Vaasa biogas busses
There are 12 biogas buses, half the of bus fleet, running the streets of Vaasa. But this is not how it always has been and the journey has been long and complicated. The story starts in 2008 when Vaasa hosted the building fair under the theme smart energy solutions. An ecofriendly public transportation solution with biogas buses were discussed, but the investment costs for new biogas buses would have been to big to private bus actors. Some years later in 2011 an initiative was enrolled by politician Per Hellman to start running the city buses on biogas. The initiative fell in positive terms and pre planning with study visits to Sweden were carried out. In beginning of 2017 the system with biogas upgrading to vehicle fuel quality and filling station for buses and private users was up running.
However, the whole story starts back in 1990 when Stormossen started its biogas production. Back then it was co-digestion of sludge from the Wastewater treatment plant in Vaasa and biowaste from households. Due to problems caused by bad sorting and malfunctioning technical solutions there was a second digester built in 1994, as well as a gas engine for electricity production. With two biogas reactors and several more improvements during the years the chicken-egg dilemma for biomethane production was finally solved with the city of Vaasa in 2014. In 2016 building of the filling station and the biogas upgrading unit was carried out. The biogas upgrading is since then done by an amine scrubber, similar to a water scrubber but uses an amine liquid as catalyzer and heat, instead of pressure changes as in a water scrubber. The big advantage of the amine scrubber is the high methane yield about 99 % methane in the upgraded biogas as well as a very low methane slip <0,1%. Since Stormossen is outside of the natural gas grid by 200 km a back-up solution had to be considered. To be able to offer a 100 % back-up incase biogas production, upgrading unit or compressor station goes down, a LNG-tank and high pressure vaporizer with cryopump came as a solution. The system is only used for back-up purposes but also enables a faster market growth in the future than the biogas production can be extended as well as being able to offer LNG or LBG when the “bigger” trucks arrive in the Vaasa region.