Sweden’s Volvo Trucks will be testing a biomethane gas truck that increases energy consumption compared to traditional gas trucks while providing the same power and driveability as a diesel vehicle. The trucks will be tested in Sweden and Great Britain in 2010.
“This unique technology allows us to combine the advantages of gas with the diesel engine’s high efficiency rating, which is about 30 to 40% superior to that of the spark plug engine,” commented Lars Martensson, environmental director - Volvo Trucks. “As a result, this truck consumes considerably less energy than traditional gas trucks do.”
The trucks, which meet Euro 5 exhaust emissions standards, will be fuelled by a mixture of methane gas and diesel fuel, including biodiesel. Both natural gas and biogas consist of methane, but natural gas is a fossil fuel while biogas is produced from biodegradable material such as waste.
“Methane gas is by far the most accessible fuel as an alternative to diesel,” said Martensson. “There are larger reserves of natural gas than oil. But above all, production of climate-neutral biogas is gaining momentum in many countries, which solves the most urgent problem, reducing CO2 emissions.”
Special tanks for gas operation are added to the test trucks for either liquid volume-efficient methane (liquefied natural gas or liquefied biogas) or pressurized methane gas (compressed natural gas or compressed biogas). In addition, a separate fuel system is added with gas injectors in the inlet manifold, Volvo said.
To fire up the engine, rather than using a spark-ignited engine that traditionally restricts the operation range of the vehicle, a small amount of diesel is injected into the tank and ignited by compression which in turn ignites the methane gas/air mixture. According to Volvo, this process allows the vehicle to maintain operating characteristics of a diesel truck.
“We expect to be able to run on up to 80% methane gas once the technology has been refined and tested,” sayidMats Franzen, manager of engine strategy and planning. “Our field tests in 2010 will start with a mixture containing up to 70% methane gas. The remainder will consist of bio-mix diesel, i.e. fossil diesel mixed with diesel produced from renewable raw materials.”
The truck is further economized with processor technology that calculates the needed fuel ratio based on the driving pattern of the truck. “The optimum - i.e. the highest - proportion of gas is achieved during smooth, stable driving,” explained Martensson.
If the gas runs out, the truck is able to switch over to full diesel operation and continue its run.
According to Volvo, the effect of this technology on the fuel chain could reduce carbon dioxide emissions by up to 80% in the long term compared to traditional diesel operation if biogas and 100% biodiesel are used.
In 2007, Volvo Trucks embarked on developing seven demo trucks running different biofuels. This type of vehicle is one of two technologies the company has chosen to focus on at this point. The other, DME, or dimethyl ether, is a technology that Ford Europe is also looking at.
Chemical giant Chemrec AB is beginning work on a “BioDME” plant in Sweden that uses a “black liquor gasification technology” to make DME from organic refuse produced by the forestry industry. “Black liquor” is a waste stream of the pulping process, notes Richard LeBlanc, CEO of Chemrec USA, adding that the company’s Piteå, Sweden, plant is expected to be producing DME and methanol by next year.