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CO2 turns to rock: the Audi decarbonisation project

24.9.2020
CO2 turns to rock: the Audi decarbonisation project

Extracting CO2 from the air and transporting it underground, where it is turned to rock – that’s the aim of the innovative facility built by Climeworks in Iceland, which is planning to remove 4,000 metric tons of carbon dioxide a year from the atmosphere.

Reducing the carbon dioxide found in the atmosphere is a priority for Audi, which aims to become carbon neutral by 2050. To achieve this ambitious target, the brand with the four rings is adopting cutting-edge technologies and the most innovative climate-protecting solutions. One of these is the conversion process developed by Swiss start-up Climeworks – a company Audi is collaborating with. The project will extract air from the environment, filter the CO2 it contains, and transport it underground, where natural processes then will turn it into rock.

The project has been launched in Iceland, where Climeworks has built a facility that can filter 4,000 metric tons of carbon dioxide in the atmosphere per year and mineralise it underground. 1,000 tons of that will go towards improving Audi’s sustainability footprint.

A closed loop

The facility first draws in air from the environment and feeds it into a CO2 collector. It then passes through a special filter, which binds the CO2 in the air using adsorbent material – a material that can allow a gaseous substance to adhere to its surface through a chemical-physical process.

When this filter is saturated, it is heated to 100 degrees Celsius using waste heat from a nearby geothermal plant to release the carbon dioxide molecules. The air minus the CO2 is then returned to the atmosphere while the carbon dioxide is transported below the surface of the Earth, where natural processes mineralise it, leaving no remaining traces.

The power of water

Water from the Hellisheiði power plant flows through the facility and transports the carbon dioxide 2,000 meters underground. Once they are deep underground, the CO2 molecules react through natural mineralisation processes with the basalt rock and are converted to carbonates over a period of several years, thus permanently storing the CO2 underground. Meanwhile, the water returns to the cycle of the geothermal power plant.

Looking forward

The Climeworks facility will operate 24 hours a day, seven days a week, and will filter 4,000 metric tons of CO2 from the atmosphere each year. 80,000 trees would be needed to bind this amount naturally.

The direct air capture technology developed by Climeworks allows 90 percent of the CO2 filtered out of the air to be effectively and permanently stored underground. The system can also be scaled up to the megaton-per-year range and thus harbours great potential for the future.

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Geothermal energy

Iceland is one of several places on Earth offering the ideal conditions for this process. Its volcanic origin makes the country one of the world’s most potent geothermal regions.

This means that the Earth’s energy and heat can be converted to electricity cost-effectively and virtually CO2 neutrally. Furthermore, the rock in Iceland has the ideal composition for storing large amounts of carbon dioxide.

A holistic approach

The adsorption of carbon dioxide from the atmosphere is an innovative technology that can help us reach the Group’s climate targets. We are contributing to decarbonisation through our involvement in the Climeworks project, following our holistic approach”, says Hagen Seifert, Head of Sustainable Product Concepts at Audi.

Audi has been working with Climeworks since 2013. Two years ago, the companies built a facility in Hinwil, Switzerland, that filters CO2 from the air and provides it to the beverage industry, where it is converted to carbonic acid. Audi is also supporting the Swiss start-up with its technological know-how, such as for the development of new heat exchanger concepts.

SourceAUDI AG