Electrolysis has been a mainstay of crewed mission designs for the outer solar system for decades.
It is the most commonly used methodology to split oxygen from water, creating a necessary gas from a necessary liquid.
However, electrolysis systems are bulky and power-intensive, so NASA has decided to look into alternative solutions.
They supported a company called Precision Combustion, Inc (PCI) via their Institutes for Advanced Concepts (NIAC) grant to work on a system of thermo-photo-catalytic conversion that could dramatically outperform existing electrolysis reactors.
PCI’s thermo-photo-catalytic reactor is one iteration of its trademarked “Microlith” catalytic reactor.
A Microlith looks like a filtered screen, but the screen can be coated in various materials. In this case, that coating is likely something like titanium dioxide, which acts as a photocatalyst. However, the company keeps the exact formulation of the coating close to the vest.
In thermo-photo-catalysis, a chemical process combines heat (“thermal”) with light (“photo”) to catalyze a chemical reaction.
Microlith screens are designed to be heated by passing a current through the metal substrate and the photocatalytic coating, like titanium dioxide.
Any titanium dioxide the Microlith uses is likely doped, as typically, it only reacts to ultraviolet light and must be doped to be able to absorb regular visible light.
When water passes through the microsized channels intentionally created inside the MIcrolith screen, it is exposed to titanium dioxide holes and electrons created by the light’s absorption.
The water then undergoes a redox reaction, similar to what happens in a conventional electrolysis chamber.
However, the Microlith system has several significant advantages over electrolysis. For one, it’s much smaller, which significantly decreases its size and weight—always an important consideration in spaceflight.
Second, it requires less energy, as there is a relatively minor pressure drop and good thermal transfer to ensure the catalyst is operating at full capacity. It also has a high throughput rate, making it more efficient than other thermophotocatalytic converters.
PCI itself is no stranger to government grants, either. It was founded in 1987 by engineer and inventor William Pfefferle and has been receiving grants from NASA since at least 2011.
The company specializes in fuel cell systems and other technologies related to energy production. It’s received half a dozen federal grants in the last few years to work on application-specific use cases of its various technologies.
Those applications are broad – the Microlith system can be used in various other applications, depending on its coating. Splitting water would also create hydrogen, which has been touted as a “fuel of the future” for some time.
However, it’s never been possible to generate it economically from water, though a scaled-up Microlith system might be a step in that direction. Other use cases include converting CO2 into valuable materials and even acting as a filter in some cases.
However, for any of those end-use cases to be realized, the company needs to do more R&D, which is precisely what the NIAC grant is for. In its press release, the company mentions a 2039 Mars mission as a potential use case for its thermophotocatalytic system to split water molecules. That’s still far off, but it will give the company time to work towards its final design.
Written by Andy Tomaswick/Universe Today.
