Wednesday, October 15, 2008

Air capture of CO2?

Fascinating if true:
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, using near-commercial technology.

In research conducted at the U of C, Keith and a team of researchers showed it is possible to reduce carbon dioxide (CO2) – the main greenhouse gas that contributes to global warming – using a relatively simple machine that can capture the trace amount of CO2 present in the air at any place on the planet.

"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.
The article says that capturing a tonne of CO2 would cost just 100 kwh of electricity, meaning that the energy costs should be something like $10-15/tonne of CO2. A cap-and-trade system with a floor price of $40/tonne would work rather nicely in this case.

There's still the question of what to to with megatonnes of CO2. I'm definitely a sequestration skeptic, but there's multiple forms of solid carbon that could theoretically preserve the carbon underground or underwater for millenia without risk of it coming back.


adam said...

couldn't we use it to make the carbon nanotubes that will power our electric cars?

I don't really know the manufacturing processes, maybe it's not practical. But given the multiple potential uses for carbon these days...

Gar said...

Hmm - the carbon balance certainly sounds good. 100 kWh produced by coal puts a bit over 21 pounds of CO2 into the air. If that can remove a metric ton, that is one heck of net CO2 removal. Even better if it is from natural gas, wind or sun. Not going to endorse this, but certainly worth looking into further. For example, I'd like know how solid these figures are.

Gar said...

Should have read the article before commenting. Lab demo, not prototype. And though electricity costs are low, capital costs appear to be high. Displacing fossil fuels still looks to be cheaper than capturing carbon from the air.

However we should be funding this type of research, because there are two places where it can play a serious role.

1) Once we get at or near zero emissions we will still need stuff of this type to go GHG negative which Hansen seems to think we will need to do. Given the climate disruption that has already taken place, improved forestry and agriculture may not be enough to make up for increased forest fires and feed releases from soil and ocean. So in the long run this stuff will almost certainly be needed.

In the medium run, while reducing emisison may be cheaper than capture up to a point, it seems likely that onces we reduce fossil fuel use per unit of GDP by between 80% and 95%, capture may indeed prove cheaper than the remaining 5% to 15%.