Linköping
Food waste powers public transport
The city of Linköping in southern Sweden uses food waste from canteens and restaurants to produce biogas. Waste volumes have fallen, the town’s buses have better access to fossil-free fuel and local farmers use the residues left over as fertilizer.
Finding and using the synergies
In 2001 the city authorities in Linköping launched a project to collect and process waste from local canteens and restaurants. The initiative – now an internationally acclaimed success - illustrates how local councils can combine better waste separation with producing renewable fuel and assisting local agriculture.
The Linköping system has launched biogas as a new fuel on the market and inspired many other local authorities to press ahead with equivalent initiatives of their own. In a short time, the produced bio-gas has conquered 7% of the local fuel market for vehicles. The majority of public transport buses are already converted to biogas.
Good for the environment – and profitable too
The project has cut volume of waste sent for incineration in Linköping each year by 3,422 tonnes and boosted biogas production by 1,334,580 m³ – equivalent to 12.65 GWh of renewable vehicle fuel, mainly to be used for public transport.
Annual production of biofertilizer for agriculture has risen by 3,422 tonnes. Phosphorus and nitrogen production for the same purpose has increased by 689 kilograms and 7.1 tonnes respectively. The system allows phosphorus, a finite resource, to re-enter the ecocycle.
Effective implementation
The first step was to install a macerator, a machine that grinds waste into slurry, at Linköping University Hospital and in two school canteens and restaurants, along with a storage tank. From there, the waste is transported to the city’s biogas plant.
Linköping Municipality also installed a central screw press facility in its technical department. The screw press handles liquid foods that have passed their sell-by date and are supplied by manufacturers and wholesalers. The Technical Department plans to purchase a central waste macerator so it can handle large volumes of solid waste such as fruit and vegetables.
Potential benefits for the future
The environmental benefits are clearly visible. Waste macerators efficiently handle organic waste, which is then turned into biogas – an important fuel source in the shift from fossil to renewable.
Biogas produced from food waste and residues prevents a potential waste management problem and can also help to minimize disturbing landfills. Integrated ecocycle-adapted systems of this type can be readily developed in urban settings worldwide.