For example cattle manure can be used as raw material for recycled fertilizers. Photo: Tapio Heikkilä
Biogas production is based on a multiphase composition process generated by microbes. Several organic raw materials can be utilised such as manure, bio-waste, wastewater sludge, slaughterhouse waste and plant biomass.
The end-products are biogas and a nutrient-rich digestate. The majority of biogas (50-70%) is methane. Methane produced in a biogas plant is a renewable energy source, which can be used for electricity, heat and fuel production.
The potential of biogas from the Helsinki metropolitan area's waste streams is more than 300 GWh per year. This is equivalent to an annual consumption of 25 000 passenger cars.
One Finnish silage bale (650 kg) can produce 80 m3 of biomethane (0.8 MWh). For one natural gas vehicle, this is sufficient for 1300 kilometers.
A centralized biogas plant consists of a multiphase processing chain, including the biogas reactor and e.g. pre-processing, hygienisation and post-processing of digestate.