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Air Capture

Filed under: — group @ 30 March 2008 - (Español)

Guest Commentary by Frank Zeman

[This is one of an occasional series on the science of mitigation/adaptation/geo-engineering that we hope to continue. Since this isn’t our core expertise, we’d especially appreciate balanced contributions from other scientists.]

One of the central challenges of controlling anthropogenic climate change is developing technologies that deal with emissions from small, dispersed sources such as automobiles and residential houses. Capturing these emissions is more difficult as they are too small to support infrastructure, such as pipelines, and may be mobile, as with cars. For these reasons, proposed solutions, such as switching to using hydrogen or electricity as a fuel, rely on the carbon-free generation of electricity or hydrogen. That implies that the fuel must be made either by renewable generation (wind, solar, geothermal etc.), nuclear or by facilities that capture the carbon dioxide and store it (CCS).

There is however an alternative that gets some occasional attention: Air Capture (for instance, here or here). The idea would be to let people emit the carbon dioxide at the source but then capture it directly from the atmosphere at a separate facility.

The removal of carbon dioxide directly from the atmosphere is a natural phenomenon that occurs in the surface ocean or during photosynthesis. Ocean absorption is a result of both the higher concentration of CO2 in the atmosphere and the alkaline nature of seawater (Note that this absorption that is leading to the “other” CO2 problem, ocean acidification – which may prove detrimental to coral reefs and other organisms that use carbonate). Land-based air capture is an effort to enhance this mechanism at an industrial scale so that CO2 can be removed from the atmosphere under controlled conditions. Given that it is performed under controlled conditions, we can use more alkaline solutions to improve the rate of capture without adversely affecting the biosphere.

Industrial air capture is based on the absorption of CO2 using alkali earth metals such as sodium or potassium. The process is a variant of the Kraft Process used in most pulp and paper mills and as such, benefits from a long industrial history. The CO2 is absorbed into solution, transferred to lime via a process called causticization and released in a kiln. With some modifications to the existing processes, mainly an oxygen-fired kiln, the end result is a concentrated stream of CO2 ready for storage or use in fuels. An alternative to this thermo-chemical process is an electrical one in which an electrical voltage is applied across the carbonate solution to release the CO2. While simpler, the electrical process consumes more energy as it splits water at the same time. It also depends on electricity and so unless the electricity is renewable or nuclear, will result in the storage of more CO2 than the chemical process.

If the technology is well established and, aside from the oxygen combustion of lime, dates back over 50 years, what stops it from being used and what might change in the future?

The main barrier is the efficiency of the energy requirements during the reducing process. Air capture requires energy to move the air, manufacture the absorbing solutions and solids as well as to produce the oxygen, fuel and make up chemicals. All of these items will result in additional CO2 emissions, which reduce the efficiency and therefore the benefits. The second important consideration, and maybe the dominant one, is cost. Air capture has to be more economical than the proposed alternatives (hydrogen, electricity, renewables, greater efficiency etc.). It should be stated clearly that air capture is not a viable alternative to capture at large, point source emitters such as power plants since it will always be more efficient to capture and store carbon dioxide from more concentrated streams. So while there are any non-CCS fossil fuel plants, Air Capture is a non-starter.

But recent suugestions have re-thought air capture as a thermal process. The early incarnations of air capture used electricity as the energy source and therefore depended on carbon-free sources. A thermal Air Capture system uses heat that can be generated on-site, reducing the inefficiencies associated with producing electricity, but of course it still needs a source of (carbon-free) heat. Notably, this implies that air capture could reduce greenhouse gas emissions independently of developments in the power generation or transportation sector. Preliminary experimentation has shown that causticization can occur at ambient temperatures and that conventional vacuum filtration is sufficient to avoid large evaporation penalties. These developments reduce the total energy required for the process by about half compared to the conventional method and thereby reduce the amount of CO2 that would need to be sent to storage.

However, the cost of air capture is still basically unknown. Estimates have varied wildly and real numbers will only come from pilot projects over the next few years. In some sense, that puts this technology on par with the hydrogen economy with expansion potentially starting sometime after 2015. For now there are far easier (efficiency) and cheaper (power plants) ways of reducing emissions of CO2 and so air capture is not a replacement for other efforts to reduce emissions. But in the long run, all carbon sources will require mitigation – including the transportation sector – and at that time air capture could be the most cost effective option for some sources. It is not any kind of panacea though.

238 Responses to “Air Capture”

  1. 101
    Chris Dudley says:

    Phil: (#88) Thanks for pointing that out. I’d appreciate a link to the discussion. It seems to me that since the anticipated growth is dependent on sea level rise, then some slight increased solubility owing to the freshening of the oceans could be anticipated.

    I expect that we have already provided the oceans with more than enough calcium owing to soil erosion from farming. Lack of sunlight from turbidity and silting or lack of oxygen from hypoxia seem to be the current limits we are setting, along with an unsuitably rapid change in water temperature.

  2. 102
    David B. Benson says:

    Edward Greisch (74) — If you go back through the comments from the beginning, yoou will find my (longish) post on biocoal.

  3. 103
    Frank Zeman says:

    Some more comments:

    (54) The electric route, as proposed by LANL, tends to consume at least as much electricity as the thermal process we’ve proposed. I guess the challenge for nuclear systems is to establish a cost for unsubsidized electricity that includes waste disposal. One interesting development on the nuclear front is the PBMR reactor taking shape in South Africa ( Certainly it’s likely that a suitable wind site exists to run the electric process. Also a suitable solar thermal site may be feasible.

    (58) The pressure at the end of the process is 80 bar, suitable for storage. The 37 kJ sounds right for the thermodynamic minimum but in practice it is much higher. To lower the output pressure to 17 bar might chop 20 kJ off the process.

    (59) Absolutely, capture from power plants and industry will likely be cheaper. Getting those sources can capture about 50% of current emissions, air capture is concerned with the portion of the remainder that cannot be eliminated by efficiency and renewables.

    A general note on biomass. Biomass systems would likely be cheaper than Air Capture at current biomass costs ($60/tonne). As mentioned, you run a power plant off biomass, get green power and capture the CO2. There is a great quote from the IPCC WG3 report that states roughly that any biomass solution implies the resolution of issues surrounding food production, water for irrigation, biodiversity and land use change. Witness the rise in food prices brought on, in part, by the ethanol boom. Global bimass productivity is estimated at 60 Gt carbon per year. We now consume 8 Gt C or so for energy and agriculture uses 10% of the land (or so). So what are the effects of devoting around 25% of the global biomass production to intensive agriculture? Who gets to decide when you grow food and when you grow fuel? Air Capture can also get CO2 at a rate at least 100 times faster, per unit land area, than biomass growth. I do think that agricultural wastes should be used with attention so that the waste does not become more valuable that the product.

    Storing carbon in the surface environment, as biomass or biochar, is feasible but high risk as it is very labile or mobile. If we charge a field with carbon and then it is tilled then the carbon goes back to the atmosphere.

    As always, the first thing is efficiency, capture and power plants and continued growth in solar panels.

  4. 104
    Phillip Shaw says:

    I have been trying to post what I feel is a cogent and insightful comment but it keeps getting kicked out as spam. For the life of me I can’t figure out why. Frustrating! The error message says to contact “us” if it continues to be a problem. Who is this “us” of which it speaks?

  5. 105

    From Eli Rabett’s comment

    for many years the Canadians operated thorium reactors (CANDU).

    The CANDUs are still operating, indeed a new one started up in Romania last year, and a clone in India, but have never run on anything but plain UO2.

    It makes sense that a never-run CANDU core could start up with a small fraction of its fuel bundles containing instead ThO2, and as it cooked slightly increase this small fraction, but CANDUs have always been independent both of uranium enrichment and of fuel reprocessing, and without reprocessing, fractional substitution of uranium with thorium would be the extent of it.

    40 billion barrel-of-oil-equivalents per year — ten times the use rate — seems to be the recent rate of discovery of uranium deposits, driven by a U price of almost $2/BOE, about a year off a brief spike over $3.

    Adding a little complexity to core management and fuel fabrication in order to save a third or so on uranium hasn’t, I guess, seemed worthwhile, and probably won’t seem so any time soon. (Spent thorium, i.e. thorium that has been converted to 233-U and then to fission fragments, does not differ in any essential way from the mix, in existing CANDU spent fuel, of fragments from the fission of about 60 percent 235-U, 40 percent 239-Pu.)

  6. 106
    Ike Solem says:

    Really, this whole issue has to be viewed in the context of carbon cycle changes as global warming proceeds. Thus, readers might want to look at a previous post on RC:

    Positive feedbacks from the carbon cycle, May 2006

    We know that the Earth’s biosphere has been in photosynthetic and respiratory balance, more or less, during the last 10000 years or so (because atmospheric CO2 was steady), even though that balance is on the order of 100 gigatons of carbon back and forth each year (humans add some 6-7 gigatons of carbon per year). The main issue is that warming soils, permafrost and oceans could start outgassing CO2 that has been locked up for several million years as methane or organic carbon. The system will eventually reach a new equilibrium, with sea levels many meters higher than they are now, over an unknown time period – 100-1000 years?

    If there is such a tipping point in the carbon cycle, such that a complete halt of human CO2 emissions would not halt the (slower) rise of CO2 in the atmosphere, then we should try very hard to avoid it.

    In order to do that, we have to stop adding fossil carbon to the atmosphere, and that means coming up with alternative energy supplies to replace fossil fuels. There is literally no practical way to capture carbon from coal combustion. As the author points out:

    3) The best estimates for the energy consumption of AIr Capture is 350 kJ/mol CO2. I think we can get that down to 250. The heat released from coal is 400 kJ/mol CO2 with all other fuels higher owing to the hydrogen present. While not super efficient, we regularly accept only 35% conversion of coal to electricity.

    Practically, what that means is that we would have to build a massive new facility next to each coal-fired power plant on Earth, which would be dedicated to air capture, and which would consume, according to best estimates, 87.5% of the energy produced by the coal fired power plant, but, considering process inefficiencies (i.e. that 35% coal-to-electricity conversion), you’d be lucky to break even. It sure looks like a perpetual motion machine. The complete failure of the highly promoted “FutureGen” coal-carbon-capture plant (after something like $1 billion was dumped into it!) is more evidence that this is a hopeless quest.

    It’s a bit like asking car companies to build cars that capture all the CO2 emitted by the internal combustion engine and store it all as carbonate bricks in the trunk as you drive down the road. Any auto engineer would laugh in your face at such a request – but we have many university departments devoted to this nonsense, such as Stanford’s ExxonMobil-funded and controlled “Global Climate and Energy Program” (which Exxon executives claimed was evidence of their support for renewable energy in the recent Congressional hearings).

    Sally Benson, executive director of the Global Climate and Energy Project (GCEP) and professor of energy resources engineering: ”But the idea that we can take fossil fuels out of the mix very quickly is unrealistic. We’re reliant on fossil fuels, and a good pathway is to find ways to use them that don’t create a problem for the climate.”

    Any money spent on research into carbon capture and sequestration would be far better spent on the energy supply side in developing solar PV and thermal energy conversion plants, as well as in improving national electricity grids, setting up offshore giant wind turbine farms, and developing a variety of photosynthesis-based fuel production strategies. On the energy demand side, we should be focusing on energy conservation, fossil fuel-free agriculture and industry, efficient technology, good housing, and so on. Carbon capture is nothing but fool’s gold.

  7. 107
    Jim Cripwell says:

    Ref 75. What about solar cycle 24 shows no signs of getting going? I agree we need the debate on different data sets for global temperature anomalies.

  8. 108
    Alexandre says:

    The debate has its usual heat here, but it´s good to see a debate over possible solutions. Thank you RC people.

    My non-scientific opinion: keep it simple. Grow trees, lots of them, cut them down, prevent them from decaying or releasing its carbon to the atmosphere- water, confinement, mummification, whatever.
    Then repeat the process growing new ones. Maybe fertilizing the soil with Terra Preta would give it an extra kick.

    Oh, and leave the natural forests alone.

  9. 109

    RE #96, I know just the plant/tree for carbon capture, at least for tropical, subtropical, and arid places that don’t get killing frosts (at least not more than once in 5 or 10 years). It is the moringa tree. The following site has a great PowerPoint on it (& you can google for more sites) –

    We have them growing in our back yard in S. Texas (they are originally from India). They shoot up to 20 to 30 feet or more within a few years. We keep cutting them back so the fruits (drumsticks) won’t be so high, and we plant the branches, which shoot up to big trees in a few years. The leaves can also be eaten as spinach, and they increase milk production in lactating mothers and cows. The leaves and fruit are extremely nutritious, plus I think oil from the seeds can be used as biofuel (they are experimenting on it), and the seed pods and other parts can be used as cellulose biofuel.

    My husband doesn’t have the heart to throw away the pruned branches and has kept planting them, so we’re going to have a back yard forest after some time. We did have a killing frost a few years back, and the trees died down, but then sprang back up 20-30 feet within a few years. It grows in poor soil, drought conditions, or swampy conditions. Can be intercropped with other trees and plants, and doesn’t take up much space, since it grows straight up.

    I consider it one among many many many solutions to global warming (& world hunger).

    First principle is reduce (through energy/resource conservation/efficiency & good old “just reduce” on the non-essentials), then reuse, then recycle & buy recycled, then use alt energy, and if you have a bit of land in a warm enough area, plant moringa trees. Meanwhile the air-capture folks should be in full swing doing their part, as well. We need all these solutions and many more that might be thought up if we had an atmosphere conducive to eco-innovation.

    Anyone else here know about the moringa tree?

  10. 110

    #75 GlenFergus: in the meantime this page at the UK met office may be of some help.

    There are already claims out there that the temperature trend has flattened or even gone down. If you do a linear regression on Jan 2001-Feb 2008 of HadCRUT3 for example the trend is slightly down but the correlation coefficient is something like 0.05 which is not far off random.

    All you can really say about such a short period is that natural variability overwhelms the long-term trend, which remains up.

    If an article is written could I suggest something like “What if you can type into a spreadsheet but are a scientific illiterate?” Maybe a bit too confronting…

    Paul Dietz #91: Interesting idea, getting the carbon out of the sea. Given the concerns about ocean acidification (more correctly, becoming less alkaline) this could be a nice idea. Attack one of the more serious problems directly.

    Harold Ford #96: Plants are good at capturing carbon but the problem is that we are extending them beyond their design limits already (recalling that eras when CO_2 was higher were on a geological timescale away from now, i.e., evolution had time to optimize plants to the new environment). Plants are generally not CO_2 limited, otherwise they would be handling the problem already. If the problem persists of course there will be a shakedown (aka mass extinction event) where the plants better adapted to higher CO_2 will eventually dominate. Some of the plants which don’t like higher CO_2 include grain crops (from memory, maize/corn is one; wheat and rice can use more CO_2). Your idea may have some merit except that increased CO_2 is not the only variable, so is climate change. This could radically reduce areas of viable farm land, so converting the necessary big areas over to growing a weed would be problematic. Find something that thrives in the oceans on high carbon, and dies back and sinks to the bottom when carbon levels drop, and you may have a solution — thus nearly tying together your idea and Paul Dietz’s.

    Don’t confine your thinking to the macroscopic: some bacteria are photosynthesizers, and bacteria did the initial job of oxygenating the atmosphere. Some interesting stuff in Science Daily on how that became possible.

    Any comment from the real climate scientists? Could any of this work?

  11. 111
    Ferris says:

    #55 David Benson says: “Biochar makes a most useful soil amendment. But about half of the carbon returns to the active carbon cycle with a few years. Moreover, the storage time of the remainder is unknown.”

    David, as long as the soil is not disturbed, black carbon is very stable within the soil. Also, the storage time is very well known. In particular, the black carbon contained in the Amazonian Dark Earth’s, because of the particle size, is very stable (on the order of thousands of years).

    Even the black carbon produced from the burning of the tallgrass prairie’s here in the U.S. is very stable, despite the fact that it’s easily oxidized because of it’s small particle size.

    For a much more meaningfull discussion of the importance of black carbon in agriculture go here:

    #110 Philip Machanick says: “Some of the plants which don’t like higher CO_2 include grain crops (from memory, maize/corn is one; wheat and rice can use more CO_2)”

    Philip, this statement is not true. Corn production will increase as CO2 concentrations increase, just not as much as wheat and rice.

  12. 112
    Chuck Booth says:

    Re # 70 DBrown “Is this a joke?”

    Apparently not:

    A Guide to CO2 Sequestration
    Klaus S. Lackner
    Science 13 June 2003: Vol. 300. no. 5626, pp. 1677 – 1678

    Carbon capture and storage (or sequestration) is receiving increasing attention as one tool for reducing carbon dioxide concentrations in the atmosphere. In his Perspective, Lackner discusses the advantages and disadvantages of different methods of carbon sequestration. He advises against sequestration in environmentally active carbon pools such as the oceans, because it may merely trade one environmental problem for another. Better sequestration options include underground injection and (possibly underground) neutralization. Taking into account carbon capture, transport, and storage, the author concludes that in the short and medium term, sequestration would almost certainly be cheaper than a full transition to nuclear, wind, or solar energy.

  13. 113
    Chuck Booth says:

    Re # 63 JCH (and #71 Jim Galasyn’s response)

    As Jim suggested, sequestering CO2 in the deep ocean is not such a great idea:

    Potential Impacts of CO2 Injection on Deep-Sea Biota
    Brad A. Seibel and Patrick J. Walsh
    Science 12 October 2001: Vol. 294. no. 5541, pp. 319 – 320

    Efforts to reduce carbon dioxide emissions are increasingly looking to the oceans, either through iron fertilization programs …or through CO2 injection into the deep sea. In their Perspective, Seibel and Walsh investigate how such deep-sea disposal may affect organisms that live in these environments. They warn that even small perturbations in CO2 or pH may have important consequences for deep-sea ecosystems and for global biogeochemical cycles. Detailed studies into these effects are needed before the risks and benefits of deep-sea carbon storage can be assessed appropriately.

  14. 114
    JCH says:

    113. Re # 63 JCH (and #71 Jim Galasyn’s response), Chuck Booth

    Your concerns were why I asked if anybody was working on containerization. The articles I read were describing either injecting liquid CO2 into deep water, or sinking blocks of dry ice.

    This paper is more recent, and they are describing using the seabed as a container:

    Using the pressure and temperature to fence it in sounds interesting,

  15. 115
    Rod B says:

    I think I recall previous threads/posts here concluding that while we want and need all the trees, trees per se are not that marginally productive in picking up CO2, and planting more is neither timely nor effective. My old calculations said an average tree will absorb and sequester (for now) about 1100 kg of CO2 over roughly 30 years. [Ballpark figure, as there is considerable variability among species of both amount (600 – 1500 KG or more) and time (15 – 100 years)] Four hundred of these trees in a hectare (one every 25 sq. meters) would pick up the CO2 exhaust from 12 vehicles driving 15,000 miles per year each for five years getting 18MPG. Amplified by the 5-year output to 30-year absorption rate (would it ever catch up with the emissions?) or not, this seems like a gazillion trees have to be planted to make a dent.

    Lynn’s moringa trees seem pretty good. And it’s true (we suspect) that a goozillion bacteria had a large macro effect as Philip points out. I always thought the very fast growing with very fast plant metabolism (eating CO2) hemp might be good — one could use the fibers for cloth and paper and maybe get long-term sequestering; still probably couldn’t smoke the other parts, though. None-the-less all seem like drops in the vat.

  16. 116
    Jerry Toman says:

    Ultimately, this is about “allocation of resources”. It doesn’t make sense at this point in time to invest in “air capture” as long as we put CO2 into the air from sources of far higher concentrations. The one exception is effort expended in preventing forests which now store carbon from becoming “biofuel plantations”.

    If we use our resources to extract Convective Available Potential Energy from the troposphere instead, this will allow us to phase out fossil fuels by 2020. This will take only a minimal investment and a couple of years of effort dedicated to development of the Atmospheric Vortex Engine. (

    6000 times more CAPE is dissipated irreversibly than the rate at which humans produce and consume mechanical (electric) energy via fossil and nuclear fuels.

    Meanwhile geothermal and waste heat (including warm seawater) can be used to supplement the CAPE derived from the troposphere and renewed by the sun each day.

  17. 117

    Re #94 Kiashu:

    Martin at comment #40, liquid CO2’s density depends on pressure and temperature, but is usually much less than the solid form.

    Actually it’s around 1000 g/litre (only slightly pressure dependent), so multiply my figures with 1.6. Still reasonable. Supercritical is a different thing.

    BTW you are accusing a large number of honest, competent and hard working scientists and technologists of being involved in “a crock”. Looking at your informal article, I don’t see much to match that professionalism. I don’t know about you, but if I were one of those folks, I would have a problem with your attitude… please help to keep this forum minimally civilized.

  18. 118

    Re #104 Phillip Shaw: WordPress has the hateful habit of spam filtering on parts of words. Like “special-ist” containing the blue pills we all love to hate :-)

    Just put hyphens in the problem words.

  19. 119
    Nick Gotts says:

    RE #106 [Ike Solem] “There is literally no practical way to capture carbon from coal combustion. As the author points out:

    3) The best estimates for the energy consumption of AIr Capture is 350 kJ/mol CO2. I think we can get that down to 250. The heat released from coal is 400 kJ/mol CO2 with all other fuels higher owing to the hydrogen present. While not super efficient, we regularly accept only 35% conversion of coal to electricity.

    Practically, what that means is that we would have to build a massive new facility next to each coal-fired power plant on Earth, which would be dedicated to air capture, and which would consume, according to best estimates, 87.5% of the energy produced by the coal fired power plant, but, considering process inefficiencies (i.e. that 35% coal-to-electricity conversion), you’d be lucky to break even.”

    Ike, this is nonsense. What is proposed for CCS from power stations is NOT air capture.

  20. 120
    pete best says:

    Re #106. Ike, you seem very knowledgable on the subject but can you tell me your relevant qualifications in the field of carbon capture and climate science in general. Are you a interested layman or a scientific professional.

    I ask because the royal society in the UK has written to the UK Government asking that any new coal fired power stations have CCS fitted and hence they must think the technology is viable. However you do not. Who is right?

  21. 121
    C L says:

    Re #108/9.

    It seems to me that there is a fundamental philosophical distinction to be made between natural approaches to the problem (trees) and technological approaches (manufactured gadgets to scrub air). Natural systems produced the relative equilibrium and harmony that we found when we evolved.
    Technologies are what has got us into this present mess.

    Over-simply put, if you’ve got a problem of long grass around your house, you can either buy a noisy red mower to annoy your neighbours. You’ll have to earn the money to buy it, and for more expense for fuel and parts and maintenance, the manufacturers overheads and advertising, employees pension schemes, shareholders profits, and you’re tied to all the factories that make the bits, refineries, and the shipping networks, the whole rigmarole of international commerce, all of which presently rely on fossil fuels and cause pollution, etc. Then, with planned obsolescence, it’ll break and you’re forced to repeat.
    Or, alternatively, you can get something like rabbits, or sheep, or chickens, or geese, that’ll eat the grass, reproduce themselves, and produce food and fertilizer as a handy by product.

    I would certainly always be in favour of the latter eco-friendly approach. However, seems to me that we are now in such a global mess and so pressed for time, that all potential good ideas need to be considered, ( even if they look ugly, like nuclear power). There are plenty of them. People are extremely ingenious. The problems appear at the implementation stage. I can just imagine some scam merchant taking up the suggestion of moringa trees and raising funds to buy land, and then they’ll go and wreck some precious swamp with diverse rare species, or cut down ancient woodland, or whatever, and cause much more harm than good. The sort of stupidity that has followed from the misconceived biofuels fiasco is so typical. Anyone remember the East African ground nut scheme ?

    Farmers generally think of their crop yields in terms of land area. They need to think about how they can utilise the other dimension; upwards, with trees and climbers, downwards, building soil depth which acts as a storage for CO2 and water. Unfortunately, agribusiness thinks in terms of large scale monoculture to maximize efficiencies. I think it has been established that maximum diversity makes for maximum resilience in the face of climate perturbations. Put simply, if a thousand acres of potatoes is hit by drought and disease, you’re left with bare soil which blows or washes away. If the same thousand acres is covered by ancient woodland, with tens of thousands of species, it can easily cope with extremes. The field of potatoes is probably a net contributor to Global Warming, whilst the oldgrowth forest is one of the micro-units which created the previous stability we enjoyed.

    If climate change is very fast, the forests which have evolved to suit particular soil type and local conditions will want to move, to follow the thermocline. They can do this naturally, but it’s rather slow. a few miles a year. Human intervention might help, but usually there will be impassable obstacles, cities, mountain ranges, etc.

    Another issue is peat. I believe it’s correct that there is more CO2/methane locked in the UK peatbogs than in all the trees in Europe. How do we conserve peatbogs ? At the moment they are mined for garden compost. If the weather becomes drier, they will release their CO2. Seems to me always preferable to put money into trying to save the natural systems that do the work for free, (like sphagnum moss that’s fixing CO2 while we sleep in our beds), than put money into new technological gadgets. Seems to me that these start ups with a cunning new idea don’t ever do proper carbon accounting, in that they leave out all the associated inputs go along with the enterprise. Bit like folks who say they’ve planted a tree to compensate for an air flight, and think they’re ‘being responsible’ and virtuous. But what about all the hundreds of previous flights over decades ? each of us is responsible for the whole legacy we leave to the future generation. People on this site like to follow scientific logic. Logically, the best answer must be to leave all the coal and oil where it is, at least until we can sort out the CO2 problems. I’m not at all optimistic. I see almost everything that almost everyone is doing is pushing in the wrong direction, despite the efforts of a heroic minority. The real fundamental problem is human nature and politics, and there’s no techno-fix for that.

  22. 122
    DBrown says:

    Relative to my original post (#70) there seems to be some confusion, so I wish to clarify.

    First, my post was not totally serious but was, in a superficial way, only pointing out that the cost effective extraction of atmospheric CO2 as the original author claimed by chemical removal of the gas from the atmosphere is far too energy intensive to be worthwhile.

    A few people have posted that plants already do this and they feel that this revelation on their part is significant and (I assume) that this somehow validates chemical/mechanical methods proposed in the original article. All I can say is please explain how this relates to author’s process?

    As many have posted, capture at the point sources is far more feasible but then other issues come into play (energy production, storage, transport costs, etc) and need to be addressed in a serious, technical manner, not the silly manner the original author exploited.

    As for post #73, comparing the possibility of atmospheric processing to total world population the writer is misguided – last I checked, respiration by people does not process CO2 from the atmosphere into any storable form. Their claim that this proves the idea of atmospheric collection is feasible is simply ludicrous.

    As for using algae in the oceans post #113 says it all.

    To address the idea of land surface processing using plants, such a massive program would be highly complex but a superficial look does not appear promising.
    Relative to areas that fresh water and sun are readily available, most the tree’s that used to do this have been removed and the land is being exploited by humans for very minor purpose like food production, and habitat similar uses.

    As for using deserts for algae systems (lots of free solar energy, open land), the creation of vast pond systems would require large inputs of energy (digging/excavation, processing and construction equipment, water pumping/delivery systems, aeration systems, and related support facilities to name the obvious issues) and even if the algae can be converted into fuel (energy content, and transport to market costs?) in order to process sufficient CO2 from the atmosphere to radically affect CO2 climate warming would be highly doubtful (if you think otherwise, please reference a peer reviewed paper showing otherwise. Hand waving is not too useful.)

    Relative to power sources for atmospheric capture, some have suggested thorium power plants. I know next to nothing about thorium plants and can only say that to the best of my knowledge, no commercial plants have or ever have been constructed and that would appear to indicate that this is not (currently) viable. Someone knowledgeable in the field should address this issue.
    Breeder reactors are a whole other story and can be very dangerous despite the posts by some that indicate that this belief is not based on facts.
    A few minor points: the one US commercial breeder plant (Fermi plant, outside Detroit) had a major meltdown and more by luck, did not undergo a nuclear fission explosion. If it had, the city could very well have been destroyed. Breeding nuclear fuel requires very extensive chemical processing that creates extremely radioactive and large amounts of nuclear waste that must be handled, transported and stored. Also, these plants can be used to manufacture material for atomic bombs – hardly what we want every country in the world to be doing.
    American designed high pressure boiling water reactors are very difficult to safely operate without massive, complex, highly costly and failure prone systems and while no deaths have occurred in this country from numerous nuclear reactor accidents, I understand people’s very rational fear of these plants.
    The Canadian plants (heavy water, natural uranium fuel) are highly safe and compared to US plants, much more inexpensive but they have a problem: these plants require high quality natural uranium and if a lot of such plants are built, getting enough fuel could be a major problem.

    In any case, wasting such power plant energy production on CO2 capture is worse than foolish, it is irresponsible. Any none CO2 based energy source should be used to supply power to support people’s direct survival, not diverted in an inefficient manner to capture CO2.

  23. 123
    Ray Ladbury says:

    Nick Gotts, re: dirty bombs. The main value of a dirty bomb as a terrorist weapon derives more from irrational fear than actual damage–and in any case, Uranium and Thorium would make really lousy dirty bombs due th their high density and the nature of their decays. The Th fuel cycle is more desirable in part because it is more difficult to weaponize the byproducts than Uranium or even Plutonium.
    There was a pretty good article a couple of years back in American Scientist on the process. I do not discount the difficulties associated with nuclear power–storage of wastes and proliferation are not trivial problems. However, in some ways, the waste problem is easier than it would be for, say, a coal plant precisely because the pollution is from a point source. Nuclear power would not be my first choice as an alternative energy source, but if it came to a choice between nuclear and coal, I think the overall threats from nuclear are easier to manage than the climate threat stemming from coal. CCS could change this balance, but that remains to be seen. I am reluctant to prejudge the outcome, since I view the climate as the main threat facing the continued viability of human civilization over the next century–well maybe second to human stupidity. Cheers, Ray

  24. 124
    John Laumer says:

    Performing a life cycle inventory on any of the proposed technologies for capture is straightfoward, and has already been done for production of the Kraft process inputs. So there is no need really to speculate. Someone at DOE needs to get the assignment to combine the information and off we go.

    An earlier commenter brought up serpentine rock as a carbon sequestration medium. See this excerpt from a post I wrote for regarding some limitations.

    “…Serpentine rock, as Mg3Si2O5(OH)4,is the California State Rock, and “is found only in areas where oceanic crust is subducted and then pushed up again along fault zones. Worldwide, Serpentine is sporadic in distribution and high in heavy metals, creating rare plant communities on its soils”.

    One obvious risk management ‘driver’ is that that serpentine barrens often support rare and/or endangered plant communities. Further, that benefaction and processing of the serpentine rock will produce heavy metal residues; and, it would be essential that these materials be turned into co-products or that magnesium suppliers ensure they are properly disposed of. Both reasons underscore the need to base the system design on a recycling paradigm.”

  25. 125
    Nick Gotts says:

    Re #123 Thanks Ray – I’ll see if I can find that AmSci article on dirty bombs. But as I understand it, while U233 is more difficult to handle than U235 due to its higher radioactivity, it can still be made into nuclear weapons. I guess the question is – would you want it freely traded to anyone with the money? If not, we’d do best to minimize how much of it there is.

  26. 126
    Kiashu says:

    Martin at comment #117 writes that “BTW you are accusing a large number of honest, competent and hard working scientists and technologists of being involved in “a crock”.”

    That’s the appeal to authority logical fallacy.

    The problem with that is that equally honest, competent and hard working scientists say that CCS is not likely to ever be a significant mitigator of climate change, and that the best thing to do is just burn less stuff.

    Tim Flannery’s one example of an honest, competent and hard working scientist who thinks CCS is a crock. I mean, this isn’t like climate change, where it’s pretty obvious that the “scientists” denying it used to be working for the tobacco industry and are many smaller in number than the scientists arguing the data support climate change. With climate change if we want to do an appeal to authority, well 1,000 or more to 1 seems pretty good.

    With CCS, it’s rather less than that in favour.

    That’s the problem with the argument from authority; what do you do when two equal authorities disagree?

    Consider for example uranium mining on Navajo land in the US, gristmill mentions the LA Times doing a series on it recently. At the time a big swag of scientists – honest, competent and hard working – said it’d be completely safe for the Navajo. A few decades on and they’ve got animals born without eyes, double the pre-mining rate of cancer, and so on. Now a mining company wants to go back in and dig up some more uranium, and there’ll be a legal battle, where one lot of honest, competent and hard working scientists say it’s horrible and deadly, and another lot of honest, competent and hard working scientists say it’s all harmless.

    Just because an honest, competent and hard working scientist is involved does not mean it’s a good idea.

    All you’ve done is to take offence at my tone, and my temerity in daring to question that any honest, competent and hard working scientist could ever be wrong. You’ve not spoken to my substantive points:

    – liquefying the CO2 from coal-fired plants will require at least one-third the energy those coal-fired plants generate.
    — does this mean we’ll reduce our non-CO2-liquefying electricity consumption by one-third, or that we’ll build 50% more capacity?
    – CCS has not been fully successfully trialled anywhere.
    — the CO2 for enhanced oil and gas recovery came from industrial plants manufacturing it, not from coal-fired stations, cars, etc; so the capture technology is unproven and indeed largely untested and uninvented
    — CO2 injected has leaked in every site
    — CO2 injected into coal seams is designed to released CH4, a stronger greenhouse gas than CO2, and this too will leak; already 5-10% of the natural gas we use leaks before end use
    — CH4 generated from CO2 injections into coal seams will be burned, releasing more CO2, so this may not actually be a net sequestering of carbon; no calculations have been made public
    – how are we going to capture the carbon emissions from vehicles, deforestation, livestock, rice farming and so on?

    Further points, not mentioned in my article, would be the decades required for a rollout of such technologies, even assuming they could be made perfect without further research or effort. I look forward to projections from those sponsoring CCS showing that we could achieve substantive reductions in emissions as a result. But I’ve not seen those projections. No-one seems to have said, “it will take this long, cost this much and achieve so-and-so.”

    I look forward to a response to my substantive points. If they’re so unprofessional and stupid, it really shouldn’t be difficult. Robert in comment #34, for example, made a comment about the large volumes available, he easily knocked me down on that.

    I mean, if I come in with something like, “oh but what about solar forcing?” then I’ll be demolished in moments, because I’m so plainly wrong. So, show me how I’m wrong in this.

  27. 127
    pat n says:

    re #21 Secondary effects from more nuclear power plants will add to what “Nature will do the job for us” … and greatly reduce AGHG emissions in the long term.

  28. 128
    Kiashu says:

    Incidentally, Vaclav Smil, (an alumnus of Penn State), wrote in Energy at the Crossroads [pdf], that,

    “A key comparison illustrates the daunting scale of the challenge. In 2005
    worldwide CO2 emissions amounted to nearly 28 Gt; even if were to set out only a modest goal of sequestering just 10% of this volume we would have to put away annually about 6 Gm3 (assuming that all of the gas is compressed at least to its critical point where its density is 0.47 g/mL). The current extraction of crude oil (nearly 4 Gt in 2005) translates to less than 5 Gm3. Sequestering a mere 1/10 of today’s global CO2 emissions (focus – they just look at one little bit. I mean, that’s how science is done. Nobody measures or tests or experiments on everything. They just pick a bit that interests them and have a look at that.

    So in doing that, it can be easy for them to miss the big picture. Busily focused on measuring the rates of CO2 adsorption in anthracite, they might not ask themselves, “okay, if this all works well, how much of the coal-fired plant’s power are we going to need to deal with its CO2?” It probably won’t even occur to them.

    Likewise, it does not seem to have occurred to anyone except Smil just how much infrastructure a worldwide sequestration project might need. And it turns out it’s quite a lot, and it’s not really plausible that we’ll build it all.

    He says further, and I largely agree,

    “I must hasten to add that underground CO2 sequestration in the service
    of secondary oil recovery is most desirable, as is any form of plant-bound
    sequestration, ranging from a gradual build-up of soil organic matter to
    massive planting of trees. But beyond these highly desirable actions the stress must be on reducing the emissions, not hiding them in an uncertain and costly manner.” [p.21, my emphasis]

    I don’t agree that pumping out more oil is desirable, but if it’s going to be pumped out anyway, we may as well pump its pollutants back in.

    “The obvious question is why it should be even attempted given the fact
    that a 10% reduction in CO2 emissions could be achieved by several more
    rational, mature and readily available adjustments. […] Of course, this suggestion is always met with derision and the chances of such a shift are judged to be utterly impossible.” [p.21]

    Of course if people know of techniques for sequestration of the CO2 using substantially less infrastructure than Smil suggests, I’d certainly be interested in hearing of them, and I’m sure a few large oil, coal and gas companies would pay good money for those ideas.

  29. 129

    RE #115 & “Four hundred of these trees in a hectare (one every 25 sq. meters) would pick up the CO2 exhaust from 12 vehicles driving 15,000 miles per year each for five years getting 18MPG” & “all seem like drops in the vat.”

    Yes, it’s an uphill struggle, but never give up, never surrender. First of all, men & women, we need to stop driving our cars 15,000 miles a year (unless we’re traveling salespersons). We need to move closer to work/shops/school. We need to take more public transportation, bicycle, and walk (and smell the roses along the way, & reduce our heart disease, cancer, and diabetes, etc.).

    We need to get much more than 18 mpg — we need those plug-in hybrids, live within 5 miles of work (preferrably one, so we can walk), have wind or solar electricity & drive on the wind/sun (my 100% wind-powered GreenMountain electicity is actually cheaper than coal/gas powered electricity). We need to turn off our motor in drive-thrus, keep tires inflated, avoid jack-rabbit starts & reckless driving.

    And we need to plant more trees. And do air-capture.


    I know taking a hanky for drying hands in public restrooms is less than the proverbiable drop in the ocean, but drops add up, even half-drops. If everyone reduced just one little candle’s worth of of CO2E whenever possible/feasible, what a cool world this would be.

  30. 130

    OT, but just found out about this new TV series in England, THE ELEVENTH HOUR, a present-day investigative thriller about a retired scientist assigned to investigate scientific issues — which involve powerful interests out to do bad. And it has an episode about global warming!!


    Be sure to view the preview & synopsis of Episode 3, “KRYPTOS,” which is about a climate scientist who says he has proof of some imminent climate catastrophe, and is claiming people are out to do him in….they think he’s paranoid, until he goes missing….

    Maybe RC scientists can view it (those who might have access to it) and give their scientific assessment.

    Hope they bring the series over here to the U.S.

  31. 131
    David B. Benson says:

    Ferris (111) — I encourage you to also read the recent report summarizing what is known about biochar, especially with regard to lifetime of the carbon in the ground. It is a .pdf file accessable via this link:

  32. 132

    Thomas said,

    Go back to …


    comment #53. Basically what is needed is to simply crush a bunch of rocks of the right kind, and spread then out to a depth shallow enough that the CO2 is absorbed within a few decades. The problem is that the quantity would need to be similar to the volume of oil we use per year (3-4 km**3), I don’t know how feasible this is, clearly it would mean disturbance of many square KM**2 per year of desert.

    Each 100 gigatonnes of legacy CO2 in the atmosphere would convert to a few hundred km^3 of dust. If this were deposited over tens of millions of km^2 of dry desert, or hundreds of millions of km^2 of a wet desert such as the southern ocean, whose CO2 sponginess you may recall has recently been in the news as getting tired, it would be unobtrusive. Remember, the accumulation would be over a decade or so. I said more about this here, although at that time I didn’t yet know about olivine’s goodness, so thank you for that.

    The main energy cost are the explosives for breaking up the rock, and to push it around. Chemistry, and time do the rest for free.

    For the comminution of the olivine or serpentinite you want to use mostly electricity, not explosives. I’m pretty sure primary energy to electricity is a much lower-loss conversion than primary energy to explosives, and electric ore crushers had become very efficient by the early 1990s. (The uranium in one piece of average continental surface stuff, if fed to CANDU reactors, would enable those crushers to crush, or “comminute”, five equally heavy pieces.)

    (Postings have individual URLs that are hidden in the date-and-time line under the poster’s nym or pseudonym. Try the right mouse button on one and you should find it possible to pluck the URL and put in into a link, rather than telling people to search.)

  33. 133
    Phillip Shaw says:

    Re #70 DBrown et al:

    There is a technology that I haven’t seen discussed much which demonstrates the feasibility of capturing CO2 from the air. Industrial Air Separation Units (ASUs) have been around for decades and are a mature and robust technology which may be worth investigating. The basic process is straightforward: air, either ambi-ent air or a CO2 enriched gas, is compressed and cooled to condense and remove its moisture. The dry gas is further compressed and cooled until the CO2 condenses and can be drawn off for sequestration. For industrial purposes additional stages are used to produce liquid nitrogen and liquid oxygen, but for this discussion we don’t need to go into that. Once the CO2 is removed the air is released. There are several nice aspects to the ASU process. One is that the only ‘waste’ product is reasonably pure water. Another is that a significant portion of the energy spent compressing and cooling the gas stream can be recovered by expanding the CO2-depleted air through a turbine to compress and cool the incoming air.

    I envision ASU technology being incorporated into solar powered CO2 capture units designed to be efficiently mass-produced. Thousands of these could be placed in desert areas such as western Australia or western North America and the water they produce could be used to convert desert into arable acreage. Initially the plant yields would be low due to the poor desert soil, but by converting the initial growth into biochar and plowing it back under to improve the soil the land would become more productive. Ideally, this iterative cycle would produce arable land for crops and/or biofuel feedstock. I don’t believe that tree farms are out of the question either. The plant material grown, and the carbon sequestered in the biochar, increase the overall efficiency of this idea. I understand that the CO2 collected would still have to be sequestered but that is true of all carbon capture concepts.

    My thanks to Martin Vermeer for helping me navigate the WordPress spam filter. Would you believe the problem word was ambi-ent?

  34. 134
    Jim Bullis says:

    Re 74 Edward Greisch and 29
    In the scheme I am suggesting, the waste heat from very small engines in very efficient cars (about 12 horsepower) would power electric generators that would charge car batteries and feed power to the grid. Thus, the car and the house are arranged for very efficient cogeneration. There is very little equipment cost for plumbing connections that would enable heat transfer to the household and would also enable transfer of natural gas to the car. The key difference from the status quo is the size of the engine and generator in the car. The PRIUS engine is probably too big to be “appropriately sized” for this kind of operation. However, if a new type of high efficiency vehicle were to come about, a very large energy saving could come about.

  35. 135
    Ike Solem says:

    Nick and pete, I think the car example is a good one. If someone can build a car that has a carbon capture system attached to the tailpipe that safely removes the carbon and stores it in some stable form as you drive down the road, why haven’t they? Where’s the working prototype?

    Here’s the background from an article that promotes carbon capture and sequestration, written by a very prominent Harvard geochemist: Daniel P. Schrag, et al. Preparing to Capture Carbon, Science 315, 812 (2007):

    “In 2003, President Bush announced a commitment to FutureGen, a DOE project to build a zero-emission coal gasification plant that would capture and store all the CO2 it produced.

    FutureGen is an exciting step forward, but a single coal gasification plant that demonstrates carbon sequestration is unlikely to convince the world that carbon sequestration is the right strategy to reduce CO2 emissions. Moreover, a power plant operated by the government may fail to convince power companies that the costs of sequestration are well determined. . .

    Luckily, FutureGen has competitors. British Petroleum (BP), in cooperation with General Electric, plans to build two electricity-generating plants, one in Scotland and one in California, that would sequester CO2 with enhanced oil recovery. Xcel Energy has also made a commitment to build a coal gasification plant with sequestration. And more projects may soon be announced as companies begin to view legislation controlling CO2 emissions as a political inevitability.

    So, what are the problems?

    One is that a lot of this work is being done within the murky “public-private sector”, making it very hard for someone to independently evaluate it. However, since FutureGen was supposed to be state-of-the-art in terms of carbon capture and zero-emissions coal power, the flagship example, it’s worth looking at.

    FutureGen was to use an Integrated Gasification Combined Cycle (IGCC) power plant. This is simply an efficient two turbine power plant – a gas and a steam turbine – that uses gas derived from a thermal cracking process carried out under low-oxygen conditions (DOE). IGCC plants are also at the heart of biomass gasification strategies (as per Germany).

    The problem is the capture end. In the case of biomass, the carbon came out of the atmosphere when the plant grew, and is returned when the biomass is burned. For coal, the stream of combustion products has to be captured and sequestered – and coal is generally loaded up with sulfur, arsenic, mercury and other elements that have to be removed and disposed of as well. There are no such problems with biomass, and no need for carbon capture – just a limited supply.

    FutureGen intended to capture the carbon produced from coal gasification before the syngas mixture was burned (syngas is CO +H2). This was intended to produce a pure, easy-to-capture stream of carbon monoxide…a deadly poison – and a pure stream of hydrogen for fuel use.

    It’s actually hard to find the details of what went wrong with FutureGen and led to the project’s cancellation. There are no published papers on it, and apparently no independent peer review either. Here’s one blurb: U.S. Dumps FutureGen Project, Fri Mar 2008.

    Now, carbon capture proponents have fallen back on promoting capture after the coal gas is burned, also in IGCC plants. The CO2 is more dilute, so more energy will have to be used to remove it. No one is going to outfit existing coal-fired power plants with carbon capture systems, because that would suck up almost all the power produced by the coal plant – they are proposing to build more IGCC carbon-capture plants, when they have yet to demonstrate that the technology can work at anything near the proposed scale- 20 lbs of coal per person per day in U.S., adding up to a billion tons of coal per year, resulting in the need to store about 3 billion tons of CO2 – per year – in the U.S. alone. The notion is ridiculous.

    For a more complete critique, see this article.

    Finally, we already have the means to replace all coal-fired power stations using wind(Wind power leads British push to sustainability) and solar (Solar Thermal Power Could Supply Over 90 percent Of US Grid), and energy storage technologies (New NaS battery packs powerful punch). Biofuels and nuclear can also be carbon-neutral options, but on a case-by-case basis. That’s where any new investment should go.

    Realistically, we should ban all new coal-fired power plant construction, and as they existing ones become decrepit, they should be replaced with clean energy systems.

  36. 136
    David B. Benson says:

    Kiashu (136) wrote “CH4 generated from CO2 injections into coal seams will be burned, releasing more CO2, so this may not actually be a net sequestering of carbon; no calculations have been made public”. Test results are on the web: coal seams naturally have some methane chemically bound to the coal. The introduced CO2 displaces the methane, as it binds tighter. The ratio is between 2 and 3 molecules of CO2 for every molecule of CH4 displaced. Since the expressed methane can be captured for introduction into the natural gas network, the result is a net gain of between one and two.

    As best I can make out, nobody is pushing this strategy. Sequestration of CO2 in deep saline formations offers, it appears, a similar chemical affinity and without any methane being expressed (it is currently thought).

  37. 137
    DBrown says:

    Phillip Shaw,
    Your claim that CO2 can be captured from the atmosphere in a cost effective (energy) manner by simple compression is not possible. I will not waste my time to give you the details but here is a start: PV = nRT (the standard gas equation). Learn some basic physics and please figure out the pressure for your self in order to liquefy CO2 and determine how much CO2 (mg) you will get per cubic liter of air (CO2 @ 0.038%) and a PV chart.
    You simply embarrass yourself when you attempt to talk like you know something when you do not even offer the simplest thermodynamic calculation – as for getting ‘waste’ water, please, the amount obtained is only what’s already in the atmosphere (read about humidity and how much water is generally present in a desert atmosphere on a normal day) and that quantity will never be significant enough to provide water for a desert facility in a cost effective manner to grown large number of plants – it would be far easier to pump ground water.
    Your idea that you can capture a significant amount of energy by re-expanding the gas is middle school reasoning and you are showing that you do not understand even science on that level – the Carnot cycle can be used to determine the efficiency of any heat based system and doing what you claim is nonsense – high temperature stream turbines (i.e. coal power plants operating at the temperature difference of over a 1000 C can, maybe reach a 38% conversion efficiency. And you think a 200 C or so differential is efficient enough to make a significant contribution to a compression process for energy recovery? Your ignorance is extreme and you need to learn some physical chemistry before you make any more technical claims about a process being ‘economical’.

  38. 138
    Phil Scadden says:

    “As best I can make out, nobody is pushing this strategy. Sequestration of CO2 in deep saline formations offers, it appears, a similar chemical affinity and without any methane being expressed (it is currently thought).”

    Lots of people looking at (including us). While the gains arent as high the CH4 recovery is a partial cost offset at well.

    NZ govt at moment has a moratorium on any state-owned company building any new thermal generation unless there is CO2 sequestered or offset so a lot of interest. The issue though is that the size of reservoirs are small compared to deleted gas reservoirs.

  39. 139
    Jim Galasyn says:

    Re 137: I, for one, welcome our new chemist overlords. I’d like to remind them that as a trusted TV personality, I can be helpful in rounding up others to toil in their underground carbon mines.

  40. 140
    Erich J. Knight says:

    The co-benefits of Biochar must also be considered beyond Bio-fuel gains; 3X fertility,17% less water use, Massive fungi (Glomalin) and wee-beastie microbes to worms, are sequestered carbon adding to that of the Biochar which in Terra Preta soils has C13 tested to 7000 years.

    Dr. Lukas reports 10X N2O soil emission reductions:

    Beyond Zero Emissions interviews Dr Lukas Van Zweitan senior research scientist of the NSW Department of Primary Industries (DPI). Who is working hand-on with soil research focusing on Bio Char (Terra Preta de Indio / Agri Char)

    “we’ve found with some of the biochars in that we’ve had very, very significant reductions in nitrous oxide emissions from the soil; between five- and ten-fold reductions in nitrous oxide emissions.”…ls-zero-carbon


  41. 141
    Robert says:

    Re 126: You really don’t understand CO2 capture. Several points:

    1. CO2 capture is currently practiced at the Dakota Gasification Company SNG (substitute natural gas) plant in North Dakota. CO2 is recovered and pipelined I believe over 100 miles to Wyoming for use in an oil-field miscible flood. So don’t say it hasn’t been proven.

    2. The parasitic power consumption and loss of energy due shifting CO and H20 to CO2 and H2 is 84 MW for a 640 MW IGCC plant using GE’s gasifier design, or 13% (see NETL’s website This case assumes 90% CO2 capture, and includes compression costs (2200 psig) to transport the CO2 50 miles by pipeline.

    3. Oil companies do not get the majority of their CO2 from industrial plants, but from natural CO2-producing formations, such as Sheep mountain in Colorado. That CO2 is pipelined to the permian basin in Texas for a miscible flood, and they’ve been doing it for decades.

    Re 135: You say that futuregen would capture CO, a poisonous gas. Wrong, it would shift CO to CO2 and H2, and capture the CO2 while the shifted synthesis gas is at very high pressure, about 450 psig or so. This helps to minimize the size of the absorber, and reduces compression costs of the CO2 after recovery from the stripper.

    There is no problem with the feasibility of futuregen; the issue is economics. Until carbon capture is mandated, no one is going to waste their money on it, pure and simple. Nothing murky or sinister….

    I have over 30 years in the chemical industry, and have been investigating gasification for about four years for my company. It is a technology practiced widely to produce chemicals; e.g., Eastman uses it in their Tennessee plant to make acetic acid, and derivatives such as tylenol. Pain relief from coal!

    The problem, once again, is that until there is a mandate, power plants will not move forward with this technology.

  42. 142
    Robert says:

    I forgot to mention once again the potential for gasification with CCS using biomass. Note that Nuon, a power company in the Netherlands, practices this today, using I believe up to 15% biomass mixed with coal. There is no reason this percentage could not be higher. This makes so much more sense then air capture of CO2. See my earlie post #76….

  43. 143
    Kiashu says:

    Nope, still didn’t work. I think I’ve figured out what did it, the “less than” sign is used in html, so… anyway, here’s the corrected quote, please delete my last post.

    “A key comparison illustrates the daunting scale of the challenge. In 2005 worldwide CO2 emissions amounted to nearly 28 Gt; even if were to set out only a modest goal of sequestering just 10% of this volume we would have to put away annually about 6 Gm3 (assuming that all of the gas is compressed at least to its critical point where its density is 0.47 g/mL). The current extraction of crude oil (nearly 4 Gt in 2005) translates to less than 5 Gm3. Sequestering a mere 1/10 of today’s global CO2 emissions (less than 3 Gt CO2) would thus call for putting in place an industry that would have to force underground every year the volume of compressed gas larger than or (with higher compression) equal to the volume of crude oil extracted globally by petroleum industry whose infrastructures and capacities have been put in place over a century of development. Needless to say, such a technical feat could not be accomplished within a single generation.”

  44. 144
    Phillip Shaw says:

    Re 137 dbrown:

    First let me say that the tone of your comment seemed a bit cranky . . . perhaps you should consider switching to decaf. Second, this is not the forum for flame wars.

    And the funny thing is, you’re wrong. ASUs are not a pipedream, they are commercially available today in a range of capacities. If you google “air separation unit” you should get more than 78,000 hits. Add “carbon capture” to your search terms and you’ll still get a thousand or so hits. Granted, most of the proposed carbon capture approaches that use ASUs use them to produce purified O2, but the principle is the same.

    You are correct that a tremendous amount of air would have to be processed to capture a meaningful amount of CO2. Nobody has claimed otherwise, so what’s your point? You’ve correctly pointed out that desert air contains little moisture but, again, nobody has claimed otherwise, so what’s your point? In many desert areas there is little or no groundwater to use, and what groundwater is available is often overcommitted to agricultural and municipal users. So however much water solar powered ASUs produced, it would be water available for growing biomass.

    The concept I put forward is just that – a concept. One which may, or may not, be practical and feasible. I can’t answer that question. It was put forward simply to stimulate discussion and alternative ways of looking at the problem of carbon capture. I believe that is what this thread is intended for. I really don’t see how your rudeness adds anything for anyone but yourself.

    And, no, I didn’t embarrass myself because I didn’t pretend to be more than I am. You, on the other hand, have much to be chagrined about.

  45. 145

    Re #126:

    Martin at comment #117 writes that “BTW you are accusing a large number of honest, competent and hard working scientists and technologists of being involved in “a crock”.”

    That’s the appeal to authority logical fallacy.

    No it is not. It is just what it appears to be, taking exception to insulting language.

    I see that you are now starting to address the substance of the matter. Why didn’t you start with that?

    – CCS has not been fully successfully trialled anywhere.

    Precisely. Any solution to the AGW problem will be a portfolio of “wedges”. Shouldn’t we give this one a chance too? (I used to be skeptical about CCS like you even up till recently, and you may still be right, but don’t you want to find out?)

  46. 146
    Chris Squire [UK] says:

    Use & l t; to get HTML to display ‘less than’. ‘As computer programmers might expect, “nop” means “no operation”, ie don’t do anything. It’s occasionally useful in programming, but I don’t know why they invented it for HTML; nevertheless it comes in handy for this situation. E.g.

    This is not displaying as intended. See: for a fuller discussion.

  47. 147
    pete best says:

    There are a lot of opinions and assumptions in these posts on CCS, Thorium nuclear plants, Algae CCS and Algae biofuels etc but also some very good posts and what look like good facts on CCS and Co2 sequestration in general.

    The porblem is that some think it feasible and point to existing plants that already CCS for enhanced oil recovery rather than burial under the ground. My issue us that each power plant is going to be different in regards to where CO2 will be pumped, the costs, and even the feasibility. Reading all of these posts just makes me more and more confused.

    Some people obviously know something about thermodynamics and spent hot gases, about the energy requirements of Co2 capture from the air or from exhaust or pre exhaust gases but there is no consensus here it would seem.

    Thorium power plants are viable but from what I have read not economically preferred due to Uranium being the preferred fuel as it is subsidised and there is a lot of vested interest in it.

    It looks like CCS is viable but FutureGen has been cancelled and as Ike points out in post #135 there is little actual technical data on why it has been cancelled but the costs seem to indicate something of its demise. The question is: enhanced oil recovery is one way of using spent Co2 gases and seems to demonstate that you can take a very hot gas and cool it, sequester the CO2 and use it to recover more oil from depleting fields. Does not this prove the viability of CCS at all?

    getting very worried now about it all.

  48. 148
    pete best says:

    Re #142 qand #76. Do you have any particular reason for not thinking that 000’s of scientists using the same methods and analyses as you do in your field of endeavour have got it completely wrong or are you of the opinion/knowledge that as yet the jury is still out or that they do as yet not have enough data to make the statements that the IPCC and GISS etc do?

    After all climate science is a mixture of physics, chemistry, biology, geology, astrophysics etc and hence is hightly quantitative and detailed.

    I would like an explanation of your position if you can find the time to reply?

  49. 149
    pete best says:

    Re #141, Robert, a great post and one that points to the fact that if all you have posted is true (hard to judge from an laymans perspective you understand but I have no reason to doubt you all the same) that it is economics that prevent CCS from becomming a reality and not any technical obstacles to be fair.

    is that a fair assessment of the situation. It is politically and economically undesireable at the present time due to the costs of implementation? If this is the case and it is eventually actively implemented, how long before a fully working CCS coal fired power plant could be tested. A decade ?

  50. 150
    Nick Gotts says:

    Re #135 Ike, don’t argue it with me, I’m no expert. Argue it with the IPCC: see their Special Report of Working Group III on CCS. I’m all in favour of renewables, energy efficiency and demand reduction; my main reason for supporting CCS research is that I just can’t see China and India leaving their cheap and abundant coal in the ground. I disagree that “the car example is a good one”, since to my knowledge, no-one has seriously suggested CCS on such a tiny scale. Scale makes a difference, you know. My original point was simply that you were posting rubbish because you hadn’t bothered to differentiate between the subject of the post – air capture – and CCS from power stations.