Sewage from cargo ships turned into biogas in Finland

A new project producing biogas from sewage discharged by cargo ships is underway in Finland.

The Baltic Sea Action Group (BSAG) is collaborating with multiple companies, including Gasum, on the new Ship/t Waste Action project. The initiative turns sewage into biogas that will be used as fuel by the heavy-duty transport sector.

The Ship/t Waste Action cooperation develops waste value chains between different parties. The Port of HaminaKotka, the largest general port in Finland visited by around 2,500 cargo ships annually, has been chosen as the first location.

“We want to encourage ships to discharge their wastewater at the port,” said Suvi-Tuuli Lappalainen, development manager at the Port of HaminaKotka. “Our sewage reception and treatment facilities meet the requirements of the circular economy.”

Regional wastewater and sewage treatment company Kymen Vesi treats the sewage discharged by cargo ships at the port of HaminaKotka. The wastewater sludge created in the process is then refined into renewable energy at Gasum’s biogas plant.

“We can achieve our objective of a cleaner Baltic Sea, one ship, one port, and one country at a time,” said Elisa Mikkolainen, project director at BSAG. “The nutrient load on the sea decreases every time wastewater is discharged at the port. We need extensive cooperation to succeed in our mission.”

Wastewater and food waste contain, among other things, nutrients, bacteria, fats, chemicals and microplastics. If these are discharged into the sea, they accelerate two of the worst issues currently facing the Baltic Sea: eutrophication and oxygen depletion.

Approximately 2,000 ships are operating in the Baltic Sea, and 95% are cargo ships. It is currently legal to discharge grey water, sewage and ground food waste into the sea. Passenger ships, such as the ferries between Finland, Sweden, and Estonia, have been voluntarily discharging their wastewaters at the port for years. Since 2021, the International Maritime Organisation regulations prohibit discharges of untreated sewage from passenger ships in the Baltic Sea; there is no similar regulation for cargo ships.