While debate in North America over alternative fuels remains centred on ethanol and biodiesel, the Europeans have added other technologies to the mix. One of the most popular is biogas (methane). Some countries, such as Germany, are giving methane technologies a boost through government incentive programs. As a result, new uses for the fuel are continually popping up.
Volvo’s European truck division announced in March that field trials have just begun on engines that will burn a mixture of 70 per cent methane and 30 per cent diesel. The diesel component will be a blend of petroleum and bio-based fuel, making this a pretty “green” project. Eventually, the company hopes to bump up the methane percentage to 80 per cent.
“Our field tests in 2010 will start with a mixture containing up to 70 per cent methane gas,” says Mats Franzén, manager engine strategy and planning, Volvo Trucks. “We expect to be able to run on up to 80 per cent methane gas once the technology has been refined and tested.”
Eight long-haul trucks will participate in the trials in Sweden; and the program is expected to expand to the U. K. later this year, according to an earlier press release from the company. The intent is to evaluate the engines’ performance and compare them to engines running on conventional fuels.
SAVE MONEY, REDUCE EMISS IONS
Volvo claims these engines will not only reduce carbon dioxide emissions by 80 per cent, but they will also be much cheaper to operate than existing gas versions. That is due in part to the relatively low cost of methane, but also because of the engine’s increased efficiency by integrating diesel technology.
“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 per cent superior to that of the spark plug engine,” says Lars Mrtensson, environmental director, Volvo Trucks. “As a result, this truck consumes considerably less energy than traditional gas trucks do.”
There is already a limited network of methane filling stations in Europe, but it is far from complete. To compensate, the test engines will be able to run solely on diesel, if necessary. That allows the long-haul trucks to operate outside areas of methane supply.
Methane gas is given off by any decaying biological material, which ranges from the contents of municipal garbage dumps to livestock manure, making it a renewable resource. And some proponents say those emissions are released into the atmosphere anyway, so engines burning methane are essentially adding no pollutants to the environment at all.
A SECOND, MODIFIED FUEL SYSTEM
Volvo is modifying its sevenlitre, Euro five-emissions compliant diesel engines for these trials. To make dual fuel work, a second fuel system is added for the methane. It brings the gas to the engine from a separate pressurized tank and injects it into the intake manifold. An engine control module regulates the flow.
To begin the combustion process, a small amount of diesel is injected directly into the cylinder and is ignited by compression in the normal manner. The burning diesel then ignites the methane air-fuel mixture; no spark plugs are required.
“Processors continuously calculate fuel ratio according to the driver’s current driving pattern. The optimum (highest) proportion of gas is achieved during smooth, stable driving,” explains Mrtensson.
According to Volvo, this gives the engine nearly identical performance characteristics to the unmodified diesel version, and the engine will burn about 25 per cent less fuel than a regular gas-only model. There is no word yet on whether trials will eventually include any of Volvo’s off-highway equipment.
With at least one tractor manufacturer, Case IH’s European subsidiary, Steyr, offering a biogas model, it’s possible this technology could gain popularity pretty quickly — at least in that part of the world. If so, methane-diesel engines could someday challenge SCR (selective catalytic reduction) engines for market dominance. SCR technology relies on injecting a urea-based additive into the exhaust stream to minimize emissions.
Scott Garvey is machinery editor for Grainews.
Contact him at [email protected]