense. Using fossil fuels to remove CO2 from the atmosphere would be self-defeating. So, the effort would consume most or all the renewable energy we are producing nowadays: we would have to step up production of at least one order of magnitude, probably more than one. But it is not impossible.

But don't think of NET as a way to keep burning more and more fossil fuels. It is an emergency tool to remedy the damage we have already done: if we keep at doing more damage, then it will be useless. It needs to be coupled with a rapid reduction in emissions and the deploying of renewable energy sources. Note also that the amount of CO2 that can be stored underground is not infinite.

Then, it becomes a question of cost and time. We need to build millions of DAC machines in a few decades if we want to control the CO2 concentration in the atmosphere and bring it to levels that we judge safe. Impossible? No: during the second world war, the world managed to produce some five million tanks and military vehicles in about 5 years. In fifty years, a much larger economy such as the present one could well produce tens of millions of DAC machines, also considering that one of these machines is probably less complex and less expensive than a battle tank (to say nothing about being much more useful).

In the end, the essential point of this technology is that it is truly global: DAC machines can be placed anywhere in the world and their effects will be global. As a consequence, operating them requires a global governance system. The situation is not different from that of the ancient Egyptians who needed to manage the Nile in order to ensure that there was enough water for irrigation. They succeeded, so why can't we? It is a great occasion for humankind to get together for a worthy task: managing the atmosphere as a global commons.

Below, King Scorpion II engaged in digging an irrigation ditch in ancient Egypt, in other words, managing the commons!

(*) Note that DAC/NET is absolutely not the same thing as "CCS" (carbon capture and sequestration) intended as a retrofit for existing and new coal plants. Coupling coal with CCS is just an expensive way to keep going with obsolete technologies and will do more damage than good if it is deployed.


  1. > As a consequence, operating them requires a global governance system.

    Oh, no problem then.

    1. If there is a will, there is a way.

    2. If there had been a will, we would have found a way by now.

      I mean, it is one more ingredient in the fight against global warming. Maybe it will get traction. Maybe the leader of a large country will leverage DAC to solve some geopolitical problem. Maybe it will prove useful in rebalancing the world's economies and trade flows. Maybe we could use DAC to stem the migrant flows and "help them at home", as some have been calling for.

      I can think of many possible applications. Everything is possible.

      But I do not think that the world necessarily needs DAC to achieve any of those results. Problems are aplenty. Solutions are aplenty. The world only needs someone to connect the two.

      That is exactly what we are missing. DAC will not change that.

  2. Thanks for giving some hope this time.

    Is this method making its way to decisionners as far as you know?

  3. I don't think that a Negative Emission Scenario could be reachable, inside a Fossil Fuels Scenarios by mankind.

    1ST thing, from industrial revolution until nowadays, mankind history never ever had a negative gas serra emissions. Does it mean something or not?!

    2ND Kyoto was ineffective, probably Paris will be ineffective too. Will those stuffs mean something?!

    3RD thing, I agree, for sure Nature does it better: oceans and trees are the best CO2 negative emission technologies available for mankind, but oceans are under acidification stress, this not good thing for underwater world, those places are destroyed also by violent mankind fishing. So at the end of the day, if mankind still wants fishing in future, I think mankind has to use forests only, to achieve and efficient direct atmospheric capturing of CO2 emissions already in the world atmosphere. It will need long time, may be 700 years to return under 300PPM (and without negativev actions of the siberian methane hydrate bomb with positive feedback) but this is it.

    4TH thing. Negative Emission Technologies are not mature stuffs, for the moment there are no solution for capturing gas serra emissions in substantial quantity for being effective. Human Technologies need power, if power comes from fossil fuels, there is no solution at the CO2 problem. Gas serra emissions have to be captured, stored, water proofed, put inside the Earth in safe places, otherwise the natural water cycle will restore all those stuffs in short term into the Earth atmosphere. For doing that, for long time, it will need lots of energy so... that is a problem!

    5TH thing. For doing this big terraforming action, it will be necessary not only energy, but also wide and big areas otherwise the attempt of terraforming will be ineffective, because Earth atmosphere is a very giant volume. If we put those SciFi terraforming hardware on land, mankind will destroy fertile land so less food it's not a good idea under a over populated Earth during wide and rising climate change damages. There's no way on putting this SciFi hardware in the sea, because those stuffs will cost too much and there's the acidification risk for the seas. The only place where mankind should put wide big terraforming hardware, are in the deserts. Deserts seem a nice place where to develop termodynamic solar hydrogen value chain in zero emission CO2 to power SciFi hardware for terraforming Earth atmosphere. The idea is pretty good, but for sure it's too late: 402PPM already means +4°C of global warming, and mankind passed through the +2C global warming in 1960s. For sure mankind is in late, but nobody is running in the right way.

    6TH thing. Negative Emission Technologies for burning CO2 in coal power plants run for CO2 emission of those coal, and the process don't capture the other CO2 already in atmosphere, so the NET is a false solution for CO2 capturing.

    7TH thing. Metane is a powerful gas serra, much stronger than CO2 and the hydrate methane melting in Siberia with positive feedback it is a bad, sad, uncontrolled and uncontrollable stuff for mankind.

    Have a nice day!

    1. It's not question of hope, for sure it's matter of lacking of politic vision, and lots of lost opportunities 20 or 10 years ago especially for the future issue of the Punic War II in the Mediterranean area.

      The model for changing scenarios are two key variables only: 1-leaving fossil fuel by mankind, 2-how the things turn from bad to worse in siberia about methane hydrate melting issue. The 1ST variable is uncontrolled by the I world, because II,III world can prefere fossil fuels for growing up (on following the economic history-path of I world), the 2ND variable is a stuff totally uncontrolled and uncontrollable for mankind. Even it is already possible changing things from one scenario to another, unfortunately the scenarios seem pretty sticky, with lot of inertia.

  4. There is no will. And no hope. Environmentalism consists of buying a hybrid car and recycling plastic packaging.

    1. This is the reason that could make Ugo right.

      There is no will because actual (and expected near future) actions are drived by selfish politics.
      Paris and others don't work by now because the negative consecuences of actual acts will occur in the future. Because future people is not here, only some people with wisdom to see that, there is little force to change actual policy.

      As the consecuences turn true, the cost of raise more and more CO2 become more and more costly that do it, the will to change the direction will grow. But from traditional perspective (stop, but not reverse emissions), that will be too late.
      But with negative emissions that could change. Once everyone notice that it's not a conspirancy, that all will be lose more than change the course of actions, near everyone will agree to take whatever be needed, including geoengineering and negative emission technologies.
      In fact, that will turn mandatory and a new market. In little time, a lot of people will embrace the new politics.

  5. I have been following DAC development for more than 10 years but recently have gone back to where you started - real trees are vastly better than artificial ones, just as real whales are vastly better than the artificial kind (ocean surface fertilization). The world’s first negative emissions power plant began planning in 2007 and went into operation at the end of 2017 in Hellisheidi, Iceland. The facility uses the “free” energy of a geothermal power plant coupled with a DAC unit to capture CO2 from ambient air, flush the filters into water and pump it more than 700 meters underground. There, the CO2 reacts with the basaltic bedrock using “enhanced weathering” to form solid calcium carbonate (limestone) after about two years. At full operational scale, the system is expected to capture 50 metric tons of CO2 annually. The cost is in excess of 10 million dollars.

    50 tons is about same output of a single US household in one year. The cost of each ton, even amortized over a century, will run into the thousands of dollars, and needless to say, there are only a limited number of places on Earth where such a scheme could even work.

    Direct removal can also be accomplished by minerals that soak up carbon from the air, such as peridotite, essentially turning air into stone. There is enough peridotite in Oman and the neighboring United Arab Emirates to absorb 33 trillion tons of CO2, equivalent to 1,000 years of present-day emission rates. Getting it to the surface and milled in such as way and then continuously soaked in water to actually do that is another matter.

    There is no simple technical solution. Even though renewables are now deploying faster around the world than all other types energy, they have yet to replace a single joule of fossil energy. They are all ADDING to the global electric supply, as are hundreds of new coal plants in India and China. It is the exponential function, after all, wherein each doubling takes as much as all the previous supply combined.

    That said, there is indeed a way out, which is why Kathleen Draper and I have co-authored a book for Chelsea Green called Carbon Casades: Redesigning Human Ecology to Reverse Climate Change, which is due out later this year.

    Spoiler alert: it is all naturopathic. If you want a first order approximation of our formula you can read the excellent paper by Griscom, et al from PNAS last year - . Griscom's team only took drawdown to 23 Gtons and as you correctly point out above humans presently emit 38 Gtons. Griscom's limiting factors were feedstocks and sink locations. We demonstrate how we can blow through 38 and keep going until atmosphere and oceans equilibriate around 230 ppm in this century.

    Without costly and energy consumptive artificial trees.

  6. @ Albert Bates
    The natural reforestation seems to me the big only very good idea to fight climate change in effective way
    I totally agree with that solution.

    But on reading the plan, may be is it a bit optimistic for the next decades for the CO2 capturing rate?

    May be I'm wrong, but it's not clear which continents will have to do the bigger part of the reforestation. May be north america and south america?! But Canada is destroying wide locations with shale oil/gas and bituminous sands, and in USA new insects are destroying large part of nice evergreen forests. Which solution can fix those problems? Mediterranean area (without the AMOC shut down) will be a dry desert. Temperate clima areas will displace towards north while dry and desert zones will enlarge their portions in the continents.

    Climate change also means the desert rising, dry crisis, tornados and uraganos damages, costal flodding and lacking of fresh sweet water, massive migration inland for cities displacement. How an action of massive reforestation, can face off those rising crisis too in the next decades?!

    Overpopulation needs more food, so more fields and more houses and less forests. More metropolis means more energy power plants: it seems to me quite hard to stop those process in the II world, they want to grow up and improuve their lifestyle. Those targets are in opposition with reforestation, how could be possible to persuade II world governments to act reforestation rather than improuve BAU?!

    The natural reforestation don't capture methane emissions, actually siberian methane hydrate trapped in permafrost are melting in a low rate and they increase the climate change for a small fraction only, unfortunatly there's concrete risks that things in the next decades can turn from bad to worse. Mankind really need a new black box technology stuffs to fix this problem just in case of necessity, but none seems interesting about that: why?!

  7. My faith in the government's of the world is not at all positive. Still I would welcome a little hope.

    1. Hope only prolongs the agony of man, I prefer fear . Hope leads to procrastination ,fear leads to action .

  8. From one of the links supporting the concept (

    • Direct air capture will not become less expensive than capture of CO2 from concentrated streams. Thus, a cost-effective deployment would be preceded by nearly complete decarbonization of all major point-source emissions, such as power plants.
    • DAC could have a role as a strategy for compensating for distributed emissions from transportation and buildings, but it would need to outperform end-use efficiency, zero-carbon electricity, and zero-carbon fuel. Specifically, CO2 removal strategies may be needed to decarbonize the more recalcitrant distributed uses and to eliminate the residual emissions from zero-energy strategies.
    • The requirement of significant positive net CO2 removal from the atmosphere will constrain DAC systems to operate with low-carbon energy sources.

    So first we have to decarbonize all electricity production, then use a lot more zero carbon electricity to take CO2 out of the atmosphere from other sources. Easy peasy.

    1. Yes... something like that. And we need to electrify the existing non-electric fossil fuel parts of the economy - mass motoring and air transport come to mind. As an afterthought the total economy must grow its delivered NET utility while investing in all the above. And this ever bigger economy must maintain and continually replace all its structures as it goes along. It sounds a nice idea and 'we' could replace all the war economies - they are indeed wasteful - but...

  9. Demanding less goverment debt and stupid susbsidies is more achievable than manufacturing 10 million fake trees and ramping up both renewable energy for them besides human consumption.

  10. well, maybe send a couple of emissaries from Dr. Lackner's lab to Elon Musk's juggernaut. get Musk some tax breaks and subsidies, show him the money, and maybe Musk will open a new 'Tree Making' division out there in the desert.

    we need a lot of those trees and then get them distributed, operational, and maintained in a pretty big hurry! but like we needed jeeps in WWII, and because GM had the production systems and conduits at scale to do it, that was where it went.

    maybe tell Musk without a launching pad (i.e., planet earth) he isn't going to make it to Mars anyway...

  11. The world is going to compete more, not cooperate more. 2017 was the year of greteast military spendings since cold war.

    And DAC will be far too much expensive. I found in one of Your links that the cheapest predictable solutions will cost 60$ per tonne of CO2 captured.

    38 gigatons is tons. x60 = 3 trillions 280 billions of dollars. This is tle lowest predictable cost of annual CO2 emission. To neutralise global warming we must sucks much more than one year emissions.

    And all in the age of low growth, old populations, huge public debt, declining EROI of major energy sources and sharply growing global tensions and competition.

    1. To put that in perspective :

      1 ton of CO2 is produced by burning ~3 barrels of oil.
      ~3 barrels of oil currently cost ~$240

      Also, Sweden supposedly has a ~$140/ton carbon tax...
      but I don't know what % of their emissions is taxed *in practice*...
      and also they seem to have started to import wood from Finland and Russia to burn it for power/heating... which is not taxed, but how long before it's consumed faster than the forests grow and it therefore stops being carbon neutral?
      (not to mention their manufactured product imports (that therefore likely weren't taxed for their manufacturing), or the $11 Billion of "mineral fuels" that they export per year !)

  12. Thank you for this interesting perspective. I am a bit suspicious about the low energy cost - it just sounds too good to be true. What is included in the estimate? Is it just the absorption operation itself, or is it truly the total energy of building a plant, producing and replacing the absorption chemicals, releasing absorbed CO2 into a form that can be further processed?



Ugo Bardi is a member of the Club of Rome, faculty member of the University of Florence, and the author of "Extracted" (Chelsea Green 2014), "The Seneca Effect" (Springer 2017), and Before the Collapse (Springer 2019)