Researchers from the Norwegian Institute of Bioeconomy Research (NIBIO) and the Norwegian University of Life Sciences have collaborated to develop a new method for producing green biomethane, a sustainable alternative to natural gas.

Their collaboration is documented in five scientific papers. The papers were produced in 2024 and 2025 and describe how biofilm-based processes can be used to convert carbon dioxide and syngas into biomethane with over 96 percent purity. The method could support the development of circular carbon systems.

In an article on the NIBIO website, Dr Lu Feng explains that unlike in traditional biogas production where organic waste is decomposed, the biofilm method captures and processes gas streams using self-selected microorganisms harboured within thin biofilm under oxygen free conditions. Among other things, the researchers experimented with adding selected microorganisms – a process known as bioaugmentation – to improve methane production. By introducing specific methane-producing microbes into fixed or moving bed reactors, the research team was able to steer the process towards more efficient CO₂ conversion.

According to Dr Lu Feng, the biofilms the team has developed provide a stable and efficient process which helps retain the microbes, improve gas–liquid contact, and largely increase contact surface for the reaction. They also tolerate harmful substances that would otherwise disrupt gas production.

He says biofilms can help manage challenges such as high levels of ammonia and hydrogen sulphide (H2S). These are substances often found in industrial gas streams and can be problematic in conventional bioreactors.

In one study, the team tested how biofilm reactors handle H2S. The results showed that systems without biofilm lost up to 30 percent of the methane, while the biofilm reactors maintained high methane quality even at extremely high H2S content.

The researchers also examined the effect of ammonia, which usually inhibits methane production. In this study, they used an Anaerobic Moving Bed Biofilm Reactor and found that the biofilms were able to produce methane even at high ammonia concentrations.

In another study, the researchers tested the biofilm method on syngas – a combination of hydrogen and carbon monoxide. Dr Feng said this could unlock the potential of using plastic waste and woody biomass, which under normal circumstances do not degrade in a bioprocess, to produce biomethane. Their results demonstrated that while biofilm reactors have great potential, they require careful control to function optimally at industrial scale.

Dr. Feng says biofilm-based processes offer a robust and flexible platform for future biogas production and that this could become an important contribution to reducing harmful gas emissions while producing renewable energy.

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