Mining giant BHP has invested $6 million in Carbon Engineering, a company that has developed technology for direct CO2 capture from the atmosphere.
The size of the investment would indicate that there is something to this direct-from-the-air CO2 capture technology. However, from my outside position it strikes me as a strange thing to invest in.
Any separation technology must receive an input of energy from outside the system - the 2nd law of thermodynamics means you can’t get around that.
So any CO2 capture system requires energy from outside the plant. Their website says they use renewable electricity, but if they start selling this technology then other electricity sources could be used.
What puzzles me is this: capturing CO2 from the air (concentration ~400ppm) vs from flue gas (over 100,000 ppm). Energy requirements go up the more times you need to concentrate something. So going to (say) 90% CO2 purity, you’re looking at ~2250 times for atmospheric capture vs ~9 times for flue gas capture. That’s going to require a lot of extra energy.
This difference should make direct air capture a much more expensive option than flue gas capture.
It’s not like we have a shortage of flue gas CO2 sources right now. I’m interested to know why you’d spend so much more on energy to do CO2 capture like this vs a more conventional flue gas capture plant. The economics of this process will be very interesting.
An article by Carbon Engineering’s patent author David Keith estimates a levelised cost of CO2 capture for this technology at USD 94-232 per tonne of CO2 captured.
This is a very high capture cost compared to so many available alternatives for carbon dioxide abatement. Energy efficiency projects, by comparison, often yield very low or negative (i.e. they pay you) costs for abatement. Fuel switching is often much cheaper, as are renewable energy projects.
At this point I’m left wondering about BHP’s motivations for this investment. Carbon Engineering won’t be selling many of these plants in the absence of a very very high carbon price - something that’s unlikely to emerge in the foreseeable future.
A few skeptical commenters on my LinkedIn post on this topic believe this investment is straight-up greenwashing - a way for BHP to give the appearance of dealing with their GHG emissions with a tiny investment. For context, this AUD 6 million (USD 4.2 million) investment is a tiny fraction of the USD 2.02 billion net profit it made last year.
Time will tell. Maybe Carbon Engineering have some plans to drop this technology’s operating costs. I’d love to hear from you if you know more about this.