Publication

Modelling Gas Bubble Dynamics and Electrochemical Reaction Overpotentials in Reduced Gravitational Conditions

2025

Abstract

The Oxygen Generator Assembly (OGA) aboard the International Space Station (ISS) consumes a substantial portion of the overall Environmental Control and Life Support System (ECLSS) power budget (32.6% 1 ). It has been deemed both unreliable and cumbersom 2 . In preparation for long-duration deep-space missions, where resupply is impossible, reliable and energy-efficient systems are needed to produce oxygen for life support and hydrogen for rocket fuel 1 . However, under microgravity conditions, traditional density-driven mechanisms such as buoyancy-driven bubble detachment become ineffective 3 . Consequently, gas bubble froth accumulates on electrode surfaces, significantly elevating electrochemical overpotentials and obstructing ionic transport, thereby diminishing electrolysis efficiency significantly. Recent terrestrial simulations have examined bubble-induced effects on overpotentials 4 , yet there is not a comprehensive framework for electrolysis in microgravity. Here, we propose the first integrated theoretical model that explicitly incorporates reduced gravitational effects and microgravity-specific interfacial phenomena into time-resolved simulations. Using Bremen drop-tower experiments at different hydrogen generation rates for validation, we demonstrate how interlinked electrochemical and fluid dynamics can be accurately captured under microgravity conditions and illustrate these phenomena' critical impact on hydrogen generation rates. These findings provide foundational insight into the high-performance, robust electrolyser systems designed for extended deep-space missions. 1 Ross, B., Haussener, S. & Brinkert, K. Assessment of the technological viability of photoelectrochemical devices for oxygen and fuel production on Moon and Mars. Nature Communications 14 , 3141 (2023). 2 Jones, H. W. in International Conference on Environmental Systems (ICES 2016). 3 Brinkert, K. et al. Efficient solar hydrogen generation in microgravity environment. Nature Communications 9 , 2527 (2018). 4 Ross, B., Haussener, S. & Brinkert, K. Impact of Gas Bubble Evolution Dynamics on Electrochemical Reaction Overpotentials in Water Electrolyser Systems. The Journal of Physical Chemistry C 129 , 4383-4397 (2025).

Official source

https://infoscience.epfl.ch/entities/publication/c6ab259c-87ea-4897-93cc-4959ac4cee06

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2025

Abstract

Official source

https://infoscience.epfl.ch/entities/publication/c6ab259c-87ea-4897-93cc-4959ac4cee06

Related concepts (32)

Hydrogen production

Hydrogen production is the family of industrial methods for generating hydrogen gas. As of 2020, the majority of hydrogen (~95%) is produced from fossil fuels by steam reforming of natural gas and other light hydrocarbons, partial oxidation of heavier hydrocarbons, and coal gasification. Other methods of hydrogen production include biomass gasification, methane pyrolysis, and electrolysis of water. Methane pyrolysis and water electrolysis can use any source of electricity including solar power.

Electrolysis of water

Electrolysis of water is using electricity to split water into oxygen (O2) and hydrogen (H2) gas by electrolysis. Hydrogen gas released in this way can be used as hydrogen fuel, but must be kept apart from the oxygen as the mixture would be extremely explosive. Separately pressurised into convenient 'tanks' or 'gas bottles', hydrogen can be used for oxyhydrogen welding and other applications, as the hydrogen / oxygen flame can reach circa 2,800°C. Water electrolysis requires a minimum potential difference of 1.

Hydrogen economy

The hydrogen economy uses hydrogen to decarbonize economic sectors which are hard to electrify, essentially, the "hard-to-abate" sectors such as cement, steel, long-haul transport, etc. In order to phase out fossil fuels and limit climate change, hydrogen can be created from water using renewable sources such as wind and solar, and its combustion only releases water vapor into the atmosphere. Although with a very low volumetric energy density hydrogen is an energetic fuel, frequently used as rocket fuel, but numerous technical challenges prevent the creation of a large-scale hydrogen economy.

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