Researchers at Carbon Engineering in Calgary, Canada, have been operating a pilot CO2-extraction plant in British Columbia since 2015. They are using direct air capture. Depending on a variety of design options and economic assumptions, the cost of pulling a tonne of CO2 from the atmosphere ranges between US$94 and $232. The last comprehensive analysis of the technology, conducted by the American Physical Society in 2011, estimated that it would cost $600 per tonne.
Carbon Engineering’s blows air through towers that have a solution of potassium hydroxide, which reacts with CO2 to make potassium carbonate. The calcium carbonate pellet can be heated to release the CO2. The CO2 can be pressurized and put into a pipeline and disposed of underground. They will use the gas to make synthetic, low-carbon fuels. They can produce fuel at a cost of about $1 per liter. When the air-capture plant is optimized for fuel production, they were able to bring costs down to as low as $94 per tonne of CO2.
The Swiss company Climeworks has a 900 ton of CO2 per year commercial facility that has been operating since 2017. Climeworks expect to get the cost below $100 per tonne in 5-10 years as operations ramp up.