Klaus Lackner, director of the Lenfest Center for Sustainable Energy at Columbia University, has come up with a technique that he thinks could solve the problem. Lackner has designed an artificial tree that passively soaks up carbon dioxide from the air using “leaves” that are 1,000 times more efficient than true leaves that use photosynthesis.
"We don't need to expose the leaves to sunlight for photosynthesis like a real tree does," Lackner explains. "So our leaves can be much more closely spaced and overlapped – even configured in a honeycomb formation to make them more efficient."
The leaves look like sheets of papery plastic and are coated in a resin that contains sodium carbonate, which pulls carbon dioxide out of the air and stores it as a bicarbonate (baking soda) on the leaf. To remove the carbon dioxide, the leaves are rinsed in water vapour and can dry naturally in the wind, soaking up more carbon dioxide.
Lackner calculates that his tree can remove one tonne of carbon dioxide a day. Ten million of these trees could remove 3.6 billion tonnes of carbon dioxide a year – equivalent to about 10% of our global annual carbon dioxide emissions. "Our total emissions could be removed with 100 million trees," he says, "whereas we would need 1,000 times that in real trees to have the same effect."
If the trees were mass produced they would each initially cost around $20,000 (then falling as production takes over), just below the price of the average family car in the United States, he says, pointing out that 70 million cars are produced each year. And each would fit on a truck to be positioned at sites around the world. "The great thing about the atmosphere is it's a good mixer, so carbon dioxide produced in an American city can be removed in Oman," he says.
Source: BBC's "Sucking CO2 from the skies with artificial trees" http://www.bbc.com/future/story/20121004-fake-trees-to-clean-the-skies