From wastewater treatment to biogas production to carbon removal (CDR): How arabern valorizes its CO₂ volumes

Operating one of the largest wastewater treatment plants in Switzerland and also producing biogas – that's ara region bern's core competence. On top of that, arabern has been working with neustark to make profitable use of its CO₂ emissions volume. And is thus helping to scale permanent carbon dioxide removal (CDR).

Climate science underlines that, next to massively reducing emissions, removing carbon dioxide from the atmosphere is crucial in the race to net zero. Neustark has developed a solution to do exactly so: by capturing then mineralizing CO₂ in mineral waste streams such as demolished concrete.

To capture CO₂, we work with biogas plants such as ara region bern ag (arabern). Arabern is one of the largest public wastewater treatment plants in Switzerland and a major biogas producer. An unusual combination, because in addition to treating wastewater, arabern also recycles biomass. 

This is exactly where neustark comes into play: We help our partners like arabern by valorizing their emissions volumes. CO₂ capture and removal offers the opportunity to make use of the CO₂ that is produced during biogas upgrading processes and thus generate an additional source of income. 

Find out how this business model works from the perspective of our partners...

How arabern utilizes their biogenic CO₂ to contribute to CDR

Adrian Schuler is the managing director of ara region bern ag. Neustark has been working closely with him and his team over the past three years. Arabern was our first CO₂ capture site and pilot project. Kapok, as we named the site internally, can capture and liquefy up to 2,000 tons of CO₂ per year. However, this by far does not correspond to the total amount of CO₂ that is annually produced as a by-product at arabern. 

As the valorization of this CO₂ has proven to be a profitable business model, arabern has decided to expand the capture and liquefaction plant and thus further strengthen our partnership. Our joint pilot project will be transformed to a large-scale capture site "2.0". 

We chatted to Adrian Schuler to know more about the how and why.

7 questions to Adrian Schuler, managing director of ara region bern ag

Adrian, why did you decide to work with neustark?

Adrian Schuler: During various processes of wastewater treatment, recyclable and non-recyclable waste is produced in solid, liquid and gaseous form. One of these recyclable waste materials is CO₂, which is generated during the biogas upgrading process. This can now be put to effective use thanks to neustark's technology. Their business case is convincing, and the two strategies of our companies fit together perfectly: We recycle existing waste streams and turn them into a new, improved and environmentally friendly product.

Thanks to long-term contract with neustark, we have a good planning security. We follow the strategy of recovering all our emissions in a cost-covering manner. When investing, our main aim was to take on a pioneering role and be profitable early on. The voluntary carbon market (VCM) is still a nascent but growing rapidly. Over the next 10-15 years, this market will continue to evolve and the barriers to entry will likely increase.

And at the end of the day, the project benefits the environment. At arabern, we are not only concerned about clean water, but also about protecting waters in a sustainable manner and in harmony with nature and people. 

What happened to the excess CO₂ before the collaboration with neustark?

Adrian Schuler: For a long time, the CO₂ generated during the upgrading of biogas into biomethane was simply released back into the atmosphere through the chimney. Now it can be put to good use.

Here's how it works: Before the biogas can be fed into the regional energy supplier's natural gas grid as biomethane, it must be purified. A technical process is used to remove CO₂ from the biogas, which makes up around 35% of the raw gas. But what to do with all the CO₂ produced during this process? Exactly, this is where neustark comes into play!  

With neustark's solution, which is installed directly at the existing facility, we capture the CO₂ directly at its source. The CO₂ is already highly purified by the upstream processes, which means we can liquefy it directly on site to then transport it to our nearby sequestration sites. There, the CO₂ is durably removed from the atmosphere by storing it in demolition concrete. Like that, we create crucial negative emissions – and an additional source of income for our partners. Neustark purchases the CO₂ from biogas plants, which was previously simply released into the atmosphere unused, at a market price.   

Did you know that biogenic CO₂, which is produced in a wastewater treatment plant for example, is climate-neutral? When biomass is burned or fermented, CO₂ is released, which is part of the biogenic carbon cycle. This contrasts with the burning of fossil fuels, which releases CO₂ that has been trapped in the ground for millions of years. In other words, when biomass is burned, the CO₂ that was absorbed during the plants' growth cycle is simply released back into the atmosphere. The process is therefore CO₂-neutral. And by capturing and permanently storing the biogenic CO₂, we downright remove it from the atmosphere.

How did the contact with neustark come about in the first place?

Adrian Schuler: Valentin Gutknecht and Johannes Tiefenthaler (ed. the founders of neustark) approached arabern because they were looking for a stable source of biogenic CO₂ for their business model. Their solution convinced us, and for us, it's a win-win: our carbon dioxide is valorized and at the same time, we can further accelerate decarbonization. What’s more, this commitment is almost perfectly compatible with arabern's overarching goals: recycling of existing waste streams, instead of landfilling or releasing it into the environment, is what we follow, too. In addition, our plants naturally require energy to operate, and this should be compatible with our net zero targets.

Can you tell us to what extent the collaboration makes sense from a financial perspective?

Adrian Schuler: The construction of Kapok, our first pilot plant, was financed by neustark at the time. Up to now, we've received compensation for every ton of gaseous CO₂ that has been captured. Our surplus CO₂ has become a new source of income.

Ara region bern ag is now investing directly in the construction of the new site. From fall 2024, we will operate the new capture and liquefaction plants ourselves. We will then receive remuneration per ton of liquid CO₂ from neustark.

The decisive factor for this expansion was the fact that the existing plant cannot process the entire amount of CO₂ we generate each year. The new capture and liquefaction site should be able to process almost the entire amount, approx. 6,000 tons per year. It was clear to us that such an investment would have to be cost-covering. Financing through public wastewater fees is not doable, as there is no legal basis for it.

At arabern, we do not have the capability to cover the other end of the CO₂ storage process and thus generate so-called carbon removal certificates. Currently, at our location in Bern, the gaseous CO₂ is captured by neustark and locally liquefied to make it transportable. With the construction of the new plant, we will soon be operating the liquefaction process ourselves. Neustark, on their part, will coordinate the transport and permanent storage in collaboration with other partners. It's a double win: we are utilizing the waste from the sewage treatment plant in an ecologically effective way, and, we are valorizing our emissions volume by selling CO₂ to neustark. The business is not a goldmine, but it does contribute to the profitability of our company.

Do you see any other benefits from the partnership with neustark?

Adrian Schuler: Currently, the separation and liquefaction of CO₂ is the core of our collaboration. However, we can imagine replacing the nitrogen gas currently used for inerting the drying plant with liquid CO₂ in the future. This would make us not only a partner but also a customer of neustark. This would save on transport routes and close another material cycle.  

*Inerting is the process of adding an inert (non-combustible) gas or powder to a mixture to prevent an explosion from occurring.

Arabern will soon be capturing even more CO₂ thanks to the construction of the new plant. How did that come about?

Adrian Schuler: The neustark capture and liquefaction plant operated on our site is only able to process part of our surplus CO₂. Building and operating our own plant is an efficient division of tasks. The employees at arabern are familiar with technical systems and monitor the processes around the clock. With their expertise, they ensure the smooth operation and maintenance of the CO₂ capture and liquefaction facility. The plant is also monitored technically by our existing process control system. Neustark can therefore concentrate on the transportation and permanent storage of the CO₂.

Interesting fact: Did you know that arabern's plants are in operation 365 days a year, 24 hours a day? This is necessary to ensure the highest quality of environmental services.

Adrian, one last one: Can you give us some insights into how your professional environment reacted to working with neustark?

Adrian Schuler: To be honest, our employees were rather skeptical at the beginning. Our core business is and remains wastewater treatment. Integrating additional processes smoothly into an existing plant is not easy. However, ara region bern ag is no longer "just" responsible for clean water. Generating energy, closing cycles and recycling wastewater have been part of our business model for many years. Education and time is needed to introduce new technology and processes, such as the one provided by neustark. The expansion of our collaboration is proof that this has worked very well and promises much potential in the future.

We have also received a lot of very good external feedback – even from our colleagues at other wastewater treatment plants. We're an open book in our industry and always try to be open to innovation and try new things. With this successful collaboration to valorize CO₂ and become even more ecological, we strive to open opportunities for the entire industry.

Since the start of our collaboration in July 2021, we have successfully captured and liquefied almost 1,000 tons of CO₂ at arabern. The construction of the new site is another milestone in our partnership and a strong signal towards the decarbonization of our planet. We are proud to be working towards a sustainable future together with partners like arabern and look forward to capturing and permanently removing thousands of more tons of CO₂, together!