Pressure test of gas tanks in rack for roofmounting before shipment to Volvo. Eighty years of progress in gas-fuelled vehicles. The truck on the left is from 1917, while the bus operates in 1997. Raufoss Technology's pressure tanks are on the roof of the bus.
Similar buses are in use in Spain, Ireland and Sweden.
Methane is cheap, environmentally sound and available in large quantities. On the other hand, a disadvantage is that it cannot be condensed into a liquid at ordinary temperatures. Gas at 200 atmospheres Volvo has solved this problem by storing the gas in plastic tanks at 200 atmospheres. At this pressure, its energy density is one fifth of that of diesel fuel, but with a total volume of 1m 3 full tanks will take you a good distance. For the sake of protection in the case of a collision, as well keeping the bus doors low for ease of entry, the tanks have been placed on the roof of the bus.