Daniela Zertuche Moreno, Aradhana Singh, Dibyojyoty Nath, Ioannis A. Ieropoulos
Our Mi-Hy project partners at the University of Southampton have recently published a review article about how microbial fuel cells (MFCs) can be used to recycle human waste to enhance self-sustainability of spacecraft and missions. With this article, they’re addressing an important topic that hasn’t been properly addressed yet: creating true closed-loop systems for long-duration space exploration.
The key shift here is moving away from the perspective of simply removing waste, and instead focusing on recovering the resources we actually need from it. This becomes especially important for space missions that will produce significant amounts of urine that can be utilised by MFCs.
Recent advances in MFCs have shown promising results, with power generation of 1-2 mW per single MFC per ml of urine. Central to our EU-funded Mi-Hy project is an integrated MFC-hydroponic system where MFCs not only produce electricity but also recover valuable nutrients from waste to support food production. The process works like this: astronauts produce waste, which MFCs convert into electricity and safe liquid fertilizer. The electricity powers LED grow lights, and the fertilizer nourishes hydroponic vegetable gardens. Astronauts then harvest fresh vegetables, completing the sustainable cycle (see graphical abstract, Figure 1).
The power of technologies such as Mi-Hy is that it allows vegetables to be produced in a self-sustainable manner. The excess carbon and inorganic nutrients (nitrogen, phosphorus, potassium) in urine and sewage get turned into plant biomass and electricity, so that astronauts could grow their own food while generating power from their own waste.
Moreno, D. Z., Singh, A., Nath, D., & Ieropoulos, I. A. (2025). Microbial fuel cell centric nutrient rebalancing and recycling from human waste in space missions. Emerging Topics in Life Sciences, ETLS20240003, https://doi.org/10.1042/ETLS20240003.
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