Super sludge: Stockholm accelerates waste to CNG plans
Sewage sludge from the Henriksdal plant in Stockholm will be turned into natural gas to cover 40% of the city's CNG fuel needs...
The need for compressed natural gas (CNG) in Sweden is comparatively high, as 60% of public buses already use fuel from renewable energy sources such as biogas, bioethanol or biodiesel.
The Henriksdal plant, owned by municipal water, wastewater and waste management company, Stockholm Vatten AB, currently treats wastewater from around one million inhabitants, extracting biogas from sewage sludge.
Following a contract with Viessmann Group company, Schmack Carbotech, it will now be purified and upgraded to natural gas quality using the pressure swing adsorption (PSA) process.
Through a process of purification, the facility will produce about 180 million kilowatt hours of natural gas quality biomethane annually from the metropolitan area of Stockholm’s wastewater, covering up to 40% of its annual CNG fuel needs.
The company previously built a similar plant for upgrading biogas from organic waste in Sofielund, Stockholm in spring 2015.
The plant has a capacity to upgrade 3,000 m³/hour of raw biogas. The gas that is produced has a methane content of 97% after purification and is used as biofuel in natural gas vehicles.