New wastewater treatment plant uses sewage to produce climate-friendly shipping fuel

A consortium linked to the Karlsruhe Institute of Technology (KIT) has built a plant at the Mannheim wastewater treatment plant that cleans generated biogas and uses the resulting CO2 to produce climate-neutral marine fuel using green hydrogen. The process could help decarbonise the shipping sector, which is currently responsible for around three percent of global greenhouse gas emissions.

The demonstration plant uses a patented process to convert biogas produced during wastewater treatment into climate-neutral methanol. The biogas is first purified and the seperated CO₂ can then be used with renewably-produced hydrogen to make methanol – a raw material that can be used as marine fuel or in the chemical industry. Methanol does release the CO2 back into the atmosphere when burned. However, because the carbon comes from the treatment plant and not from additional fossil sources, it is considered climate neutral.

There are some 80,000 wastewater treatment plants in Europe that offer considerable potential for the new process, wrote KIT. "To achieve our climate protection goals, we must keep all technological options open," said Volker Wissing, federal minister for digital affairs and transport. “In addition to electrification and hydrogen-based propulsion, we need climate-friendly fuels, especially in maritime shipping." Stressing that the sector represented a future growth market, Wissing said Germany should play a pioneering role in research and development. "It's also about making our country independent of energy imports."

Vidal Vazquez, co-founder of climate tech start-up ICODOS, a spin-off from the KIT, added, "In Germany alone, wastewater treatment plants could produce several million tonnes of sustainable methanol annually." The project shows that "wastewater treatment plants can serve as the heart of sustainable fuel production – a potential that has so far remained untapped," Vazquez said. ICODOS is currently in discussions with other wastewater treatment plants to set up other production facilities.

Renewables-based synthetic fuels could be necessary to decarbonise certain sectors such as shipping, where alternatives are not available today, or extremely costly. However, producing the rare fuels is energy-intensive and expensive and they should only be used where the direct use of electricity is not an option.