arttree1

Courtesy of Klaus Lackner

One of Lackner's potential designs for a carbon-scrubber that would suck the molecule from the atmosphere.


Artificial trees: Cap your CO2 and spew it too

by Rachel E. Gross
Oct 20, 2012

arttree2

Courtesy of Klaus Lackner

A previous "branch" design was based on a thicker plastic that was less efficient for carbon capture.

CO2 Vial

Rachel Gross/MEDILL

Lackner presented his first vial of sequestered carbon dioxide to Gary Comer in 2006, months before the philanthropist's death. It sits in the library of the Comer family's estate.

For those of us torn between concern for a warming globe and a lifestyle that relies on spewing tons of the greenhouse gases responsible for warming it, Klaus Lackner has a solution.

Suck it up.

That isn’t just tough love. The Columbia University geophysicist has spent nearly two decades developing a portable carbon scrubber to suck some of the carbon dioxide we emit back out of the atmosphere.

His contraption is inspired by the mechanics of the tree: plastic “leaves” filter the diffuse greenhouse gas and store it to prevent some of the nastier effects our fossil fuel addiction is having on the planet. If we can extract enough carbon dioxide, Lackner says, we’ll be able to offset our oil-driven lifestyles without setting the earth’s dial to self-destruct.

Biofuels and electric cars are promising, and the hydrogen fuel economy is always just around the corner. But, as the Greenland ice sheet melts, droughts and heat waves become more common, and carbon dioxide levels creep toward the earth’s tipping point, creative solutions to global warming grow more urgent. Lackner estimates that one-third to one-half of world carbon emissions come from billions of small sources—motorcycles, planes, cars. Those are the kinds of sources his scrubber would target.

Now, technological advances and a government grant are bringing his prototype scrubber closer to commercial reality, he told a gathering of top scientists at an annual climate conference held in Wisconsin recently. The Comer Conference on abrupt climate change is organized by the family of the late Gary Comer, founder of clothing company Lands’ End.

A single scrubber, which currently measures ten by five feet with a carousel-like cylinder on top, would remove one ton of CO2 per day—equivalent to the emissions produced by burning about 100 gallons of gasoline. The extracted CO2 would then be stored underground or used to make synthetic fuels. Because CO2 spreads throughout the world’s atmosphere, it can be extracted from anywhere; scrubbers might be placed en masse in deserts or in cooler regions such as Iceland, Lackner said at the conference.

Lackner's goals for carbon capture are far-ranging. He said he hopes humanity will one day be able to set its own atmospheric carbon levels, effectively controlling the earth’s thermostat. But the scrubber has limits. It doesn’t target other greenhouse gases, such as methane. And it won’t fix the increasing acidification of the oceans, which is killing coral reefs and fish populations.

“It’s part of a solution,” Lackner says. “Like anything else, it’s an option.”

Lackner is on the defensive after facing challenges to his invention. In 2011, the American Physical Society deemed large-scale carbon scrubbing a “formidable” task that could not be deployed fast enough to deal with rapid climate change. The organization wrote that the prospect of chemical carbon capture was no excuse to delay lowering the world’s carbon footprint by alternative means, and that pursuing those means—"including low-carbon electric power production and transportation"—are higher priority.

Lackner disagrees. With carbon levels already dangerously high, he says, we need all the options we can get.

“I’m not advocating procrastination,” says the physicist, who published a paper defending carbon scrubbing this July in response to APS’s position. “Far from it. I’m telling you, we already overshot. And we need a solution that allows us to come back.”

While acknowledging a high level of uncertainty, the APS estimated the cost of direct air capture at $600 to extract a ton of CO2. Lackner believes he could get it down to $30. But to achieve that kind of efficiency, first he needs “to get into the doing business,” he says. “It gets cheaper as you do.”

Before tackling the world’s carbon problems, he’s banking on some “not horribly green options” to help his scrubbing business get off the ground: he hopes to sell the gas to greenhouses in Europe, or oil companies who use it for enhanced oil recovery.

In 2004, Lackner co-founded a company for direct air capture with seed money from the late Gary Comer. He presented his first vial of sequestered carbon dioxide to Comer in 2006, months before the philanthropist's death.

The company, Kilimanjaro Energy in San Francisco, recently improved the plastic the scrubber will use to fix carbon. The material is now just a fraction of a millimeter thick—compared to a millimeter in his original model—and works six times as fast, according to Lackner. He will continue developing the technology with a six-month grant from the U.S. Office of Naval Research, which he and colleague Allen Wright secured in July.

Making direct air capture work will be necessary if we are to stabilize world carbon levels in the future, says Wallace Broecker, one of the first climate scientists to predict global warming in the 1970s. The pioneer climate researcher of Columbia University foresees an international agreement—such as the 1987 Montreal Protocol, a worldwide treaty that phased out chlorofluorocarbons from aerosol cans that were boring a hole in the ozone layer.

Broecker believes companies that remove carbon from the ground in the form of fossil fuels—oil, natural gas and coal—should be taxed. The tax would go toward a global fund to sequester that carbon or turn it back into fuel using Lackner's technology, effectively closing the carbon cycle.

“This will be done, not before I die,” says Broecker, who is 81 years old. “But I would say in 30 or 40 years, it will be not only talked about but being done.”