A way to curb global warming: Suck carbon emissions right out of the air?

Most efforts to address carbon emissions focus on preventing them from entering the atmosphere in the first place. But how to get rid of CO2 already there? Start-ups are developing prototype air-capture systems.

Ayesha Rascoe/Reuters/File
The American Electric Power Co.'s cooling tower at its coal-burning plant is shown in 2009 in New Haven, W.Va. Researchers are looking for ways to remove carbon dioxide already in the atmosphere as a possible way to combat global warming.

Efforts to combat global warming, triggered and reinforced by rising levels of carbon dioxide as humans burn fossil fuels and convert forests to farmland, largely focus on preventing CO2 from entering the atmosphere in the first place.

But small groups of researchers are pursuing a complementary approach. They are looking for ways to remove CO2 already in the air.

On small scales, the approach has been used since the 1930s at dry-ice facilities, as well as to scrub CO2 from the air on submarines and on the International Space Station. Proposals to use air capture to help reduce atmospheric CO2 concentrations first appeared in 1999.

However, "over the last two or three years, there's been a lot of new [research] publication in this field," says Alain Goeppert, a researcher with the Loker Hydrocarbon Research Institute at the University of Southern California (USC).

The interest is driven in no small part by a handful of start-up firms that are developing prototype air-capture systems. But it's also driven by the recognition that CO2 concentrations in the atmosphere already exceed a level that some scientists say stands the best chance of holding global warming by the end of this century to about 2 degrees Celsius (3.6 degrees Fahrenheit) above preindustrial levels.

Air capture essentially involves passing ambient air across liquid or solid materials that absorb CO2. Conceptually, it's similar to extracting CO2 from coal-fired power-plant emissions.

But air-capture advocates note that some 30 percent of the world's CO2 emissions come from cars, aircraft, and other mobile "nonpoint" sources, where scrubbers at the tailpipe are impractical.

Tackling emissions from these sources will be necessary in order to meet any goal for stabilizing CO2 levels in the atmosphere, because the CO2 that oceans or terrestrial vegetation don't take up remains in the air for centuries. Stabilizing concentrations essentially means stopping the emission of additional CO2.

"Without air capture, nonpoint sources of emission will need to be phased out over the next few decades if we want to stabilize the climate," argues Klaus Lackner, director of Columbia University's Lenfest Center for Sustainable Energy and a founder and director of Kilimanjaro Energy, one of the start-ups working on air-capture technologies, in an article published last year in the Proceedings of the National Academy of Sciences.

Air capture has its critics, who argue that the approach is likely to be too expensive to implement in a way that would have a significant impact on emissions.

For instance, a team led by Kurt House and Howard Herzog at the Massachusetts Institute of Technology has estimated that the full cost to remove a ton of carbon from the air would be around $1,000 for an air-capture system, compared with as much as $100 per ton for a system that scrubs the CO2 at the smokestack. The team nevertheless noted that beyond the year 2050, the approach "may even be deployed to reduce atmospheric concentrations of CO2 below current concentrations."

In the end, however, says USC's Dr. Goeppert, virtually all of the cost estimates "are quite speculative.... To really know how much it's going to cost, you're going to need to build some demonstration plants."

You've read  of  free articles. Subscribe to continue.
Real news can be honest, hopeful, credible, constructive.
What is the Monitor difference? Tackling the tough headlines – with humanity. Listening to sources – with respect. Seeing the story that others are missing by reporting what so often gets overlooked: the values that connect us. That’s Monitor reporting – news that changes how you see the world.

Dear Reader,

About a year ago, I happened upon this statement about the Monitor in the Harvard Business Review – under the charming heading of “do things that don’t interest you”:

“Many things that end up” being meaningful, writes social scientist Joseph Grenny, “have come from conference workshops, articles, or online videos that began as a chore and ended with an insight. My work in Kenya, for example, was heavily influenced by a Christian Science Monitor article I had forced myself to read 10 years earlier. Sometimes, we call things ‘boring’ simply because they lie outside the box we are currently in.”

If you were to come up with a punchline to a joke about the Monitor, that would probably be it. We’re seen as being global, fair, insightful, and perhaps a bit too earnest. We’re the bran muffin of journalism.

But you know what? We change lives. And I’m going to argue that we change lives precisely because we force open that too-small box that most human beings think they live in.

The Monitor is a peculiar little publication that’s hard for the world to figure out. We’re run by a church, but we’re not only for church members and we’re not about converting people. We’re known as being fair even as the world becomes as polarized as at any time since the newspaper’s founding in 1908.

We have a mission beyond circulation, we want to bridge divides. We’re about kicking down the door of thought everywhere and saying, “You are bigger and more capable than you realize. And we can prove it.”

If you’re looking for bran muffin journalism, you can subscribe to the Monitor for $15. You’ll get the Monitor Weekly magazine, the Monitor Daily email, and unlimited access to CSMonitor.com.

QR Code to A way to curb global warming: Suck carbon emissions right out of the air?
Read this article in
QR Code to Subscription page
Start your subscription today