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Scientists propose selling CO2 absorbed by carbon capture technology to the owners of greenhouses, who routinely buy CO2 that plants absorb. 

Recycling CO2 could figure in the zero sum solution to climate change

by Monika Wnuk
Oct 24, 2013



One of Lachner’s designs for an "articficial tree," the carbon scrubber he developed to absorb CO2 from the air. Each scrubber captures one ton of CO2,  the amount emitted by 75 cars burning about 1.3 gallons of gasoline.



Thinner plastic filters than this older model are housed inside of the main carousel of a scrubber. When wind blows through the scrubber’s plastic filters, they absorb CO2 until saturated, at which point they are lowered into vacuum chambers to be cleaned before resurfacing.


MEDILL photo

Columbia University geophysicist Klaus Lackner is developing carbon capture technology, demonstrating viability with a prototype unit. He spoke at this month’s Comer Abrupt Climate Conference.

Capturing and storing the 29 billion tons of carbon dioxide emitted annually from burning fossil fuels could help clamp a lid on climate change. At the Comer Abrupt Climate Change Conference this month in Wisconsin, scientists shifted the focus away from capturing and storing CO2 and toward recycling it.

“If you want to store CO2, one of the problems is you end up storing a lot of CO2. I think over this next century, we are likely to produce an amount of CO2 which is comparable to the [amount of]water in Lake Michigan” if we pulled it all out of the air, Columbia University geophysicist Klaus Lackner said at the conference.

But the big challenge for Lackner and the planet is to capture CO2, a greenhouse gas that spread through the atmosphere, holds in heat and is forcing global warming.

Lake Michigan, which holds 5 trillion tons of water, sets a relatable scope for just how much CO2 would need to be collected to keep levels where we are now in terms of climate change. And scope is central to the feasibility of Lackner’s carbon capture technology.

At the core of the technology is what Lackner calls an “artificial tree,” a carbon scrubber that could capture one ton of CO2 a day, equivalent to the CO2 emitted by 75 cars after they burn a little more than a gallon of gas. The scrubber’s main visible feature is a carousel housing plastic filters that resemble pipe cleaners. When wind blows through the scrubber’s plastic filters, they absorb CO2 until saturated, at which point they are lowered into vacuum chambers to be cleaned before resurfacing.

Rather than storing the CO2 that’s left behind underground, scientists are coming up with various ways to recycle it. One of these is selling CO2 to greenhouses.

“In Rotterdam, [greenhouse owners] pay 100 euros for a ton of CO2 to inject into a greenhouse,” Lackner said.

A Johnson brand CO2 generator, which the company’s website says can provide up to 1,500 parts per million of CO2 per unit in a 24-by-200-foot greenhouse, can sell for $50 to $600.

Although selling CO2 to greenhouses would recycle it in an inexpensive way that wouldn’t require turning the gas into a liquid, Lackner said that’s just one small way to recycle CO2.

Converting CO2 - an emission from gasoline back into gasoline - could have a much bigger impact even than investing in battery-powered electric cars.

“I think an electric car is probably an advance over an internal combustion engine, but it’s not clear that an electric car has to run on batteries because batteries are very inefficient in storing energy” right now, Lackner said.

Converting CO2 to a liquid fuel could improve upon the tank efficiency of hybrid cars, Lackner suggested.

“If your battery car could get 200 to 300 miles on a tank, this car can get several thousand miles on a tank,” he said.

The process of converting CO2 emissions to a liquid fuel is nothing new. Short on resources, the Germans experimented with it in the 1920s and actually implemented the process during World War II.

In 2007, chemists at the University of California, San Diego demonstrated how sunlight could be used to transform a greenhouse gas into a wide range of useful products, including gasoline.

Their study showed that light absorbed and converted into electricity could drive a reaction that converts carbon dioxide into carbon monoxide and oxygen. Carbon monoxide is a key ingredient in synthetic fuels, including gasoline.

Clifford Kubiak, a chemist who worked on the study, told the university that although a much larger scale operation would be needed to implement the conversion process globally, his results show both that recycled CO2 can power machines cleanly and that it can replace fossil fiels that are being used to make plastics daily.

For Kubiak’s technology to catch on, Lackner’s has to first be implemented on a global scale and this could take 20-30 years, although that is common for a new technology, he said.

“If you think about cars in 1900, you had practically none. If you look at a picture of New York City in 1925, the city was full of cars. That 25 years was apparently enough to get from a pre-car society to a society that had fully embraced cars,” Lackner said. “The 20-30 years is sort a typical time frame to get things going,” he added.

Lackner has spent a decade so far working on developing his carbon scrubbing technology. In 2004, he co-founded Kilimanjaro Energy, a direct air capture company, with seed money from the late Gary Comer, the entrepreneur and philanthropist who founded Lands’ End.

In 2006, he presented Comer with a vial of pure CO2 he had captured. Since then, Lackner has developed a prototype and a price range. He said that the initial cost of extracting a ton of CO2 from the air could be between $100 and $150, but he is optimistic that the price could drop to just $30 per ton of CO2 once things get rolling on a larger scale.

“Solving this problem is never going to be small. If you’re talking $30 per ton of CO2, it will not break the bank. Economies can afford that,” he said.

Wallace Broecker, Columbia University climate researcher Wallace Broecker, who helps coordinate the Comer Conference, said he is surprised that there’s been a delay in investment in the technology.

“The total amount of money that’s been spent on it in 10 years is no more than $25 million. That’s what A-Rod makes for the Yankees in one season. There’s something wrong” Broecker said.

Both Broecker and Lackner agreed that reducing the CO2 we emit daily to zero is necessary for carbon capture to make a difference. However, uncertainties in CO2 mitigation in the next few decades make it even more important to invest in carbon capture now.

“This is not an overnight fix, but it allows you to actually go backward" in terms of reducing CO2 levels and capping global warming, Lackner said.