More Efficient Oxygen Production in Space Thanks to Magnetism

How can hydrogen be produced efficiently and reliably in space? In a study published in Nature Chemistry, an international research team involving researchers from ZARM presents a solution.

Since the beginning of human spaceflight in the 1960s, there has been a challenge for which there is still no simple solution: the reliable and efficient production of oxygen in space. On the International Space Station (ISS), this task is currently performed by heavy, maintenance-intensive, and energy-intensive systems—not an ideal solution for long-term missions to the Moon or Mars. In a study published in Nature Chemistry, an international research team from the Center of Applied Space Technology and Microgravity (ZARM) at the University of Bremen, the University of Warwick, and the Georgia Institute of Technology presents a remarkably simple and elegant alternative. The use of magnetism is expected to make future oxygen production easier and more sustainable.

The common way to produce oxygen in space is by water electrolysis, a process that splits water into hydrogen and oxygen using electrodes immersed in an electrolyte. In the weightlessness of orbit, however, gas bubbles do not float upwards. Instead, they tend to stick to the electrodes and remain suspended in the liquid, making the process much more difficult and energetically costly than on Earth. In order to separate the gas bubbles from the liquid and extract the oxygen, a variety of methods can be used. Current life support systems on board the International Space Station spin water in a centrifuge to separate oxygen and hydrogen gas bubbles from the liquid. Although effective, this method is heavy, power-hungry, and mechanically complex – making it less than ideal for crewed deep space missions, where every kilogram of equipment is critical during launch and every watt of power matters once in space.

The Solution: Magnetism

The research team was able to demonstrate that magnetic fields can support the separation of gas bubbles from electrodes in microgravity. Using off-the-shelf permanent magnets, the team developed a passive phase separation system that pushes the bubbles away from the electrodes and collects them at designated spots. To achieve this breakthrough, the team developed two complementary approaches. The first takes advantage of how water naturally responds to magnets in microgravity, guiding gas bubbles toward collection points.

The second method uses magnetohydrodynamic forces, which arise from the interaction between magnetic fields and electric currents generated by electrolysis. This creates a spinning motion in the liquid that separates gas bubbles from water through convective effects – achieving phase separation similar to mechanical centrifuges used on the ISS, but using magnetic forces instead of mechanical rotation.

The findings published today are the result of four years of joint research. ?lvaro Romero-Calvo from Georgia Tech came up with the original idea and performed the calculations and numerical simulations as early as 2022. He then continued to develop a system for splitting water into oxygen and hydrogen using magnetic effects. To prove and quantify the theory in electrochemical and photoelectrochemical setups, Katharina Brinkert’s (University of Warwick until 2024, now ZARM) team developed experiments and devices to be tested in microgravity. “We were able to prove that we do not need centrifuges or any mechanical moving parts for separating the produced hydrogen and oxygen from the liquid electrolyte. We do not even need additional power. Instead, it’s a completely passive, low-maintenance system” explains Katharina Brinkert. ?mer Akay was responsible for carrying out the experiments in the microgravity lab of ZARM, the Bremen Drop Tower in Germany, and for compiling all information gathered for the publication: “Our developed cells allow the production of hydrogen and oxygen from water electrolysis in microgravity at nearly terrestrial efficiencies.”

Successful Tests in Microgravity

The experiments confirmed that magnetic forces can improve gas bubble detachment and movement and enhance the efficiency of the electrochemical cells by up to 240 percent. This breakthrough solves a long-standing spaceflight engineering problem and opens the door to developing simpler, more robust, and more sustainable life support systems for human space exploration. The next step for the team is to further validate the system through suborbital rocket flights.

The project is funded by the German Aerospace Center (DLR), the European Space Agency (ESA), and the National Aeronautics and Space Administration (NASA).