What is your new paper?

Pielke, Jr., R.A., An idealized assessment of the economics of air capture of carbon dioxide in mitigation policy. Environ. Sci. Policy (2009), doi:10.1016/j.envsci.2009.01.002

How can I get a copy?

The final version will be placed online here. Until that is available you can find the corrected proofs here in PDF.

What is the paper about?

Here is the abstract:

This paper discusses the technology of direct capture of carbon dioxide from the atmosphere called air capture. It develops a simple arithmetic description of the magnitude of the challenge of stabilizing atmospheric concentrations of carbon dioxide as a cumulative allocation over the 21st century. This approach, consistent with and based on the work of the Intergovernmental Panel on Climate Change (IPCC), sets the stage for an analysis of the average costs of air capture over the 21st century under the assumption that technologies available today are used to fully offset net human emissions of carbon dioxide. The simple assessment finds that even at a relatively high cost per ton of carbon, the costs of air capture are directly comparable to the costs of stabilization using other means as presented by recent reports of the IPCC and the Stern Review Report.

Is air capture technically possible?

Yes, it is possible.

Is air capture a magic bullet? Why don’t we just capture carbon dioxide directly from the air and be done with it?

Air capture is not a magic bullet to stopping the carbon dioxide build-up in the atmosphere. There are several obstacles to deployment of air capture at a scale significant enough to play a role in mitigation policy.

The first obstacle is the immaturity of the technology. Some scientists and engineers are working on it, but it really has not received significant attention or resources. There are various proposals for air capture technologies and some of these proposals have been prototyped.

The second obstacle is sequestration. What do you do with the carbon dioxide when it is captured? This is the same obstacle to the carbon capture and storage from coal power plants. Because the IPCC, IEA, G8, US, EU and others are all banking in a big way on such storage being possible, we’ll know soon, perhaps within a decade how viable an option sequestration is –for both CCS and air capture. There is also the possibility that people will react negatively to sequestration, like some do to nuclear waste. So there could be social objections.

The third obstacle is how air capture changes the debate. If air capture is a possible contribution to mitigation some believe that it will lessen the ability to use climate policies to get at other agendas. So for some there is a reflexive almost irrational opposition to air capture simply because it is a technological fix. For example, commenting on air capture a representative of an environmental NGO explained that it took away the ability to use climate change to get at other issues:

Such techno-fixes also miss the point of the environmental degradation brought on by the use of fossil fuels, he said.

Carbon scrubbers won’t stop oil spills, habitat-destroying strip mining and ozone, he said. “It’s like having cancer and putting a Band-Aid on it,” he added.

Or as Ted Parsons, a professor at the University of Michigan, commented on air capture (PDF):

Can we continue to rely on specific technical correctives for each problem as it arises – whether these are changes in production processes to further reduce environmental burdens per unit of output, or direct environmental interventions to offset those burdens like air capture? Alternatively, can we continue to rely on narrowly drawn policies to motivate reductions in whatever specific forms of production and consumption pose the clearest immediate risks? Or must we somehow find a way to address the larger-scale question of limiting the aggregate scale of human population and economic activity, and seek to identify some means to achieve this that is compatible with humane, democratic states that value individual liberty?

Such concerns about technical fixes are commonplace.

A fourth obstacle is cost, which is what my paper focused on.

What did you learn about the costs of air capture?

The analysis in my paper concludes:

To summarize, the idealized exercise conducted here finds that air capture using 2008 technology is of about the same costs as the costs estimates for stabilization at 450 ppm or 550 ppm carbon dioxide presented by IPCC (2007a) and Stern (2007). If the costs of air capture decrease to $100 per ton of carbon, then over the 21st century air capture would in fact cost much less than the costs estimates for stabilization presented by IPCC (2007d) and Stern (2007). This surprising result suggests, at a minimum, that air capture should receive the same detailed analysis as other approaches to mitigation.

This should not be too surprising a result for people familiar with the marginal cost curves of abatement of carbon dioxide which are similar to (or large than) the costs of air capture presented in my paper. I took efforts in my paper to ensure that my simple analysis erred on the side of overestimating the costs of air capture. Another way of looking at the costs of air capture is with respect to the damages associated with doing nothing. Air capture easily costs less than these damage costs as presented by IPCC and the Stern Review. So whatever other objections one might have to air capture, costs do not seem to be among them.

In short, if air capture costs too much as an approach, then so too do other forms of mitigation, because they costs about the same. If other forms of mitigation are judged to be worth the expense, then air capture deserves more attention than it has received in the past, because its costs are in the same ball park .

Who else thinks air capture is important?

Lots of people. Jim Hansen is a notable example. In my paper I quote him as follows:

‘‘a feasible strategy for planetary rescue almost surely requires a means of extracting [greenhouse gases] from the air”

Realistically, what role do you think air capture will play in mitigation?

Well, it seems fairly obvious that mitigation policies are going to face serious difficulties in slowing down, much less reversing, the growth in carbon dioxide emissions. But let’s take an optimistic view that the world sets forth immediately on a path of decarbonization and sustains that effort over the next few decades. Even under such an optimistic scenario, the world may wish at that time to further reduce concentrations in the atmosphere, as mitigation efforts may not be 100% successful. Air capture will be the only way to do that, and so could be a form of “mopping up” whatever is left of the task of mitigation.

Of course, there is a pessimistic scenario as well, which has the world not doing much to reduce emissions and seeing concentrations grow rapidly. Under such a scenario, the world may wish to remove carbon dioxide directly from the air. Air capture would of course be necessary under such a scenario as well, and at a much larger scale.

In either case, there can be little reason not to pursue the technology of air capture even though it may or may not have a significant role to play in future mitigation policies. In the end ask yourself this question:

Would it be easier to transform the global energy system and change the energy consuming habits of 6.5 (going to 10) billion people around the world in a period of a few decades, or to engineer a solution to removing carbon dioxide directly from the ambient air? I don’t know what the answer is, but I lean pretty strongly toward the latter.

My paper is certainly not the last word on this subject, and I would expect that we’ll be hearing a lot more about air capture, especially if progress on other forms of mitigation continues as it has recent decades. If climate change is indeed a planetary emergency, how can we afford to ignore air capture?