New technology to obtain oxygen, fuel from the salt water of Mars

Electrolysis, a process that uses electricity to split water into hydrogen and oxygen, requires the removal of the salt. It is a cumbersome and costly undertaking in a harsh and dangerous environment.

If oxygen and hydrogen could be extracted directly from brackish water, this electrolysis process would be much less complicated and less expensive.

A new technology developed by engineers at Washington University’s McKelvey School of Engineering in St. Louis does the same. While useful on Earth, where it opens up the oceans as a viable source of oxygen and fuel, this new technology, i.e. the brine electrolyser, can obtain oxygen, fuel even from the salt water of Mars.

Vijay Ramani from the Enter for Solar Energy and Energy Storage, Washington University in St. Louis said: “Our Martian brine electrolyser radically changes the logistical calculation of missions to Mars and beyond.”

The system can produce 25 times more oxygen than MOXIE using the same amount of energy. It also has hydrogen, which could be used to power the astronauts’ journey home.

This brine electrolyzer contains a lead rutenate pyrochlore anode developed in combination with platinum on carbon cathode. The careful design and unique anode allow the system to operate without heating or purifying the water source.

Ramani said, “These carefully designed components, coupled with the optimal use of traditional electrochemical engineering principles, have produced this high performance.”

Shrihari Sankarasubramanian, a research scientist from Ramani’s group and first joint author of the paper, said: “Paradoxically, the perchlorate dissolved in water, the so-called impurities, actually helps in an environment like that of Mars.”

“They prevent the water from freezing and also improve the performance of the electrolyser system by lowering the electrical resistance.”

Pralay Gayen, an associate postdoctoral researcher in Ramani’s group and also a joint first author of this study, said: “Having demonstrated these electrolysers in demanding Martian conditions, we also intend to deploy them in much milder conditions on Earth to use brackish or salt water to produce hydrogen and oxygen, for example through seawater electrolysis.”

Journal reference:

1. Pralay Gayen et al., “Collection of fuel and oxygen from the Martian regolith brine”, PNAS (2020). DOI: 10.1073 / pnas.2008613117