Regionalwerke Baden: “The pilot project is paving the way for Swiss bioenergy with CO₂ recovery (‘BECCUS’)”

Please could you start by giving us an overview of ‘CO2 Energie AG’ and the services it offers in the energy sector.
Lehmann: CO2 Energie AG is a joint venture between the two companies ‘Regionalwerke AG Baden’ (RWB) and ‘Recycling Energie AG’. The company was founded in 2021 with the aim of building the CO₂ liquefaction plant at the Nesselnbach biogas plant site.

You yourself describe the biogas plant installed by “CO2 Energie AG” in Nesselnbach, Switzerland, as a “pioneering project in Europe”. How do biogas plants generally work?
Lehmann: “Recycling Energie AG” operates a biogas plant in Nesselnbach. This means that food waste is collected and processed. This is then fermented on-site, producing raw biogas. Regionalwerke AG Baden (RWB) operates a biogas processing plant at the site, which processes the raw biogas. The end product, biomethane, can then be fed into the gas grid.

In addition, ‘CO2 Energie AG’ has built a CO₂ liquefaction plant; this means that the CO₂ – which until now would have escaped into the atmosphere and is separated during the biogas processing – is captured there and liquefied for various industrial applications. In technical terms, this is known as ‘Bioenergy Carbon Capture & Utilisation (BECCU)’.

What makes this ‘pioneering plant’ in Nesselnbach so special? Can you describe the utilisation process? Lehmann: The raw biogas, which consists of 60% methane and 40% CO₂, is processed and fed into the local gas network. Before being fed into the grid, the raw gas is pre-cleaned using activated carbon filters and then compressed to approx. 16–17 bar. The dry, compressed gas is then passed through a membrane to separate it into CH₄ (methane) and CO₂ molecules. This end product must consist of at least 96% methane gas. Until now, the CO₂ has been released into the atmosphere.

With the new ‘carbon capture’ process, the CO₂ is now captured, processed, purified, liquefied and then stored in tanks. With the new plant, around 90% of the CO₂ produced can be utilised. That amounts to up to 3,000 tonnes annually. What makes this special is that the liquid CO₂ is so pure after the process that it is ‘food-grade’. Our customer for the CO₂ is the company ‘Messer Schweiz AG’ in Lenzburg. The CO₂ is used for various applications, primarily in the food industry. It is interesting to note that the end product – food-grade CO₂ – is produced from the initial material of food waste.

The plant is a joint project with ‘Hitachi Zosen Inova’ and ‘ASCO Kohlensäure AG’ from Romanshorn, Switzerland. What does the collaboration look like?
Lehmann: CO₂ Energie AG ordered the plant as a complete system from Hitachi Zosen Inova. ASCO was selected by Hitachi Zosen Inova for the CO₂ liquefaction process. The Nesselnbach project is the first plant of its kind in Switzerland and a very good example of how CO₂ can be effectively captured and reused.

There is a great need to reduce CO₂ emissions worldwide. Is the Nesselnbach project a ‘model case’ specifically for the energy industry, or do you see other approaches?
Lehmann: There are various promising approaches. ‘Carbon Capture & Storage (CCS)’ is particularly interesting in this regard. There are various applications for permanently ‘storing’ the recovered CO₂, such as in recycled concrete or in long-term storage facilities like depleted natural gas or oil fields.

Are further biogas plants with CO₂ recovery planned at Regionalwerke Baden?
Lehmann: Absolutely! We are always on the lookout for further CO₂ sources so that we can plan, build and operate more plants. It is essential for us to replicate the expertise we have built up in this area.

How has the industry reacted to your project? It would be desirable, in terms of ‘our’ carbon footprint, to see numerous imitators.
Lehmann: I believe this pilot project is an important door-opener for further projects. The entire industry, particularly the biogas industry, can see that it is possible to build such a plant and operate it profitably.

The industry has certainly reacted with great interest. We are receiving many enquiries about site visits. What really matters is that such a plant is located in Switzerland and that people can find out how it works on site. We have experienced first-hand how difficult planning is without an existing plant from which one can benefit from a certain transfer of knowledge.

If there are no CO₂ buyers for future biogas projects, is ‘Carbon Capture & Storage’ (CCS) an idea you have already considered?
Lehmann: The idea of CCS, or ‘Carbon Capture & Storage’, is certainly of interest to us. We intend to use the know-how we have gained to operate more plants in the future. We also have other biogas treatment plants where the CO₂ is still released into the atmosphere. At some point, CO₂ consumption or uptake in Switzerland will stagnate. Then we will certainly have to consider how to deal with the surplus CO₂. That is why we are definitely examining various scenarios here.

Managing Director of Regionalwerke AG Baden
, Philippe Lehmann
 

About Regionalwerke AG Baden

Regionalwerke AG Baden supplies the town of Baden and the surrounding region with energy and water. In addition to a secure and reliable energy supply, RWB offers its customers both within and outside its supply area a wide range of services in the field of energy solutions. RWB supports its customers personally and with full commitment.

About Recycling Energie AG

Recycling Energie AG operates Switzerland’s largest plant for producing raw gas from food scraps and food waste. It produces around 1,800 m³ of biogas per hour. Two-thirds of this is converted into green electricity, which supplies around 5,000 households. The remaining third is processed by RWB and fed into its natural gas network as biogas. This gas can be used to heat around 2,500 households. In addition, Recycling Energie AG produces approximately three million litres of biofuel every year.