Ten years ago, the Stockholm region set an ambitious target to run all land public transport on 100% fossil fuel-free fuel by 2025, but buses powered by ethanol and RME (rapeseed methyl ester) contain some percentage of fossil ingredients, therefore, the total number of buses will not be 100% fossil fuel free, as fossil components are needed to start the engine or enter the production process. However, buses that run on electricity, biogas or HVO (hydrogenated vegetable oil) will use 100% fossil fuel-free raw materials. The target was already met in September 2018, seven years ahead of schedule.
Breakdown of environmentally classified Stockholm buses by fuel:
(RME and HVO = biodiesel)
- Proportion of buses running on RME (rapeseed methyl ester) and HVO (hydrogenated vegetable oil): 80%.
- Share of buses using biogas: 15%.
- Ethanol buses: 4.5%
Biogas production produces renewable energy from virtually all organic matter. Biogas is produced from raw materials from plant life (such as rapeseed oil, sunflower oil, sugar cane or tall oil) and biological waste (such as fat, slaughterhouse waste, old food waste or toilet waste). Organic waste is collected at household level.
Scandinavian Biogas has been operating the gas upgrading plant at Henriksdal's wastewater treatment plant since the end of 2010. In 2016, the capacity of the plant was further increased by the completion of a new gas upgrading line.
During the year, raw gas production was increased by gradually increasing the organic loading of the digester of the wastewater treatment plant.With the new line, upgrading capacity increased from 7.5 million in 2015 to 20 million standard cubic metres of biogas fuel (approximately 97% methane). At this site, raw gas is upgraded thanks to two upgrading plants that use water scrubbing technology (HVAC) and pressure swing adsorption (PSA) technology.
