Green City Solutions congratulates Leon Alpen
We are delighted at Green City Solutions to celebrate our team member Leon Alpen, who has been awarded the Possehl-Ingenieurpreis 2025 by Technische Hochschule Lübeck. Under the heading “Rethinking sustainable air filtration”, he received first prize for his thesis “Design, Construction and Evaluation of a Scale-Down BioTech Air Filter – MicroBreeze” as part of his Bachelor’s degree in Environmental Engineering and Management – supervised by Prof. Dr.-Ing. Claas Heymann at TH Lübeck and carried out in close collaboration with Green City Solutions.
Photo: Agentur 54°/Felix König, Technische Hochschule Lübeck on LinkedIn
From CityTree and CityBreeze to MicroBreeze: regenerative bio-air filters in a new format
We develop innovative solutions that use living moss to naturally filter and cool the surrounding air, creating a pleasant and healthier microclimate.
Leon Alpen’s MicroBreeze prototype directly builds on this vision and “is based on the same philosophy”: He designed, engineered, 3D-printed and experimentally evaluated a compact BioTech air filter for indoor environments – for example in offices or private living spaces. As with our CityTree, specially selected moss species act as natural high‑performance filters that capture fine dust, cool the air and help improve air quality – “a previously unique concept”, as TH Lübeck describes it.
“Building bridges between theory and practice”
The Possehl Engineering Award honours projects that “build bridges between ideas and implementation” and “between theory and application“, as Prof. Dr. Wolfgang Sandberger, Chair of the Possehl Foundation, emphasised when paying tribute to the nominated students and award recipients.
In total, nine graduates presented their theses to the public on 9 December at the Bauforum of TH Lübeck. In addition to Leon, Nina Gierke and Wilhelm Frommholz were also “recognised for their outstanding achievements”.
Photo: Agentur 54°/Felix König, Technische Hochschule Lübeck on LinkedIn
“Smart, robust, future-proof”: interdisciplinary engineering at its best
The jury was particularly impressed by the interdisciplinary depth of Leon Alpen’s work: “biology, process engineering, mechatronics, air pollution control, industrial engineering and manufacturing technology” fließen in den MicroBreeze-Prototyp ein. „All of these fields are part of the Environmental Engineering and Management curriculum and provided the basis for his successful Bachelor’s thesis“.
This is what practice-oriented environmental engineering can look like: from the initial concept and technical design through 3D printing to the experimental evaluation of filter performance. As such, MicroBreeze embodies exactly what Green City Solutions stands for: data-driven, plant-based innovation that measurably reduces local air pollution.
In the context of the award, Leon Alpen expressed his “hope that his prototype will be implemented in practice in the future“. At the same time, he voiced concern that societal attention has shifted away from climate protection and stressed his hope “that more public investment will be made”, as reported by idw.
Photo: Agentur 54°/Felix König, Technische Hochschule Lübeck on LinkedIn
Congratulations – and thank you, Leon!
Dr. Muriel Helbig, President of Technische Hochschule Lübeck, Lübeck, summed up the evening by saying that the Possehl Engineering Award ceremony is “an incredibly exciting and wonderful moment for all of us” and that the record number of nominations shows “how committed our graduates are.” THL added on LinkedIn: „Congratulations! We are very proud of you and grateful for the dedication of our lecturers, which makes such work possible.”
We would like to echo this gratitude and these congratulations and say:
Congratulations, dear Leon, on the well-deserved Possehl Engineering Award 2025!
With “MicroBreeze”, you have convincingly demonstrated how our moss filters – the world’s first regenerative bio‑air filters – can be translated into new applications. We are proud to have you on the team and look forward to continuing our work together on cleaner, cooler and healthier air for urban spaces – and indoor environments.
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