Carbon from air

University of Calgary climate change scientist David Keith and his team are working to efficiently capture the greenhouse gas carbon dioxide directly from the air.

In research conducted at the university, Keith and a team of researchers have showed that it is possible to reduce carbon dioxide (CO2) using a relatively simple machine.

‘At first thought, capturing CO2 from the air where it’s at a concentration of 0.04 per cent seems absurd, when we are just starting to do cost-effective capture at power plants where CO2 produced is at a concentration of more than 10 per cent,’ says Keith, Canada research chair in energy and environment.

‘But the thermodynamics suggests that air capture might only be a bit harder than capturing CO2 from power plants.

‘We are trying to turn that theory into engineering reality.’

Air capture is different than carbon capture and storage (CCS) technology.

CCS involves installing equipment at, for example, a coal-fired power plant to capture carbon dioxide produced during burning of the coal, and then pipelining this CO2 for permanent storage underground in a geological reservoir.

Air capture, on the other hand, uses technology that can capture the CO2 that is present in ambient air everywhere.

Keith and his team have apparently showed they can capture CO2 directly from the air with less than 100kW/h of electricity per tonne of carbon dioxide.

Their custom-built tower (see picture below) was able to capture the equivalent of about 20 tonnes per year of CO2 on a single square metre of scrubbing material – the average amount of emissions that one person produces each year in the North American-wide economy.

‘This means that if you used electricity from a coal-fired power plant, for every unit of electricity you used to operate the capture machine, you’d be capturing 10 times as much CO2 as the power plant emitted making that much electricity,’ Keith said.

The team has devised a way to apply a chemical process derived from the pulp and paper industry that cuts the energy cost of air capture in half, and has filed two provisional patents on their end-to-end air capture system.

The technology is still in its early stage, Keith said.

‘It now looks like we could capture CO2 from the air with an energy demand comparable to that needed for CO2 capture from conventional power plants, although costs will certainly be higher and there are many pitfalls along the path to commercialisation.’

Nevertheless, the relatively simple, reliable and scalable technology that Keith and his team have developed opens the door to building a commercial-scale plant.