Enköping municipality
Close cooperation fuels bioenergy production
Enköping in central Sweden has a unique biocycle process that produces renewable energy via an advanced system linking the municipal heating and sewage treatment networks with local farms. The system runs on renewable energy and actively helps to create a clean environment.
Thinking big
A small town of little more than 20,000 people, Enköping likes to think big in energy terms. Its combined heat and power station supplies enough energy to heat all the town’s houses – and its tap water.
The advanced bioenergy system operated by municipal power company Ena Energi integrates the district heating and waste management systems to provide maximum energy efficiency and environmental gains.
Ninety-eight percent of power plant’s fuel comes from renewable biomass from forest industry waste – branches, treetops, bark and sawmill dust.
Salix plantations yield biomass
Around 15 percent of the biomass comes from short rotation coppice, a fast-growing and species of salix (willow) that produces a high-yield crop for use as biomass.
The salix crops grow in a closed loop-type system that pumps sewage water from the town into dams for purification. The water is then used to irrigate the salix plantations.
The salix benefits the environment by absorbing the heavy metal cadmium and large quantities of nitrogen and phosphorous effluent that otherwise would enter Lake Mälaren. Short rotation coppice is also good at absorbing cesium 137 residues dating back to the Chernobyl disaster.
Cooperation and local production
Cooperation between different partners is at the heart of the Enköping model. The municipality works closely with local farmers, who grow the salix crops and use the ash left behind after biomass incineration as agricultural fertiliser.
Collaboration with farmers is crucial and a key success factor. Energy plantations now grow on more than 1,000 hectares of the municipality’s 53,000 hectares of farmland.
Ena Energi has built eight sludge dams on privately owned farms in the district. In return, the company undertakes to buy salix from the farms’ plantations. All the biofuel used at the Ena Energi plant comes from the local neighbourhood and has an average transport distance of about 70 kilometres.
Ena Energy produces around 220,000 MWh of heat and 100,000 MWh of electricity each year at the Enköping plant.