AVL is the world’s largest privately owned company developing, simulating, and testing powertrain technologies including hybrids, combustion engines, electric drive, batteries, and software for passenger cars, trucks, and large engines. According to Gary Hunter, Director of R&D, AVL is investigating alternatives to diesel for engines in the 75 to 750 hp (56 to 559 kW) range, including hybrids, alternative fuels, and spark-ignition engines.
Unlike on-highway vehicles, many off-highway applications don’t provide adequate opportunities to recharge batteries in a hybrid system. Hunter says most of the applications for energy recovery are limited to hydraulic systems, such as those used in front-end loaders or port equipment.
AVL found that applications such as shovel trucks draw energy from batteries much faster than they replenish it, even when using a large shovel.
“Despite creatively using batteries or capacitors to power accessories, it is difficult to generate and store enough energy to allow hybrid technologies to be commercially feasible,” Hunter said.
“Replacing diesel engines with hybrids is rare and will not happen anytime soon, since in these markets, hybrids offer a minor payback at best. There is a move toward electrification so an engine can operate closer to its peak efficiency range over more of its duty cycle, among other advantages,” he said, “but, electrification is not the only answer.”
Jerry Klarr, AVL’s Director of Strategy for the Americas, says in the next five to 10 years, he sees a potential for engines using natural gas or other liquid fuels such as gasoline, E85, or biofuels with spark combustion systems to make their entrance into off-highway systems.
“Natural gas may be a transition technology, but in markets where it is available, like the U.S. and China, it is a definite alternative if there is an infrastructure in place,” he said. “It offers a potential benefit for both operating and initial costs when compared to conventional diesel.”
AVL has converted diesel engines to natural gas and to SI using liquid fuels for on-highway markets and is in the early development stage of adapting them for off-highway use. Klarr says engines will most likely use compressed natural gas (CNG) before other alternative technologies. Manufacturers could readily adapt heavy-duty on-highway CNG products currently available for off-highway use.
“The off-highway duty cycle is part of the engine challenge, but the real challenge supporting these vehicles is creating refueling infrastructure,” said Hunter.
If an engine is liquid-fueled, refueling is less of a problem. A pickup truck could refill construction equipment while on the job. With CNG, it’s more complicated. CNG refueling involves traveling to a centralized fueling site that has a CNG nozzle or devising a way of getting the fuel into the environment.
AVL is taking on this challenge to find infrastructure and understand the costs of CNG compressors for the engines available for the on-highway market.
“Since it is a low-cost way to refuel while mobile, we expect to see a move toward a broader use of CNG vehicles on-highway that will enter the [off-highway] market,” said Hunter.