Article Summary: ' Scrubbing the Skies'

Article: Scrubbing the Skies

Publisher: The Economist

Date: March 5^th 2009

URL: http://www.economist.com/research/articlesbysubject/displaystory.cfm?subjectid=348924&story_id=13174375

Environmentally oriented technology today is designed to emit as little carbon dioxide as possible in order to reduce the level of man-made CO₂ in the atmosphere. Countries have made ambitious pledges to reduce emissions by 80, 90 or even 100% in the years to come. However, a new technology, still in the experimental phase, is potentially a much simpler way of reducing the CO₂ in the atmosphere: air capture machines that remove CO₂ from the air.

Several designs of these air machines are being developed that all follow the same basic principle. The idea behind these machines is that air is to come in contact with a sorbent material which binds chemically to carbon dioxide. One version of air capturing machinery, designed by a team led by Dr. David Keith (University of Calgary) is towers, several meters tall, in which a liquid sorbent is sprayed to make a fine mist. This increases the sorbents efficiency, since it increases its surface area. Air is wafted through these towers, the CO2 is absorbed and the sorbent drains out of the tower as a liquid. The CO2 would be removed, either by a series of chemical reactions or by applying an electric current, and then it would be compressed to liquid form. The sorbent would be recycled. In another version of this technology, designed by Dr. Lackner (professor of geophysics at Columbia University), a solid sorbent is used; thin sheets of material coated with proprietary chemicals would be used. Carbon dioxide in the air is trapped by the sheets and is then absorbed by liquid chemicals. The CO2 is removed from the chemicals by heat.

However, certain technical, financial and political objections have to be overcome in order for the technology to go anywhere. Powering these machines requires electricity, which in turn produces carbon dioxide emissions. If the machinery emits more carbon dioxide than it processes, the technology would be obsolete. Tests revealed that Dr. Keith’s prototype needed 100 kilowatt-hours of electricity, which was generated by a coal-fired power station, to capture one ton of CO2; overall, 3.5% of the amount of carbon dioxide removed by the machine was added to the atmosphere. If a cleaner power source was used, this percentage could be lessened further. Therefore, the technology effectively carries out its purpose. Another issue is the cost of these machines relative to other options for carbon reduction that are currently available. Selling the technology to companies that require CO2 would make it profitable. In addition, the CO2 itself could be sold, since many businesses need it. However, the price of ‘pollution permits’ (allow for emission of 1 ton of CO2) is currently at below $10, while the price of the CO2 produced by this technology is at $200. Only when this new technology becomes more economically attractive will it be preferable to just buying the right to pollute. Finally, this new technology could eliminate the incentive to invest time and money into other environmentally friendly technologies. However, they two technologies could be combined. For example, excess energy from wind farms could be used to power the air capture plants. Overall, this technology, though still in the stages of experimentation, could be the solution to the world’s carbon emission problems.