Climeworks is hoping to make direct air capture (DAC) a commercial success.
Eric Johnson of Chemistryworld.com reports:
Companies are already implementing carbon capture technologies to mitigate their carbon emissions by scrubbing CO2 from concentrated streams such as flue gases. However, there is growing evidence that ‘carbon dioxide removal’ technologies that can reduce CO2 levels in the ambient atmosphere (currently around 0.04%) will also be needed if countries hope to meet the Paris Climate agreement target of 2°C warming.2
But while there is an environmental case for DAC, the economic case is much weaker. Although the CO2 it produces would be a saleable commodity, a pro-DAC study published in 2011 by the American Physical Society3 concluded that CO2 from DAC would cost at least $600 per tonne. That is nearly triple the going market rate for small quantities. Yet a Swiss startup called Climeworks thinks it can turn the corner on DAC economics, and aims to prove it with its new plant 30km southeast of Zurich.
Since going onstream in early June, the 900tonne/year direct air capture (DAC) plant from Climeworks has already cracked the $600 barrier says Valentin Gutknecht, Climeworks’s head of business development. At this price, it is competitive in remote locations, where CO2 for carbonated drinks and greenhouses must be trucked over long distances. Unlike industrial sources of carbon dioxide, air is everywhere, so a DAC plant can be built almost anywhere.
The plant extracts ambient CO2 by blowing air across filters charged with an amine sorbent. After about two hours, the filters are saturated, and the CO2 is desorbed by heating. Climeworks’s competitiveness rests on its ability to use low-grade exhaust heat of around 100°C for this process. Gutknecht points out this is widely available and cheap – in Climeworks’s case, it comes from a neighbouring municipal-waste incinerator – and accounts for about 80% of the process energy. Most of the rest is consumed in driving the intake fans.