If you combine some biogas with a splash of biodiesel, what do you end up with? Well, we're not chemists, but we'd venture to guess that the end result is a splendid fuel mixture that's eco-friendly, clean burning and, when fed into a bus engine, can increase its efficiency dramatically. Okay, that's not really a guess, since that's what Volvo Trucks recently confirmed. The company has spent years developing the 8500 intercity bus, a product tailor made to run on this biogas-biodiesel concoction and the hard work is starting to pay off.

Vårgårdabuss, in Sweden, placed the first order for Volvo's dual-fuel 8500 intercity bus and was apparently so impressed with the claimed efficiency and clean-burning properties that it went ahead and ordered 11 of them. The buses will swing into service by July 2011.

The 8500 is designed to operate either on a biogas-biodiesel blend or on biodiesel alone. It matters not which fuel enters the bus' engine, but typical blend rates call for 70 percent biogas and 30 percent biodiesel. But let's say that you lack access to the bio-varieties of either fuel. Then what? The 8500 intercity won't get choked up if its pumped full of some natural gas (methane) or conventional diesel, but Mother Nature's wince might do you in.

[Source: Volvo Trucks]


Volvo: Volvo's First Order for Methane/Diesel Buses

"In a time when we must reduce society's total energy consumption, higher utilization of the diesel-engine technology is an important development."

Volvo (STO:VOLVA)(STO:VOLVB) has received its first order for buses that operate on both biogas and diesel. Using diesel technology increases environmental efficiency compared with current gas-operated buses.

Biogas is a renewable fuel that contributes to reducing greenhouse-gas emissions. Many cities and regions are investing in expanding the production of biogas for heating and vehicle fuel. Many gas-operated buses currently use biogas as fuel.

However, current gas-operated buses have some disadvantages. It is a complicated technology that requires careful maintenance. Furthermore, current gas-operated engines are based on the same technology as gasoline engines, the Otto cycle, which is not as energy-efficient as diesel-engine technology.

"A diesel engine is 30-40% more efficient than current gas-operated engines," says Edward Jobson, Environment Director at Volvo Buses. "In a time when we must reduce society's total energy consumption, higher utilization of the diesel-engine technology is an important development."

Consequently, AB Volvo is participating in a demonstration project for methane/diesel technology using buses for regional traffic and trucks. Current diesel engines will be used, but up to 70% of the fuel is biogas or natural gas. The Swedish Energy Agency is contributing nearly SEK 24 M to the project.

With respect to the buses, a common diesel bus will be used, on which gas tanks will be mounted on the roof and equipment that injects the gas into the engine to create an optimal mixture of air and fuel.

The diesel engine functions as usual, but only a small amount of common diesel or bio-diesel will be continuously injected into the cylinders. The diesel's task is to function as a type of ignition for the gas, which is the primary fuel. At the same time, the operators will feel safe knowing that the engine can operate as usual on only diesel if the gas tank is empty.

The gas will be stored in the tanks in a gaseous state, as with current gas-operated buses and refilled in exactly the same manner from the same filling stations.

Volvo Buses has now received its first order for 11 buses, with methane/diesel technology, from Vårgårdabuss in Sweden, for putting in service in July 2011. It involves the Volvo 8500 intercity bus model.

"For some time, we have been able to offer our Volvo 7700 low-floor bus with gas-operated engines," says Martin Spjern, Head of Volvo Buses' Sweden operations. "Now, we will also be able to offer a low-entrance bus for regional traffic, which can operate mainly on gas.

"Our customers will have access to a bus that combines the efficiency and reliability of the diesel engine with the environmental advantages achieved with gas operations."

October 26, 2010

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Volvo Bus Corporation is one of the world's largest manufacturer of large buses and coaches. The range comprises complete vehicles, chassis, bus bodies, transport system solutions for metropolitan traffic, leasing, financing and service contract maintenance. Volvo Bus Corporation is part of the Volvo Group, one of the world's leading manufacturers of trucks, buses and construction equipment, drive systems for marine and industrial applications, aerospace components and services. The Group also provides complete solutions for financing and service. For more information, please visit http://www.volvobuses.com/

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