Gas bus hits the world market

By Svein Tønseth

Buses that run on natural gas with Norwegian technology under their hoods, are on their way into the big wide world. Next stop: Australia.

Scania, the Swedish bus and truck manufacturer, has already entered the international market for gas buses, taking along MARINTEK in the SINTEF Group as a partner. In the course of five years, Scania is to supply Sydney with 250 gas-fuelled buses. Their engines are being built to run on natural gas according to MARINTEK´s "recipe".

Volvo Bussar has also set up parallel lines of collaboration across the Swedish-Norwegian border. Volvo is supplying the city of Gothenburg with gas buses based on MARINTEK´s gas-fuel technology. By the end of 1993, Gothenburg will have 30 gas-fuelled buses that utilize MARINTEK´s technology.

MARINTEK´s fundamental competence in the fields of ignition and combustion technology has played a vital role in building up the institute´s international competitive ability in gas-fuelled engines.

MARINTEK is also collaborating with Trondheim´s local bus company and the Norwegian Ministry of Transport in a Norwegian "environmental bus" project.

MARINTEK´s gas-fuelled vehicles are based on technology that converts diesel engines to what are known as "Otto lean-burn" engines, which have important advantages for the environment: emissions of oxides of nitrogen (NOx) are only 20% of diesel engine emission levels, emissions of soot particles and smells are virtually eliminated, and noise levels are much lower.

"The Otto lean-burn engine is slightly less efficient than a traditional diesel engine. But it is much more efficient, and its NOx emissions are much lower, than the alternative type of gas engine (lambda-1 engine) that is installed in most gas buses in other countries", explains MARINTEK department manager Lars Kolle.

Gas-fuelled Otto lean-burn engines, developed and manufactured in Norway, are already generating electricity in Denmark, Italy, Spain and Norway. Ulstein Bergen delivered the first engine of this type in 1991. By 1993, the company had sold 65 gas-fuelled engines for combined heat and power generation to 42 plants, for a total value of about NOK 350 million.

MARINTEK is also working on gas-fuelled diesel engines, i.e. engines that still use the diesel cycle and burn gas injected at high pressure. The Trondheim scientists have developed an engine of this type for the Finnish company Wärtsilä, which has sold twenty engines to combined heat and power plants in the USA, the UK, Finland, Sweden, Denmark and Yemen.