Since sending the first human into space in the 1960s, the solution to one key challenge has remained elusive: the efficient and reliable production of oxygen in space. On the International Space Station this problem is addressed by heavy and energy-intensive systems that are not ideal for long-duration space missions.
In today's Nature Chemistry publication, a team of researchers from the University of Warwick, the Center of Applied Space Technology and Microgravity (ZARM) at the University of Bremen, and the Georgia Institute of Technology, describe a remarkably simple and elegant solution to make future oxygen production lighter, simpler and more sustainable -using magnetism.
Professor Katerina Brinkert, Honorary Professor, University of Warwick & Professor of Human Space Exploration Technologies & Director of ZARM said: "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 is a completely passive, low-maintenance system."
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, requiring a complex, bulky and power-hungry fluid management system that is impractical for long-duration missions because in space, every kilogram of equipment and every watt of power matters.
The international team of scientists from the University of Warwick, Georgia Institute of Technology and ZARM were able to demonstrate that a simple magnetic fields solution can support the separation of gas bubbles from electrodes in a microgravity environment, created at the Bremen Drop Tower, without bulky equipment.
Dr. Álvaro Romero-Calvo, Assistant Professor, Georgia Institute of Technology said: "Our team was able to prove that magnetic forces can feasibly control electrochemical bubbly flows in microgravity, departing from the state-of-the-art in low-gravity fluid mechanics and enabling future human spaceflight architectures."
Using off-the-shelf permanent magnets, the research 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 to allow the collection of oxygen bubbles from the electrode. 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 like 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. Álvaro Romero-Calvo from Georgia Tech produced 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 electro- and photoelectrochemical setups, Katharina Brinkert's team at Warwick (until 2024) and then ZARM, developed experiments and devices to be evaluated in microgravity.
Dr. Shaumica Saravanabavan, PhD researcher, University of Warwick said: "During my trips to ZARM, we confirmed the magnetic buoyancy effect for phase separation in (photo-)electrolysis cells in multiple Drop Tower experiments, using electrode materials we in part fabricated at Warwick. I'm proud to have contributed to advancing sustainable energy technologies beyond Earth applications."
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.
Ömer Akay, Research Associate at ZARM, University of Bremen said: "Our developed cells allow the production of hydrogen and oxygen from water electrolysis in microgravity at nearly terrestrial efficiencies."
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.
