Climeworks, a Swiss company, has built a commercial plant to extract carbon dioxide from the air.

Currently the cost of the process, $600 per tonne of CO2, is prohibitively expensive. Climeworks recovers part of this cost by selling the CO2 to a nearby fruit and vegetable grower for use in its greenhouse.

The company believes that it can get the cost down to $100 per tonne of CO2 by 2025 or 2030 and aims to be capturing 1% of global CO2 emissions each year by 2025.

The Climeworks technology consists of a series of three, stacked, shipping container-sized units, each of which contains six CO2 filters. A large hot water storage tank sits alongside, along with two further containers housing control equipment.

Fans blow ambient air over the capture filters, which trap CO2 and water. These are later released with heat. Water is the only by-product of the process. The machinery is capable of capturing 900 tonnes of CO2 per year.