New technology extracts CO2 from the atmosphere

It is set to be a game-changer for CO₂ capture: The newly developed pilot plant, the size of a truck container, extracts 50 tons of CO₂ from the atmosphere per year – and does so with a record low energy requirement of under 2.000 kilowatt-hours per ton. This new pilot plant, the Austrian Pilot Unit 1 (APU1), has been commissioned recently and is now being successively developed and scaled up. The whole project was initiated and financed by the initiative of the American investor Peter Relan, founder and president of the Dharma Karma Foundation.  

The idea of filtering harmful CO₂ from the surrounding air is not new. However, this new technological approach to extract CO₂ directly from the air focuses on minimizing the plant’s energy consumption. A compact module was created, which can be flexibly used in the future: individual units can be used by smaller companies or private initiatives, while larger companies could combine multiple modules into a large-scale plant. The next step is to establish a 1,000-tonne facility, which could evolve into commercial-scale modules.

Key Question for the Future of Climate

It is clear: CO₂ capture does not mean, that in the future we can carelessly emit CO₂ into the atmosphere. Reducing CO₂ emissions is unavoidable. However, even that won’t be enough. In addition, we will also have to retrieve CO₂ that has already entered the atmosphere. In current climate models, this CO₂ capture is already factored in, even though the technology for it is not yet available on the market. If it is not possible to remove CO₂ from the atmosphere on a large scale over the next few decades, climate change will develop much more negatively than previously predicted. This makes CO₂ capture a central issue for our climate future.

Fine-Grained Filter Material Binds CO₂

The idea behind the process is quickly explained. Certain materials, such as amines, can bind CO₂ from the air. The material is used in a finely granulated form bound to a solid, and air is pumped through it, almost completely removing CO₂. At some point, the filter material becomes saturated, and the bound CO₂ must be removed from the filter material and stored elsewhere. To do this, the filter material must be heated – a significant portion of the plant’s total energy requirement is allocated to this step. At elevated temperature, the bound CO₂ is released from the material, after which the regenerated material can filter CO₂ from the air again.

Currently, both steps – filtering and regenerating – take place in the same location, but this results in energy loss, because not only the filter material but also the surrounding containers and technical equipment are heated during each cycle and then have to cool down again. To stop this energy loss a technique, in which the filter material is automatically transported between a hot and a cold container, was developed.

Two-Zones Process Saves Energy

The containers where the actual filtering process occurs never need to reach high temperatures. Once the material is saturated, it is transported to the regenerator via a specially developed transport system – only there is heating necessary. Additionally, through a sophisticated arrangement of multiple regenerators, an extremely energy-efficient regeneration of the filter material can be achieved. Afterward, the filter material is returned. This trick results in an energy balance that outperforms other systems. Less than 2.000 kWh are needed to capture one ton of CO₂.

If heat is supplied from other low grade heat sources below 100 °C, the APU1 can naturally become even more efficient. It is ideally suited for coupling with energy plants that generate heat. Today, low-temperature waste heat, as required by such a system, is often not utilized and is simply released into the environment as waste heat.

This is precisely how the research team and investor believe this technology will become economically viable: The idea is not necessarily to build a large, centralized CO₂ capture facility but rather to offer a compact, scalable technology that can be installed based on individual needs – similar to how customized photovoltaic systems are installed today.

The TU Wien, designed the process, first prototypes and provided it’s previous expertise and lab scale test results for the current unit. The U.S. based startup DAClab and the Austrian based startup DACworx picked up this knowledge to design and build the Austrian Pilot Unit 1 (APU1) for direct air capture, as it was presented at last. Together with TU Wien employees the pilot plant has been commissioned recently.