Truck makers and engineering entrepreneurs alike are racing to build new engines that operate on a variety of non-petroleum-based fuels rarely used in the worldwide heavy commercial vehicle market.

Sweden-based Scania, for example, is making its current heavy truck engines operate on 100% rapeseed methyl ester or RME. After completing long-term tests, Scania said it can now guarantee operating reliability on 100% RME for all its trucks with engines featuring unit injectors. That means most Scania trucks built during the past eight years—some 300,000 vehicles—can use this fuel.

RME is a fuel with diesel-like properties made from rapeseed oil and can be used in Scania's diesel engines without any modifications at all, said Jonas Hofstedt, the company’s engine development manager.

“Compared with diesel, rapeseed fuel has a somewhat lower energy content, which in turn means slightly higher fuel consumption and lower engine power output,” he said. “Also, our own field and laboratory tests show that RME has somewhat higher emissions of nitrogen oxides (NOx), while emissions of carbon monoxide and soot particles are lower than for diesel.”

In the United States, Deland, FL-based Turbine Truck Engines (TTE) is wrapping up design work on a 540 hp detonation cycle gas turbine engine (DCGT) for Class 8 highway trucks in the U.S. that runs on E85 – a blended fuel comprised of 85% ethanol and 15% gasoline. The company noted it’s in negotiations to secure a $10 million dollar equity line of credit to sponsor further development and production of this engine design.

TTE’s DCGT engine is based on the engineering work of Robert Scragg, who developed and invented the electromagnetic isothermal combustion (EIC) process by using the “pulse detonation” of fuel-oxidizer or air mixtures: allowing heavy-duty engines to operate on any type of fuel, be it gasoline, diesel, propane, natural gas, ethanol, or hydrogen.

Yet despite these rapid advances, these experts realize significant challenges remain to replacing diesel with other fuels–especially ones based on organic sources.

“The biggest obstacle for RME appears to be that rapeseed cultivation capacity is insufficient to cover the transport industry's considerable needs,” noted Scania’s Hofstedt. “Calculations show that using all land available for rapeseed cultivation within the European Union would result in fuel production to meet no more than 10-15% of the demand for commercial vehicle fuel requirements. A standard blend of 5% RME in diesel fuel is the most viable prospect today from the environmental and economic viewpoints.”