RESEARCHERS DEFEND DIRECT AIR CAPTURE AS KEY TO FUTURE CO2 MITIGATION STRATEGY

Tamar Hallerman
GHG Monitor
08/03/12

Despite critiques surrounding the high cost of the novel technology, it is critical to maintain support for direct air capture as researchers continue to search for and fine tune equipment that could be an invaluable part of the world’s climate change mitigation strategy, Columbia University researchers said in a commentary published this week. In the most recent issue of the journal Proceedings of the National Academy of Sciences, researchers at Columbia University’s Earth Institute argue that while the cost of direct air capture (DAC) technology is unknown but will undoubtedly be expensive for its initial incarnations, political and financial support is necessary in order to further develop the technology to a level where it is possible to gauge its potential for climate change mitigation. “The inability to produce accurate cost estimates for a nascent technology should not be considered a reason for withholding support,” the commentary says. “Indeed, air capture is clearly feasible, and there are several lines of argument that suggest that its cost could well come down to a level that would make air capture economically interesting. Air capture would provide a different approach to reducing CO2 concentrations in the atmosphere.”

Controversial Technology

While still in its infancy, DAC has been seen as a particularly promising method for capturing CO2 emissions from the transport sector—which accounts for nearly half of all CO2 emissions—and small point sources, where it is too expensive to directly capture from the source itself. Most technologies under development utilize the absorption or adsorption of a sorbent on collector surfaces. Proponents say that in addition to the benefit of capturing emissions that have already been emitted into the atmosphere, leading to net negative emissions, DAC technology could be beneficial because it allows for the continued use of fossil fuels in carbon-limited scenarios. 

The field, however, is still in its infancy and aside from a few experimental results from lab tests being published, little information on the technology exists in the public realm. The technology is often compared with climate geoengineering technologies and is considered fairly controversial because of that fact. Critics often argue that cheaper alternatives for climate change mitigation exist and that DAC would provide incentive for governments to delay any action on climate change altogether. Other criticisms focus on the technology’s high projected cost estimates. A study published last summer by the American Physical Society concludes that while DAC may be technically feasible, the cost of the technology, which it estimates to be at least $600 per ton of CO2, is prohibitively high and that it will likely play little to no role in carbon mitigation efforts over the next couple of decades. Other reports from the Government Accountability Office and Massachusetts Institute of Technology and Stanford researchers published within the last year have also largely dismissed DAC on cost and readiness grounds.

Developers Defend Technology

However, in the commentary, developers of the technology at Columbia defend the technology and its future as a potential emissions mitigation technology. In an interview with GHG Monitor, head author Klaus Lackner, a professor of geophysics at Columbia University’s Earth Institute, said DAC technology is technically feasible and has the potential to be cost competitive. He said that submarines and spaceships have been utilizing similar technologies for decades to maintain safe levels of CO2 within their vessels. Lackner agreed that current cost estimates for DAC are high, but that people still should not give up on the technology, particularly given that technologies like solar, wind and electric vehicles followed similar development trajectories before they were commercialized. “In a nutshell, the argument I have about the [American Physical Society] study is that there’s nothing wrong with the air cost estimate, it’s right,” Lackner said. “But to say that because there is an existing technology which could do air capture at $600 a ton and that is too expensive, therefore we cannot do air capture is wrong, because if you look at wind or solar energy they were 50 times more expensive in the past than they are today.” He said that like those industries, the price will go down once the technology is further developed and that it would be premature to make a judgment now. In addition to the cost of alternatives like solar and wind energy, the price governments may put on carbon could also play a large role in the future viability of DAC, according to the report. “If climate change were universally perceived as a serious calamity, air capture as an emergency measure might be valuable at costs much higher than $100/ton CO2,” the report says.

Lackner also disputed the argument that DAC will enable governments to further punt action on climate change. “I would argue that really doesn’t apply. I would turn it around and say that if that’s the criticism, then do you really want to fight this problem with one hand tied behind your back?” he said in the interview. “Because you will have to deal with all of these emissions and you may have the need to deal with CO2 which has already escaped into the atmosphere. So you need tools to do that and I think it’s a bad logic to say that for those reasons you don’t need to start now. We’re already in a hurry.” Lackner said that if governments care about making truly deep cuts in emissions, they should invest in DAC. “We will need to reach a point where for every ton of CO2 emitted or coming out of the ground, another ton must be put back. And you cannot ignore half of the problem [the transport sector] if you want to solve this,” Lackner said. “The timeline is not such where you can just focus on coal-fired power plants first and then move on to air capture sometime in the distant future.”

DAC Also Boasts Powerful Supporters in Washington

While DAC has its critics, it also does have some powerful backers in Washington. In 2009, Energy Secretary Steven Chu and John Holdren, President Obama’s science adviser, both mentioned the technology as a potential mitigation method. Congress has also been attracted to the technology in recent years. In spring 2011, the Senate Energy and Natural Resources Committee passed a bill that would offer $10 million worth of prizes to the first researchers to successfully develop bench- and demonstration-scale DAC technologies. However, that bill has collected dust while waiting for action on the Senate floor and is not expected to be considered before the end of this Congress.