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A Kyoto University spinout and Japanese water treatment company have launched a proof-of-concept trial aimed at producing electricity and high-purity carbon dioxide (CO2) from sewage sludge without combustion.
Rhinoflux and Swing Corporation began the demonstration in July 2026, following a feasibility study into the use of Rhinoflux’s proprietary Hydro Chemical Looping (HCL) technology for sewage sludge.
The companies said the trial will assess the potential to turn sewage sludge generated at Japanese wastewater treatment facilities into an energy and carbon resource, with the process designed to simultaneously generate power and capture CO2 at more than 99.9% purity.
Rather than burning the biomass, the technology uses chemical reactions in an aqueous solution to convert its organic content into electricity and separate CO₂.
The approach is suited to high-moisture feedstocks such as sewage sludge, which can be challenging to use in conventional biomass power generation because of the energy required to remove water.
Japan produces an estimated 2.34 million tonnes of sewage sludge on a dry-solids basis each year, creating an ongoing challenge for treatment, transport and disposal.
Existing routes include incineration, landfill, anaerobic digestion and use in construction materials, but Rhinoflux and Swing see potential to add value by recovering both energy and CO2 from the waste stream.
For gas users, the potential CO2 output is a key part of the proposition.
Rhinoflux said its HCL process can separate CO2 at greater than 99.9% purity alongside power generation. The captured gas could potentially be used as a feedstock for industrial applications, including liquefied CO2, while the companies also see potential for the biomass-derived CO2 to contribute to carbon dioxide removal markets.
The technology has previously been demonstrated with other biomass feedstocks. In a separate collaboration with Sumitomo Forestry, Rhinoflux reported more than 120 hours of continuous operation of a 1 kW demonstration unit, with stable power generation and CO2 capture at 99.9% purity.
The company subsequently reported more than 240 cumulative operating hours across multiple biomass feedstocks.
Rhinoflux has positioned HCL as an alternative to conventional biomass combustion, claiming power-generation efficiencies of 45 to 65%, compared with around 10 to 30% for conventional combustion-based biomass systems.
The company is targeting commercialisation of 100 kW-class plants from 2028, with larger 10 to 100 MW projects also envisaged.
The sewage sludge trial will now focus on gathering operational data and assessing the requirements for deploying the technology at wastewater treatment facilities.
