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From research challenge to standard product
From research challenge to standard product
From left: Keith Alan McCall, Eystein Opsahl amd Elin Austerheim. Photo: Andreas R. Graven, NORCE
News（https://www.norceresearch.no/en/News?categories=24012016）
Published: 20.10.2026
Oppdatert: 26.10.2026
Katrine Jaklin（https://www.norceresearch.no/en/persons/katrine-jaklin/24149247）
When Eystein Opsahl and his colleagues in the Industrial Biotechnology research group needed to measure hydrogen levels in a pilot reactor for gas fermentation, there were no sensors available that could withstand the process conditions. So they developed a new solution.
What started as a practical challenge in an ongoing research project gradually developed into a collaboration with the Danish company Unisense and a technical solution that has now become part of the company’s standard product range.
A bottleneck in the research
Gas fermentation is a technology in which microorganisms use gases such as hydrogen, CO₂ or methane as feedstock and convert them into valuable products such as chemicals, fuels or other bio-based compounds. To understand and optimise some of the most promising processes, it is important to be able to measure hydrogen levels directly in the bacterial culture inside the bioreactor.
The challenge was that the reactors are sterilised at 121 °C before use, while available sensors for measuring dissolved hydrogen had limited temperature tolerance and measuring range. They were also not designed to be attached to a bioreactor and used over long periods of time, especially not in potentially explosive atmospheres (ATEX), which any industrial-scale use of hydrogen gas entails. As a result, the researchers lacked a robust solution for continuous measurement under realistic process conditions. Eystein Opsahl explains why such measurements are crucial:
– By following how the hydrogen concentration changes under different operating conditions, we can better understand what the bacteria need in order to increase the reaction rate and use nutrients more efficiently. The sensor has, among other things, been used at pilot scale to produce acetic acid from hydrogen and carbon dioxide. This opens up opportunities for a more circular bioeconomy, where off-gases from other industries can be used to create something valuable. When hydrogen is one of the reactants, it is essential to know how much is available so that we avoid wasting hydrogen or causing the reaction to stop, says Opsahl.
Eystein Opsahl in the control room during a test.
A solution developed through collaboration
To solve the problem, the research group contacted Unisense. Together they developed a solution based on a retractable sensor housing, allowing the sensor to be withdrawn from the reactor during sterilisation and reinserted when the process starts, thereby avoiding the temperature issue altogether. At the same time, the sensor can be sterilised using chemical methods, reinserted once the reactor is ready, and kept separate from the surrounding atmosphere using inert gas. The hydrogen sensor is made of stainless steel, as is normally required in bioprocesses, and withstands the demanding process conditions the researchers were working with. None of this is technologically revolutionary in itself, but the application is all the more important: NORCE is the first to demonstrate that this can be done. Opsahl emphasises that the solution builds on both long-term investments and broad collaboration:
– We are standing on the shoulders of many people here. Projects such as PYROCO2, with major investments in research infrastructure, are only made possible through the efforts of technicians, engineers, researchers, support functions and public funding sources. Through SFI Industrial Biotechnology, we had both the equipment and the opportunity to finance the development work.