The Audi idea: capture the CO2 from the air and transform it into rock

A fascinating experimentation by the German asa: a plant in Iceland that extracts carbon dioxide and stores it underground

Among the numerous fronts of sustainable mobility on which Audi is committed, one of the most important is that linked to the reduction of the amount of carbon dioxide found in the atmosphere. A priority for Audi, which aims to become carbon neutral by 2050, with a very important intermediate goal: to produce in factories that do not pollute at all. This year, after the one in Brussels, it was the turn of the Gyor site (Hungary) to receive carbon neutral certification, largely obtained thanks to the largest rooftop photovoltaic system in Europe. Made in collaboration with E.ON, it is installed on the roof of the two logistics centers and occupies a total area of ​​160 thousand square meters, with 36,400 solar cells and a peak power of 12 megawatts. Since the beginning of 2020 the Magyar plant uses exclusively renewable sources: 70% of the needs are met by geothermal energy, while the remaining portion is entrusted to biogas.

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STARTUP

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Audi’s projects to be non-impacting on the climate are numerous. The most fascinating, developed in collaboration with the Swiss startup Climeworks, is to convert carbon dioxide into rock. In short, it involves capturing the air from the environment, filtering the CO2 and transporting the latter underground, where through a natural process it is transformed into rock. The trial was started in Iceland, where Climeworks built a plant that filters 4,000 tons of carbon dioxide a year and mineralizes it underground. The first advantage? Part of that CO2, a thousand tons, are counted in Audi’s sustainability report.

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PURE CHEMISTRY

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The process isn’t straightforward. To begin with, the air is sucked in and conveyed into a collector. Here it passes through a selective filter that captures and fixes the CO2 thanks to the material it is made of, capable of accumulating gaseous substances on its surface. When the filter is saturated, it is heated to 100 ° C using the waste heat produced by a nearby geothermal plant, causing the release of carbon dioxide molecules. At this point, the air deprived of CO2 returns to the atmosphere, while the accumulated carbon dioxide is carried 2,000 meters underground, where natural processes mineralize it. Transportation below the earth’s surface takes place by means of water from the Hellisheiði power plant. Deep down there is a natural reaction between the CO2 molecules and the basaltic rock, and it is this reaction that activates the process that converts CO2 into carbonates. A slow process, we are talking about several years, but the storage underground allows you to immediately remove the CO2 from the air. Once the transport is completed, the water returns to the geothermal plant’s cycle.

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IDEAL PLACE

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The plant designed by the Swiss works 24 hours a day, 7 days a week. To obtain the same filtering result in a natural way (as we have already said: 4,000 tons of CO2 a year) 80,000 trees would be needed. The technology developed by Climeworks stores in the subsoil, effectively and permanently, 90% of the CO2 filtered from the air. And it is a scalable and reproducible system for large quantities: it therefore offers enormous potential for the future. It is no surprise that the project is being studied in Iceland: an ideal place because its volcanic origin makes it one of the most powerful geothermal areas on Earth. This means that large amounts of energy and heat from the planet can be converted into electricity in an economical and virtually CO2-neutral way. In addition, Icelandic rock has the ideal composition to store large quantities of carbon dioxide. Waiting to confirm the validity of the project, Audi and the Swiss startup are not standing still: they are studying new heat exchangers.

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