Cross-posted from ecomagination.

What if, in addition to curbing greenhouse gas emissions, we could capture them from the air? That’s the question that prompted Marc Gunther, an author and contributing editor at Fortune magazine, to write the e-book Suck It Up, a Kindle Single. Below is an excerpt from the book on the history of the start-up Kilimanjaro Energy, a private company that is seeking to solve the carbon extraction equation.

Working at the Los Alamos National Laboratory during the 1990s, Klaus Lackner had numerous interests: the behavior of high explosives, nuclear fusion, and self-replicating machine systems. At some point, he turned his attention to the technology used to capture CO2 from the smokestacks of coal plants — technology in which the U.S. government has invested billions of dollars, with little to show for it. He began to wonder whether it might make more sense to scrub CO2 from the atmosphere. So when his daughter Claire asked for help with a science project, he asked her: “Why don’t you pull CO2 out of the air?”

Chemical engineers have known for decades that sodium hydroxide, a caustic base also known as lye, will bind with CO2, an acid, to make carbonates. That’s basically how CO2 is removed from the air so people can continue to breathe on submarines or in spaceships. Claire accomplished the feat by filling a test tube with a solution of sodium hydroxide, buying a fish-tank pump from a pet store, and running air through the test tube all night. By the next day, some of the sodium hydroxide had absorbed CO2, creating a solution of sodium carbonate.

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“I was surprised that she pulled this off as well as she did,” Lackner recalls, “which made me feel that it could be easier than I thought.”

Duly inspired, Lackner set off on a quest to design a machine to pull CO2 out of the air. This would seem to be much harder than collecting carbon dioxide from the smokestacks of power plants that burn coal or natural gas, where concentrations of CO2 are about 12 percent (for coal) or 4 percent (for natural gas). Less than 0.04 percent of the air is CO2. Still, in a presentation called “Carbon Dioxide Extraction From Air: Is It An Option?” that he wrote in 1999 with Hans-Joachim Ziock, a colleague at Los Alamos, and the late Patrick Grimes, an expert in chemical processes, Lackner identified an important role for air-capture technology:

While it may be cost-advantageous to collect the carbon dioxide at concentrated sources without ever letting it enter the atmosphere, this approach is not available for the many diffuse sources of carbon dioxide. Similarly, for many older plants a retrofit to collect the carbon dioxide is either impossible or prohibitively expensive. For these cases we investigate the possibility of collecting the carbon dioxide directly from the atmosphere. We conclude that there are no fundamental obstacles to this approach and that it deserves further investigation.

This remains key to the appeal of air capture: Because greenhouse gases are dispersed around the globe, they can be extracted from the air anywhere. Carbon dioxide spewing from a tailpipe in Sao Paulo or a coal plant in China can be captured by a machine in Iceland or the Middle East, because the atmosphere functions as a conveyor belt, moving CO2 from its sources to any sink. That’s important, because while we can envision a world where most or all of the electricity we use comes from nuclear, solar, or wind energy, or from fossil fuels where the CO2 is captured at the power plant, it’s harder to see how emissions from cars, trucks, trains, ships, and planes can be eliminated. The beauty of air capture, Lackner and his colleagues explained, is that “one could collect CO2 after the fact and from any source … One would not have to wait for the phasing out of existing infrastructure before addressing the greenhouse gas problem.” Air capture plants, they wrote, could be located atop the best underground reservoirs for storing CO2, which may be in isolated locations. This fact is key to the business plans of all the air-capture start-ups. In only one regard was Lackner’s paper clearly mistaken — he estimated that the cost of air capture would be “on the order of $10 to $15 per ton,” a target that now looks wildly optimistic.

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In 2001, Lackner joined the faculty at Columbia, as chair of the department of earth and environmental engineering. There, he met three men who would help him launch air capture into the business world: Wallace “Wally” Broecker, a Columbia professor and climate scientist who is thought to have coined the term “global warming” back in 1975; Allen Wright, a self-taught engineer who oversaw research at Biosphere 2, an artificial ecological system in Oracle, Ariz., managed by Columbia; and Gary Comer, the philanthropist and founder of Lands’ End.

After Comer sailed through the Northwest Passage on his 151-foot yacht during the summer of 2001, he grew concerned about climate change. By the following spring, Comer had been diagnosed with advanced prostate cancer and felt an urgent need to do something about the problem. He decided to pour millions of dollars into climate research at Columbia, working closely with Broecker. When Broecker asked him to meet with Lackner and Allen Wright, Comer agreed. Lackner need an investor to start an air-capture company. Wright needed a job because Columbia had severed its ties with Biosphere 2, and he became the company’s first CEO. He brought aboard his older brother Burt, a former Tucson firefighter who was good at building things.

Comer agreed to invest $8 million in a start-up called Global Research Technologies (GRT), which would be run by Allen Wright and headquartered in Tucson. In 2004, GRT set up shop.

The company stumbled at first. As Lackner explained it to me, air capture is a multi-step process — a chemical absorbent first has to bind with CO2, after which the CO2 needs to be separated from the absorbent and compressed into a liquid to be sold or stored. “The hard part is getting the CO2 back off,” he said. GRT’s first absorbent was sodium hydroxide, which effectively captured CO2. But the bond between them was so strong that separating the CO2 required a great deal of energy. In 2007, after testing other absorbents, GRT had devised a new air-extraction technology that uses a plastic resin that bonds with CO2 when dry and gives it back when wet. This was hailed as a breakthrough in a company press release quoting, among others, Jeffrey Sachs, the director of the Earth Institute at Columbia. “This significant achievement holds incredible promise in the fight against climate change,” Sachs said. “Thanks to the ingenuity of GRT and Klaus Lackner, the world may, sooner rather than later, have an important tool in this fight.” It would be later rather than sooner. In 2008, Wright was replaced as CEO by William “Billy” Gridley, an investor in the firm and a former managing director at Goldman Sachs.

Two years later, GRT pivoted again. The company moved to San Francisco, renamed itself Kilimanjaro Energy, and brought on a new CEO, Nathaniel “Ned” David, a serial entrepreneur and venture investor. The company’s new name reflected its goal: To harvest CO2 from the atmosphere and use it to make transportation fuels with a much lower carbon footprint than gasoline or diesel. “We’re going to try to make fuels, while simultaneously saving the snows of Kilimanjaro,” David said.

Of course, Kilimanjaro first must solve the technology issues associated with air capture. They are not trivial. The company’s technology has yet to exit the lab: David and his staff of fewer than a dozen people are currently designing machines that will be exposed to wind currents that will push air past large flat filters until they are loaded with CO2; the filters will then be lowered into a closed, humid chamber where the trapped CO2 will be released from the filter, generating air with a 5 to 10 percent concentration of CO2. This enriched air requires further processing to create a stream of nearly pure CO2 that can be liquefied for enhanced oil recovery — a final step that is turning out to be harder than anticipated. “Most of our technical risk is in the future,” David acknowledges. “We have not solved all the problems.”