I just bought and read the Kindle edition of the short book by Marc Gunther “Suck it up – How capturing carbon from air can help solve the climate crisis”.
The author discusses the sorry state of climate change mitigation measures and several other geoengineering proposals. Then he describes some of the startup companies active in the field of capturing CO2 from the air.
That is not difficult to do. For example, this kind of technology has been deployed for decades on submarines to deal with the CO2 exhaled by crew members.
The only trick is to do it cheap enough, and to scale it up to the necessary levels.
By chance, I just had read this article by Umair Irfan in Scientific American (2011), which is rather critical of these concepts (“too expensive to be practical”).
I learned a couple of things worth noting from Gunther’s book.
For starters, the various ideas of shading the earth are actually extremely cheap in comparison with reducing CO2 emissions. Good to know. It may become necessary to fall back on this kind of scheme if CO2 emission reduction efforts keep failing.
Also, CO2 is sold on the market at prices of up to $200 a ton. The largest market for that is enhanced oil recovery, where the CO2 is used to squeeze out oil from the ground. Not exactly helpful from a climate perspective, but the oil recovered in this way is actually less dirty than conventional oil, since the CO2 used in the process remains in the ground. There are more than 100 enhanced oil recovery projects, which pay between $20 and $40 per ton for CO2.
The whole sector is still tiny. Some of the startups involved have built first demonstration plants. One of the main problems (also discussed in the Scientific American article cited above) is energy cost. It obviously doesn’t make sense from a climate point of view to put more CO2 in the atmosphere to generate the energy necessary than is removed in the sucking process.
But those problems disappear once basically unlimited renewable energy from the deserts is available in a century or two. We might see some serious CO2 sucking already fifty years from now.
Anybody interested in getting a look at the present state of this nascent industry is well advised to read this book. I enjoyed doing so and learned a lot.