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To further improve the environment in the Swedish capital, Scania has started full-scale operational trials with six ethanol-fuelled hybrid buses. Sources close to Scania say that the hybrid technology will  reduce fuel consumption by 25 percent. The use of ethanol will reduce net carbon dioxide emissions by up to 90 percent. The trials, run in co-operation with Stockholm Public Transport (SL) and the operator Swebus, are expected to last for two years. During the two-year trial period, the buses will serve one of the more demanding and heavily used lines in Stockholm. Also supported by the Swedish Energy Agency and the Swedish Environmental Protection Agency, the new Scania OmniLink low-entry buses employ a technology where fuel saving of up to 25 per cent are expected. The fact that diesel engines run on ethanol will reduce carbon dioxide emissions by up to 90 per cent compared to a conventional diesel bus.
Göran Hammarberg, Head of Bus Development at Scania, opines that these operational trials will present Scania with a valuable experience of how hybrid technology shapes up in real life, as well as of its environmental effects. "Long-term, hybrid technology will help us reach even more ambitious environmental objectives for urban traffic,” he adds. Scania chose a series hybrid solution for these buses, a technology with the greatest benefits in stop-and-go city driving. What characterises a series hybrid powertrain is that there is no
mechanical connection between the combustion engine and the propulsion motor. Electrical power is generated by a 199kW diesel engine adapted to run on ethanol. Mechanical energy is converted to electrical energy in a generator.
“The six buses are driven by an electrical motor, which offers 150 kW and a maximum torque of 2.750Nm, and doubles as a generator when braking. Energy is stored in supercapacitors with considerably longer service life than today’s batteries. Since the start in 1989, Scania has supplied some 400 ethanol city buses to SL and this has strongly contributed to an improved environment in central Stockholm. Sources at Scania say that the company has regarded ethanol as the most attractive renewable fuel available for city traffic, taking into account factors like availability, infrastructure and proven technology.“
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