by Kahrin Deines
Dec 04, 2008

In an unassuming building on the outskirts of Tucson, a close-knit team of innovators have developed a prototype machine that might one day be hailed as the thing-a-ma-jig that helped beat back global warming.

It’s hard to miss the irony that the device, likened to an artificial tree, was born in the hot, dry desert landscape of Arizona.

Here, where little but cactus absorb CO2 from the sweltering air, a scientist and an entrepreneur came together to develop a machine that mimics aspects of photosynthesis.

“Just like a tree, it has leaf-like surfaces over which the air flows and then the CO2 is taken out of the air by getting in contact with these surfaces,” said Klaus Lackner of Columbia University in New York. The tall, debonair physicist is largely credited with inventing the new technology.

Lackner’s vision and the worry that rising carbon-dioxide levels could trigger an abrupt change in climate prompted the late Gary Comer, founder of the Lands’ End clothing company, to invest in his idea. With Comer’s seed money and advice from Columbia’s climate sciences pioneer Wallace Broecker, a company called Global Research Technologies opened shop in 2004 to turn Lackner’s dream of a synthetic tree into a reality.

All told, Comer’s foundation invested $6 million in the development of the technology, part of some $50 million that he dedicated to research that addresses climate change.

The synthetic tree can’t yet turn sunshine into fuel as plants do but it can beat plants at half their own game, according to Lackner, chairman of Global Research Technologies. “We can pack the leaves much more tightly because they don’t have to get sunshine,” he said. “And, consequently, we can absorb about 1,000 times as much CO2 as an equally sized tree could absorb.”

By sucking carbon dioxide out of the air at a rate that could potentially offset CO2 emissions from humans, the machine – officially called a “CO2 scrubber” – might change the carbon playing field. Critics, though, question whether it will ever be economically feasible to deploy a whole fleet of such scrubbers throughout the world, let alone dispose of the CO2 they gather below ground.

At first sight, Lackner’s machine doesn’t look much like a planetary scrubber or a tree.

It’s a big box with sheets of special plastic hanging in it. The sheets are able to draw the CO2 out of the air by ionizing the gas so it binds to the plastic like a magnet. Once the CO2 is collected, it’s removed by a blast of humidity, allowing the plastic resins to be reused. Without the removal process, the CO2 couldn’t be sequestered and the machine would be an energy guzzler.

A full-size version of the device, which Lackner envisions at about the same size as a 40-foot-long shipping container, could remove as much as one ton of carbon dioxide from the air in a day’s operation.

One ton, of course, wouldn’t make much of a dent in the approximate 30 billion tons of CO2 emissions that enter the atmosphere every year. But if enough of these scrubbers were built – and enough would number in the tens of millions by Lackner’s estimate – they might be able to tilt the carbon balance away from the brink of severe climate change.

A fleet – or forest – of the scrubbers could be deployed, placed in locations where there is either a demand for CO2, such as near greenhouses that use it to boost plant growth, or near places where it can be stored.

Tens of millions is a big number, though, and right now Global Research Technologies estimates it will cost them $250,000 to build just one scrubber unit. Lackner and Allen Wright, president of GRT, are currently looking for private investors willing to ante up the costs of building and deploying the first real scrubber unit, which they said could be finished in two years’ time.

Tens of millions of scrubbers, of course, would take more time and more money.

Lackner said the large figures just reflect the size of the problem. “The number of cars, the number of trucks – all of those are numbers on that scale, so it’s not impossible to get there,” he said. “Because we are dealing with a problem of a billion cars, we are also having to put up a solution that is on that same scale.”

Global Research Technologies completed a scaled-down prototype of the CO2 scrubber last year. And it’s working, according to Lackner, who said it can keep up with the emissions from one car.

Yet direct air-capture technologies for CO2 have been viewed skeptically in the past. The reason has to do with carbon dioxide concentrations in the air. Even with rising levels, the gas sits at a relatively dilute concentration of about only 380 parts per million. But it can make up 10 percent or more of the smog belched directly from a power plant’s smokestack

As a result, the U.S. Climate Change Technology Program, which coordinates research into technologies capable of reducing greenhouse gas emissions, has focused on capture techniques designed for use at power plants. Energy-independence advocates as well have hailed carbon capture from power plants as a path to so-called clean coal.

Direct air-capture technologies, such as Lackner’s, on the other hand, have been sidestepped for now, with the Climate Change Technology Program defining them as a strategy for the long-term – 40 to 60 years from now.

“Clearly one of the challenges is just the enormous volume of air you have to handle [with direct air capture],” said Robert Socolow, the Princeton scientist who developed the “stabilization wedge,” a popular conceptual tool for thinking about how to halt climate change using existing technology. There’s eight-tenths of a gram of CO2, weighing about as much as a paper clip, in a cubic meter of air, he said.

Yet a gallon of gasoline generates approximately 20 pounds in CO2 emissions. So even though CO2 is still laced thinly throughout the atmosphere, its levels are far higher than in past climate warming cycles that have occurred over the last 650,000 years. Barring serious efforts to reduce emissions from the burning of fossil fuels, the concentration of CO2 is expected to surge higher still, accelerating the warming that already poses risks of coastal flooding and inland drought.

As a result, Socolow and others are starting to take direct air-capture technologies seriously and the American Physical Society, a society of physicists with more than 46,000 members, has just approved a $25,000 grant for him to organize a study on the various options being researched. The society’s grants are often supplemented by money from outside foundations.

The new study will look at capture techniques that could be used to suck CO2 from the air anywhere, which is how Lackner’s invention operates, as well as those tailored for use at a power plant. According to Socolow, it will be the first independent assessment of such technologies and will begin sometime this fall.

Lackner and the group at Global Research Technologies, located in a 10,000-square-foot building near Tucson’s airport, aren’t the only scientists exploring how to capture carbon dioxide directly from the air. In fact, a colleague of Lackner’s at Columbia, Peter Eisenberger, is testing CO2 absorbers that could inhale and exhale carbon dioxide in response to temperature swings.

And in Canada, David Keith, at the University of Calgary, has been working with technology similar to Lackner’s first prototype, with the goal of building a mega-CO2 scrubbing facility. Keith tested a version of his CO2 scrubbing tower last summer, as featured in the Discovery Channel’s new “Project Earth” television series.

Still other work is underway by Julio Friedmann at Lawrence Livermore National Laboratory, based in Livermore, Calif., where scientists are looking for a catalyst that could speed how quickly the CO2 binds to an absorber. “It’s a very interesting idea, it’s a new idea, and it’s a hard idea,” Socolow said of general capture concepts. “So, we will try to sort out whether this is something for the next decade or for the longer-term.”

All of the air-capture technologies, however, require a place to put the carbon dioxide once it’s collected. And, at the moment, no CO2 sequestration areas currently operate in the United States.

Although the U.S. Department of Energy is presently researching the viability of underground carbon sequestration, the effort is still in a preliminary phase.In fact, a September report by the U.S. Government Accountability Office concluded that slow-paced progress by the Energy Department and other agencies has “left critical gaps that impede our understanding” of the potential use of carbon capture and storage technologies.

At the international level, the Group of Eight industrialized countries committed at a July meeting to building 20 large-scale carbon capture and storage sites by 2010. But, in a report released in October, the Paris-based International Energy Agency stated that current investment levels are nowhere near what’s required to achieve the G8 goals.

Nevertheless, most research continues with an eye toward capturing the CO2 at a high-emissions source, such as a coal-burning plant.

“At a power plant, you have a large amount of CO2 so you can put it into a big pipe and move it” into storage, said Daniel Schrag, director of Harvard University’s Center for the Environment. “But if you have lots of small units all over the place [as Lackner proposes], think of the plumbing that will require.”

Proponents of direct air-capture point out, however, that vast emissions come from mobile sources, such as cars or planes.

“How do you de-carbonize a jumbo jet?” Friedman asked. “How do you de-carbonize a barge going across the ocean?” There are parts of the economy where it’s going to be hard to wring out the carbon, he said.

A CO2 scrubber, such as Lackner has developed, could deal with those emissions because it does not have to be connected to a specific emissions source to clean the atmosphere.

“The concept of air capture of carbon dioxide is applying a local solution to a global problem in a sense that the device can, and does, capture CO2 emissions at one location that could have been emitted virtually anywhere on the surface of the planet,” said Wright.

And, while the future may bring electric or hydrogen-powered cars, gasoline may still be the cheapest way to fuel planes or barges for decades to come.

In any case, Lackner insists the location or size of a CO2 scrubber doesn’t matter. “I move the prophet to the mountain, not the mountain to the prophet,” he said. “I put the unit near a place where I can sequester [carbon dioxide].”

Moreover, he said, they could initially pair the machine with a CO2 consumer – and this is why Lackner and the Global Research Technologies team think they can bring the scrubber to market even without a place to sequester the carbon dioxide at first.

Dry-ice users, soda-pop makers or oil-shale miners could all be prospective customers, according to Lackner. And Global Research Technologies could edge into these CO2 markets, he said, by offering lower prices since the scrubber could be located near CO2 consumers to bypass the energy costs of transport.

If the first scrubbers can turn a profit in these existing CO2 markets, Lackner and Global Research Technologies could build up economies of scale and fine tune the scrubber design in preparation for a larger launch that could really make a dent in carbon dioxide levels. 

The question remains, however, whether their price for CO2 – at first an estimated $100 a ton – could really be competitive with current purchase prices.

“These are all technologists,” Schrag said. “So when they talk about prices you have to be very careful.” Charging $100 per ton of CO2, he said, would be like charging $300 or $400 per ton of coal, when it currently trades at $30 or $40.

If the U.S. and other countries make emissions reductions mandatory through cap and trade regimes, however, CO2 trading prices could rise as companies are forced to buy up offsets to balance out their emissions. In such a setting, Global Research Technologies – and other companies that capture carbon dioxide – could sell offsets.

In any case, although the future trading price of CO2 remains unknown, the allure of what Lackner and other air-capture technology proponents say they can offer is irrefutable.

“I could collect 100 tons of CO2 and come to you and say: ‘Would you like a car that has no CO2 emissions over its lifetime?’” Lackner said. “Because the CO2 emissions of this car over its lifetime will be roughly 100 tons and I could have collected all of the CO2 the day the car was made.”