Predicting the efficiency of oxygen-evolving electrolysis on the Moon
and Mars

Date:
February 8, 2022
Source:
University of Manchester
Summary:
Scientists have today provided more insight into the possibility of
establishing a pathway to generate oxygen for humans to potentially
call the Moon or Mars 'home' for extended periods of time.



FULL STORY ========================================================================== Scientists at The University of Manchester and The University of Glasgow
have today provided more insight into the possibility of establishing
a pathway to generate oxygen for humans to potentially call the Moon or
Mars 'home' for extended periods of time.


========================================================================== Creating a reliable source of oxygen could help humanity establish
liveable habitats off-Earth in an era where space travel is more
achievable than ever before. Electrolysis is a popular potential method
which involves passing electricity through a chemical system to drive
a reaction and can be used to extract oxygen out of lunar rocks or to
split water into hydrogen and oxygen.

This can be useful for both life support systems as well as for the
in-situ production of rocket propellant.

Until now however, how lower gravitational fields on the Moon (1/6th
of Earth's gravity) and Mars (1/3rd of Earth's gravity) might affect gas-evolving electrolysis when compared to known conditions here on
Earth had not been investigated in detail. Lower gravity can have a
significant impact on electrolysis efficiency, as bubbles can remain
stuck to electrode surfaces and create a resistive layer.

New research published today in Nature Communications demonstrates how a
team of researchers from The University of Manchester and the University
of Glasgow undertook experiments to determine how the potentially
life-giving electrolysis method acted in reduced gravity conditions.

Lead engineer of the project, Gunter Just, said: "We designed and built
a small centrifuge that could generate a range of gravity levels relevant
to the Moon and Mars, and operated it during microgravity on a parabolic flight, to remove the influence of Earth's gravity.

"When doing an experiment in the lab, you cannot escape the gravity
of Earth; in the almost zero-g background in the aircraft, however, our electrolysis cells were only influenced by the centrifugal force and so we could tune the gravity-level of each experiment by changing the rotation
speed. The centrifuge had four 25 cm arms that each held an electrolysis
cell equipped with a variety of sensors, so during each parabola of around
18 seconds we did four simultaneous experiments on the spinning system.

"We also operated the same experiments on the centrifuge between 1 and
8 g in the laboratory. In this configuration we had the arms swinging
so that the downwards gravity was accounted for.It was found that
the trend observed below 1 g was consistent with the trend above 1 g,
which experimentally verified that high gravity platforms can be used to predict electrolysis behaviour in lunar gravity, removing the limitations
of needing costly and complex microgravity conditions. In our system,
we found that 11% less oxygen was produced in lunar gravity, if the
same operating parameters were used as on Earth." The additional power requirement was more modest at around 1 %. These specific values are
only relevant to the small test cell but demonstrate that the reduced efficiency in low gravity environments must be taken into account when
planning power budgets or product output for a system operating on
the Moon or Mars. If the impact on power or product output was deemed
too large for a system to function properly, some adaptations could be
made that may reduce the effect of gravity, such as using a specially structured electrode surface or introducing flow or stirring.

========================================================================== Story Source: Materials provided by University_of_Manchester. Note:
Content may be edited for style and length.


========================================================================== Journal Reference:
1. Bethany A. Lomax, Gunter H. Just, Patrick J. McHugh, Paul
K. Broadley,
Gregory C. Hutchings, Paul A. Burke, Matthew J. Roy,
Katharine L. Smith, Mark D. Symes. Predicting the efficiency
of oxygen-evolving electrolysis on the Moon and Mars. Nature
Communications, 2022; 13 (1) DOI: 10.1038/ s41467-022-28147-5 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2022/02/220208113903.htm
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