The Swiss start-up Climeworks is developing a system that extracts CO2 out of the air for greenhouse horticulture purposes. The system will be tested during a three-year pilot and should be able to capture some 2 to 3 tons of CO2 on a daily basis. This will be piped to a nearby greenhouse to boost the growth of lettuce, cucumbers and tomatoes, according to New Scientist magazine.

The system, called Direct Air Capture (DAC), captures air in closed spaces, such as submarines and space capsules. The captured ambient air is pushed through a fibrous sponge-like filter material that has been impregnated with chemicals derived from ammonia. Once the filter is saturated, the gas will be released by warming it with the heat which is in this case generated by a nearby municipal waste incineration plant. The CO2 thus released is then piped to a 4-hectare greenhouse.

High costs

According to calculations made by the American Physical Society the cost of capturing CO2 on this scale would be 600 dollars a ton, says Climeworks COO Dominique Kronenberg. The Swiss start-up also expects to equal that and eventually get costs down well below that. At that price, taking C02 out of the air is more expensive than removing it from the flue gases of industrial facilities and power plants, where the gas is up to 300 times more concentrated.

Location independent

Despite the high price, Kronenberg notes the many advantages to the DAC process. ‘The advantage of taking it out of the ambient air is that it can be done no matter where you are on the planet. We are not dependent on a source of CO2, so neither will we need to make high costs to transport the CO2 to the greenhouses.’ Climeworks will be using funding from the Swiss Federal Office of Energy to fine-tune the system. The objective of the three-year pilot period is to make the system run more cheaply and efficiently and, in doing so, enable the company to gain a solid foot on the market.