I wrote the comment below in response to another article, but it is applicable here. I should note that the technology to convert CO2 to say hydrocarbons is well known (and my current work is on making it economically interesting), my issue is with trying to extract CO2 from the atmosphere, which is very inefficient.
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This is actually a very bad idea and a complete waste of money which should have been used for other projects. It reminds me of another bad idea, which just will not die - extracting water from air by cooling it.
Right now, we have several technologies ready to go. Starting with the most cost-effective, and omitting the "use less" scenarios:
1. Replacement of fossil fuel power plants with carbon free electricity such as wind and solar power (also geothermal, where possible and nuclear, where palatable). Cost per tonne of CO2 saved: less than zero for about 30% of current generation, and "very low" for a good portion of the remainder.
2. Sequestration of concentrated CO2 streams, such as those produced in natural gas processing. Cost: $20-$40 per tonne.
3. Biosequestration, ie tree planting. Cost varies greatly, maybe $15-$50 per tonne.
The approaches above are the only ones that are actually used in the industry today, but there is plenty of room to do more. The approaches below are considered to be economically prohibitive, and AFAIK are not in use:
4. Post-combustion carbon capture: Scrubbing the CO2 from exhaust gases of power plants etc, where the CO2 concentration is 10-20%. Cost: $50-100/tonne, PLUS the cost of sequestration, as above.
5. Pre-combustion carbon capture: here, the carbon is removed from the fuel and sequestered, and only the hydrogen is burned. Cost: $80-150/tonne, but sequestration cost is low.
and then we have:
6. Removal of CO2 from the atmosphere. The article says the cost may be "under $100/tonne", but the serious estimates I have seen are circa $500/tonne. Consider that the CO2 concentration in air is around 0.04%, cf post combustion concentrations of 10-20%. Regardless of the advances in technology, this will never be as cheap as post-combustion carbon capture, which is essentially the same process but with 250 times less throughput.