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The active Martian water cycle, that is, the presence of shallow water and soluble perchlorate salts in Martian soil, enables the production of life-supporting hydrogen and oxygen fuel on Mars by electrolysis of perchlorate brines. A team of scientists at Washington University in St. Louis has demonstrated an approach to produce ultra-pure hydrogen and oxygen from liquid Martian brines at minus 36 degrees Celsius (minus 32.8 degrees Fahrenheit).
This illustration shows Jezero Crater, the landing site of NASA’s Perseverance Mars 2020 rover, as it may have been billions of years ago on Mars when it was a lake. Image credit: NASA / JPL-Caltech.
“Our Martian brine electrolyzer radically changes the logistical calculus of missions to Mars and beyond,” said Professor Vijay Ramani, a researcher at the Center for Solar Energy and Energy Storage at Washington University in St. Louis.
“This technology is equally useful on Earth, where it opens up the oceans as a viable source of oxygen and fuel.”
NASA’s Perseverance rover is on its way to Mars now, with instruments that will use high-temperature electrolysis.
However, the Mars Oxygen In Situ Resource Utilization Experiment (MOXIE) will produce only oxygen from carbon dioxide in the air.
The electrolyzer developed by Professor Ramani and his colleagues can produce 25 times more oxygen than MOXIE using the same amount of energy. It also produces hydrogen, which could be used as fuel for the astronauts’ journey home.
“Our novel brine electrolyzer incorporates a lead ruthenate pyrochlorine anode developed by our team in conjunction with platinum on carbon cathode,” said Professor Ramani.
“These carefully engineered components, along with optimal use of traditional electrochemical engineering principles, have produced this high performance.”
The careful design and unique anode allow the equipment’s electrolyzer to function without the need to heat or purify the water source.
“Paradoxically, perchlorate dissolved in water, so-called impurities, actually help in an environment like Mars,” said Dr. Shrihari Sankarasubramanian, a researcher at the Center for Solar Energy and Energy Storage and the Department of Energy, Environment Environment. and Chemical Engineering at Washington University in St. Louis.
“They prevent the water from freezing and also improve the performance of the electrolyzer system by reducing electrical resistance.”
Typically, water electrolyzers use highly purified deionized water, which increases the cost of the system.
A system that can run on salt or suboptimal water, as the technology demonstrated by the team, can significantly improve the economic value proposition of water electrolyzers everywhere, even here on Earth.
“Having demonstrated these electrolyzers in the demanding Martian conditions, we intend to implement them also in much milder conditions on Earth to use food from brackish or salty water to produce hydrogen and oxygen, for example through the electrolysis of water from sea, ”said Dr. Pralay Gayen, a postdoctoral researcher in the Department of Energy, Environmental Engineering and Chemistry at Washington University in St. Louis.
The team’s work was published in the procedures of the National Academy of Sciences.
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Pralay gayen et al. Harvesting fuel and oxygen from Martian regolithic brine. PNAS, published online November 30, 2020; doi: 10.1073 / pnas.2008613117
This article is based on a press release provided by Washington University in St. Louis.
