Calgary team shows how to scrub CO2 from the air
University of Calgary climate change researchers say they are close to figuring out how to commercialize the capture of carbon dioxide directly from the air with a simple system that could be set up anywhere in the world.
If they can make it work, it would allow greenhouse gas to be removed from ambient air and reduce the effect of emissions from transportation sources such as cars and airplanes.
"That's the excitement about it. It's a tool for dealing with diffuse CO2 emissions from transportation that account for roughly half of emissions," physicist and climate change scientist David Keith said Tuesday in a phone interview from his Calgary office.
That's important given how conventional systems for capturing CO2 work. Most involve installing "scrubbing" equipment at, for example, a coal-fired power plant to capture carbon dioxide produced during the burning of coal. But a system that can take CO2 out of ambient air is attractive because cars and airplanes aren't equipped with such scrubbers.
"You could do it wherever labour or capital costs are the cheapest and wherever you can best put the CO2," said Keith.
Over the summer, Keith and his team conducted an outdoor test of its seven-metre CO2 capture tower at the University of Calgary sports stadium.
The tower acts as a scrubber, with sodium hydroxide, also known as caustic soda, reacting with air blown into its base. A metal honeycomb system inside the tower slows down the flow of caustic soda, allowing it to efficiently scrub CO2.
While Keith said the technology isn't new — it's been used since the 1950s in industrial processes that call for carbon dioxide-free air — he believes his team has surmounted one of the two biggest obstacles to CO2 capture.
For the system to be effective, it must remove more carbon dioxide from the air than it emits as a byproduct of the energy used to run the scrubber. This summer's experiment showed that can be done, said Keith.
He estimates that if the electricity used to run the ambient air scrubber were to come from a coal-fired power plant — a heavy emitter of CO2 — he could capture 10 times more CO2 than the coal plant emitted.
The second catch, of course, is finding somewhere to store the CO2.
While some scientists have suggested storing it deep underground or at the bottom of the ocean, it's not yet clear how effective or affordable that would be on a large scale.
Marlo Raynolds, executive director of the Pembina Institute, an Alberta-based environmental think tank, said Keith's system merits the research effort.
"But while we advance technology like this, we need to deploy current technology that we know works now — conservation, hybrid vehicles. And we have to have the right policies in place to promote that, such as a price on carbon," Raynolds said.
"I think David Keith would be the first to admit it will be a long time before we see these things on street corners."
Indeed, Keith stresses that point, saying, "The steps between this and building an engineering company that gets a lot of smart people working on this project are pretty big."
Other researchers — most notably at Columbia University in New York City and Lawrence Livermore National Laboratory in California — are also working on ambient air scrubbing technology, and Keith said he'd like to investigate potential commercial partnerships with them.
Certainly there is incentive beyond doing the environment a good turn.
Richard Branson, head of Virgin Group, has made a standing offer of $25 million US for anyone who can come up with a system to remove the equivalent of one billion tonnes of carbon dioxide or more every year from the atmosphere for at least a decade.
The University of Calgary's scrubber tower experiment will be featured in January on an episode of Discovery Channel's new Project Earth series.