They are small, inconspicuous and green – and hold great potential. Microalgae are among the most fascinating organisms on our planet. As part of their Bachelor’s thesis, Zoe Abeln and Peter Zeller, students on the Energy and Environmental Engineering degree programme, investigated how a microalgae reactor could be scaled up to cover an area equivalent to half a football field: such a facility could soon form the basis for a Swiss microalgae production operation.
Aquariums for urban life
The two students had already worked with microalgae earlier in their studies – microscopic single-celled organisms that absorb CO₂, produce oxygen and can be used as food or biofuel. At that time, the students had seen pictures of algae reactors in cities and at bus stops – essentially aquariums, but for algae. “My immediate thought was that this could be an efficient way of cleaning urban air,” says Abeln. Together, the students contacted Arrhenius AG, a spin-off of the Lucerne University of Applied Sciences and Arts that develops large-scale algae reactors. They had already worked with the company on an earlier project. Their aim was now to investigate whether Arrhenius’s reactor design could be used for large-scale food production. “From then on, the Bachelor’s thesis practically wrote itself,” recalls Zeller. They compared technologies, analysed costs and efficiencies, tested reactor geometries and simulated the process using Excel. Arrhenius provided extensive support in this regard, offering technical expertise, contacts and practice-oriented insights. The pair were looking into microalgae – tiny single-celled organisms that absorb CO₂, produce oxygen and can be used as food or biofuel. At the time, the students had seen pictures of algae reactors in towns and cities or at bus stops – like aquariums, but for algae. “I thought straight away that this would be an efficient way to clean the city air,” says Abeln. Together, they got in touch with Arrhenius AG, a spin-off from Lucerne University of Applied Sciences and Arts that develops large-scale algae reactors. They had already worked with the company on a project. Their aim now was to investigate whether Arrhenius’s reactor design was suitable for large-scale food production. “From then on, the Bachelor’s thesis practically wrote itself,” recalls Zeller. They compared technologies, analysed costs and efficiency levels, tested reactor geometries and simulated the process using Excel. Arrhenius provided them with extensive support in the form of technical expertise, contacts and practical advice.
Zoe Abeln and Peter Zeller
Project leaders
“With larger facilities, microalgae could become an alternative to meat or fish.”
A full house at the final presentation
For their project, Abeln and Zeller obtained quotations, technical specifications and pricing information from numerous companies. Some companies responded openly, while others were unsure what to make of an enquiry from two students. “Some companies took us seriously, others less so,” says Zeller. Microalgae are now regarded as a promising solution to major challenges relating to nutrition and climate protection. This was also evident during the presentation of their work, which attracted many lecturers from other disciplines. Although the students’ interest in the topic remains strong, they are not planning to continue immediately: “The motivation is there, but there are no immediate plans to continue working on it right away,” says Abeln. Zeller would like to explore other topics before potentially returning to algae at a later date.
Interview with the project leaders
Why microalgae of all things?
Peter Zeller: It sounded a bit unusual at first, but the more we looked into it, the more fascinating it became.
Zoe Abeln: We wanted to work on something meaningful. Microalgae grow quickly, require very little space and help combat climate change: they can absorb up to 50 times more CO₂ from the air than trees. We found that incredibly impressive.
How exactly does this work?
Zoe Abeln: Microalgae absorb CO₂ and convert it into biomass through photosynthesis. If that biomass is then stored in the ground, the CO₂ does not return to the atmosphere. In this way, microalgae actively remove greenhouse gases from the air. This is a different approach to that taken by many climate protection measures, which primarily focus on reducing emissions.
Peter Zeller: And such facilities can be set up almost anywhere – on brownfield sites, industrial land or even in deserts.
But your facility is primarily geared towards food production, right?
Peter Zeller: Yes, in Switzerland it makes particular sense to use microalgae as a high-quality food product. A good example is spirulina, a genuine superfood packed with protein, iron and gamma-linolenic acid (GLA).
Zoe Abeln: Of course, production is still relatively expensive at the moment. With larger facilities, however, microalgae could become a real, sustainable alternative to meat or fish.
Had you worked with microalgae before?
Zoe Abeln: Only with macroalgae – such as nori in sushi (laughs). I had also bought spirulina powder to put in my smoothies. The taste is unusual at first, but it’s just a matter of getting used to it.
Peter Zeller: For me, it came up during my studies in the context of synthetic fuels: microalgae were presented as a climate-friendly alternative to petrol or diesel.
Alissa Tophinke
Biotechnologist, Arrhenius AG
“Zoe and Peter approached the project with tremendous commitment. Their enthusiasm for microalgae was palpable, and their learning curve was impressive. Through their creative ideas and critical thinking, they have added real value to our start-up: their work makes an important contribution to the development of practical solutions.”
How did you approach the development process?
Peter Zeller: We broke the entire process down into individual sub-functions and worked with Arrhenius AG to find the best solution for each one. This method is known as a morphological box, a useful tool for approaching complex problems in a structured way.
Zoe Abeln: Specifically, we examined questions such as: how can light be distributed most effectively? Which materials offer the greatest durability? And how is it possible to save energy and reduce costs? We didn’t just look at the technical aspects, but also at maintenance requirements and suitability for everyday use.
How realistic is it that the idea will be implemented?
Peter Zeller: Arrhenius AG is already continuing the development of some of the concepts. A small prototype is expected to be built in Lucerne soon. So the project is not remaining purely theoretical, although some fine-tuning is still required.
Zoe Abeln: For us, it was certainly an important step towards advancing the technology so that it can one day make a real contribution to climate protection.
What excited you most about the project?
Zoe Abeln: The level of interest the topic generated! Whether from companies or our fellow students, many people found the idea exciting and wanted to learn more.
Peter Zeller: In some Zoom meetings, there were even three representatives from a single company because they recognised the potential. We realised that many people took both us and our work seriously.
That was incredibly motivating. What will you personally take away from the experience?
Peter Zeller: Technology is never just about technology. We need to think in a networked and creative way if we are to make progress.
Zoe Abeln: What is more, microalgae may be tiny, but their potential is truly enormous.
