The actual gas production of the WWTP is about 13’400 m3 per day corresponding to 8000 litres of petrol equivalent. This biogas is used for heat and electricity production in a combined heat and power plant to cover part of the process energy of the plant.

An upgrading system, which will be delivered in 2007, shall treat 375 m3/hr of biogas or 9.000 m3/d and produces about 13 m kWh of upgraded biogas per year in a first step. This is abundant to operate about 30 buses. The upgraded gas will be fed to the natural gas grid and transferred to the bus depot where it is compressed to 200 bar. An intermediate gas buffer of a one day load will allow to fill the tanks of the buses in a reasonable length of time and give an operational security. In a first step, 42 slow filling pumping stations will be installed. Until the upgrading plant is installed, green biogas certificates from the WWTP of Lucerne and Basel have been acquired.

In 2005 BERNMOBIL decided to replace the 32 oldest Diesel buses. An evaluation among different departments of the city showed a high interest for biogas buses in order to reduce CO2 emission. An additional impact study demonstrated the positive effect. Thanks to the eco fonds of ewb the higher cost of the gas buses could be covered