Wednesday, March 24, 2010

Friends of Earth UK's questionable support for chemical open air carbon capture

Maybe I'm biased because of Roger Pielke Jr.'s misrepresentations in favor of chemical air capture, but I was a little surprised at the partial thumb's up given by FOE UK to chemical capture.  Because they're sane they give priority to reducing emissions over geoengineering fantasies ("Mitigation has to be the priority for action, action far in excess of currently being considered by politicians is needed.").  Still, they give chemical capture some props, including favoring it over biomass power plus sequestration:

The use of large-scale afforestation, bio-char production and biomass carbon capture and storage have some limited carbon reduction potential but there are very significant land use issues associated with these. These geoengineering techniques could seriously compete with land needed to produce food (the quantity of land required varies hugely dependent on diet) and land for the protection of ecosystems. Until these land-use issues are better understood Friends of the Earth cannot support the use of large-scale afforestation, bio-char production and biomass carbon capture and storage.

Chemical air capture of carbon is the most promising carbon reduction option, although some research is still needed into safe storage sites. This is a very expensive option which is far more costly than mitigation. However rich countries have already far exceeded their fair share of “environmental space” through releasing far more than their fair share of carbon emissions over the last 200 years. If safe storage sites can be identified rich countries should carry out significant air capture of carbon, in additional to very significant cuts in emissions.

The problem with this analysis is the apples and oranges comparisons of costs.  Chemical capture can only be done at great cost per unit of carbon reduction, so FOE assumes that large costs are allowable for chemical capture but not for the biological techniques.  OTOH, if you assume you're allowed to spend the same amount on biomass or biochar, you can solve at least some of the problems that FOE identified with them.  At least you could provide incentives to use non-agricultural land for biomass production.  This might still produce pressure on natural habitat, but if we're assuming lots of money, there's ways to deal with that too, like paying for increased productivity on farmland instead.

Of course I'm just waving my hands at cost figures instead of crunching them, but that still puts me one step ahead of FOE.  Somebody needs to do the numbers.  Roger claimed to have done the numbers, but 1. his work generally raises doubts in my mind and I'm not going to spend time checking every citation to determine whether it says what he claims it says; 2. he only examines capture costs, not sequestration costs, transport, monitoring, technology development etc ("In this paper I explore some of the economic considerations associated with air capture of carbon dioxide, and do not address issues of storage, which are explored in depth elsewhere"); and 3. he does his own apples to oranges thing of comparing the partial costs of capture to full costs of mitigation in the Stern Report and IPCC (in part 4.1:  "If air capture technology could be implemented at [lowest rate cited by Roger], then the cost to stabilize emissions over the 21st century would be less than the Stern median estimate....The IPCC median value of 1.3% [of global GDP] is less than the costs air capture [sic] at $360 cost per ton of carbon, but almost three times the cost at $100 per ton.")

I hope FOE reconsiders its analysis sometime on an apples to apples basis.  I wouldn't rule out chemical capture, but it needs to considered realistically.


  1. Does it really matter whether the cost of air capture is 1.3% of global GDP or three times as much? Either way it of the same order as a year of typical income growth. What I find puzzling is that we would rather fry the planet, abandon our affluent lifestyle, or replace our natural environment with biofuel or biochar crops than postpone an increase in our standard of living for a year or so.

    If we are going to burn fossil fuel we need to capture and sequester the carbon dioxide produced and we need to start now, but there is currently no financial incentive to do so.

    In a recent Times Online live debate see

    85% voted that "Fossil fuel companies should be obliged to sequester an increasing fraction of the carbon content of the products they sell to avoid dangerous climate change".

    For details on why this proposal would be easier for all countries to agree to than cap and trade or carbon tax, how it would drive energy saving and renewables and how it would be implemented see my website at

    and my article at

    When fuel producers are obliged to place contracts for the capture and sequestration of a proportion of the carbon in their fuel, as I propose, I think there will be power companies and others from around the world competing to take their money. I hope we will be left wondering what all the fuss around cutting emissions was about.

  2. No objection from me, except that you can't sequester non-point sources of CO2 emissions like autos (not until we switch them to electrics).

  3. We all hope battery technology will improve enough to make electric cars attractive, but if it doesn’t I for one would pay a very hefty price, perhaps £5/litre for fuel, before I abandoned my car. Fortunately it is certainly technically possible to capture carbon dioxide from the atmosphere or from vehicles for much less than that.

    The options I favour revolve around quicklime (CaO). The average factory gate quicklime cost in the USA is published and was $84/te in 2007. The material is made by decomposing limestone (CaCO3) in a kiln. When quicklime recombines with carbon dioxide it may form either the carbonate (CaCO3) or, if in solution, the bicarbonate (Ca(HCO3)2). Based on the carbonate, the cost of quicklime per ton of carbon dioxide absorbed would be $107.

    There are of course other essential costs including the cost of capturing the carbon dioxide produced as the quicklime is made.

    One option is simply to dump the quicklime in the ocean refer

    Another is to use quicklime to turn sodium or potassium carbonate into the hydroxide by precipitating the insoluble calcium carbonate as in the Kraft paper process. Solutions of sodium or potassium hydroxide can be used to capture carbon dioxide from the air by reforming the carbonate.

    Alternatively the hydroxide could be used in a vehicle either in solution or perhaps, as weight is crucial, as the solid or a slurry. At the limit of solubility the range would be 100 miles for 150 kg of potassium carbonate solution in a vehicle doing 30 miles per imperial gallon. This compares favourably with current battery technology and recharging with potassium hydroxide solution at the gas station would be much quicker than recharging a battery. Moreover the vehicle could still be driven for hundreds of miles with the hydroxide exhausted, if necessary.

    If quicklime could be used directly as a solid, 150 kg would give a range of 228 miles. But reaction rate might be too low, carbonate might blanket the quicklime giving poor conversion and the solid might stick together with all the water vapour in the exhaust gases (just like cement which of course has quicklime as the key component) making discharge very difficult.

    I have not yet worked out whether the higher concentration of carbon dioxide in exhaust gas is enough to tip the cost advantage against capture from the atmosphere. The logistics of the latter certainly look much easier and of course there are economies of scale and a free choice of location to suit sequestration and perhaps provide low cost energy/fuel.


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