One of the most tantalizing possibilities for dealing with the accumulation of carbon dioxide in the atmosphere is to take it out using brute force methods of chemistry, biology or even geology. I discuss such "air capture" of carbon dioxide in Chapter 5 of The Climate Fix. As the climate debate continues to generate more heat than light, technologies of air capture are continuing to improve.
On Saturday, the New York Times had a smart article with an update on the technology:
[A] Canadian company has developed a cleansing technology that may one day capture and remove some of this heat-trapping gas directly from the sky. And it is even possible that the gas could then be sold for industrial use.A crucial question of course is cost. In a 2009 paper on air capture (here in PDF), I compared the idealized costs of using air capture as the main mechanism to achieve stabilization of carbon dioxide concentrations, based on existing cost estimates of the technology, with the costs of stabilization under conventional mitigation policies, as estimated by the IPCC and Stern Review.
Carbon Engineering, formed in 2009 with $3.5 million from Bill Gates and others, created prototypes for parts of its cleanup system in 2011 and 2012 at its plant in Calgary, Alberta. The company, which recently closed a $3 million second round of financing, plans to build a complete pilot plant by the end of 2014 for capturing carbon dioxide from the atmosphere, said David Keith, its president and a Harvard professor who has long been interested in climate issues.
The carbon-capturing tools that Carbon Engineering and other companies are designing have made great strides in the last two years, said Timothy A. Fox, head of energy and environment at the Institution of Mechanical Engineers in London.
“The technology has moved from a position where people talked about the potential and possibilities to a point where people like David Keith are testing prototype components and producing quite detailed designs and engineering plans,” Dr. Fox said. “Carbon Engineering is the leading contender in this field at this moment for putting an industrial-scale machine together and getting it working.”
In that analysis I found that under the identical assumptions used by IPCC/Stern, air capture which cost between $100 and $500 per tonne of carbon would lead to overall economic costs of 0.5% to 3.0% of overall GDP to achieve stabilization at 450 ppm. This was a surprising result, because for conventional mitigation Stern estimated the costs at up to 4% of GDP and IPCC up to 5.5%. Critics of my paper complained that air capture was not yet possible. My reply was that neither was conventional mitigation possible, so why not pursue both?
A more recent literature review of air capture technology and economics by Goeppert et al (2012, here, $) found estimated costs of $50 to $3,700 per tonne of carbon. They conclude:
Direct CO2 capture from the air is still in its infancy. The cost of a commercial plant will depend on many factors including the process used as well as the cost of labor, materials and energy. While there is no question that the capture of CO2 from the air is possible, more research and development is clearly needed to optimize this technology and determine its economic viability. Only with the construction of demonstration and pilot plants will we have a clearer understanding of the total cost associated with DAC. A few start-up companies including Carbon Engineering, Kilimanjaro Energy, Global Thermostat and Climeworks have started such an effort. Some of the proposed devices and prototypes for the capture of CO2 from the air are shown in Fig. 14. It should also be pointed out that the costs associated with DAC units are not ‘‘stand alone’’. Once captured, the CO2 will be used for applications such as enhanced oil recovery (EOR) or recycling into chemicals and fuels including methanol, DME and hydrocarbons (CCR). This will give an economic value to the captured CO2, lowering the de facto cost of DAC and provide a more favorable overall picture of the process. Water (moisture) could also be separated from the air at the same time as CO2, which could provide clean water as an added value. . .Ultimately, the test of air capture will not come from journal articles or policy debates, but actual engineering in the real world. Of the actual costs, Goeppert tells the NYT, "We won’t know for sure until someone builds a pilot plant."
CO2 from the atmosphere provides a nearly inexhaustible carbon source for humankind. Combining carbon capture and storage with subsequent withdrawal for technological recycling based on an anthropogenic chemical carbon cycle offers a feasible new solution to our carbon conundrum. As fossil fuels are becoming scarcer and increasingly depleted, carbon capture and recycling offers a renewable and safe source for carbon containing fuels and their products. It also liberates humankind from the limitations associated with the biological natural carbon sources including crops and biomass. The chemical carbon cycle constitutes humankind’s practical technological analog of nature’s photosynthetic CO2 recycling. At the same time, the anthropogenic chemical carbon cycle (CCR) also helps to mitigate the environmental harmful effect of excessive CO2 in the atmosphere. Instead of just a greenhouse gas harmful to the Planet’s ecosystem, CO2 should therefore be considered as a valuable industrial C1-feedstock.
The good news is that far from the glare of the climate debate, scientists and engineers are hard at work on advancing air capture technology. And guess what? They are making progress. Watch this space.
A. Goeppert et al. 2012. Air as the renewable carbon source of the future: an overview of CO2 capture from the atmosphere, Energy & Environmental Science, 5:7833-7853 DOI: 10.1039/C2EE21586A
R. A. Pielke, Jr. 2009. An idealized assessment of the economics of air capture of carbon dioxide in mitigation policy. Environmental Science & Policy 3:216-225