Even so, some fleet experts see LNG as a potential replacement to diesel fuel, which is growing in cost and complexity due to regulated emission cuts.

"LNG has historically been used on bigger trucks, but it is a growing fuel for marine and off-road equipment," Howell explained, adding that LNG could be applied to cranes, earthmovers and other heavy-duty machinery.

Off-Road Possibilities

Heavy equipment manufacturers at ICUEE this year currently do not offer an LNG fueling option, but some said they may consider alternatives as the operating costs of diesel engines increases.

"We are investigating various sources of alternative fuels," said Dave Wisniewski, vice president of underground solutions for Pella, Iowa-based Vermeer. Others said they would stick with diesel unless the cost equation tilts more favorably in another direction.

"We're not doing CNG or LNG," said Joe Mastanduno, rental account manager for Moline, Ill.-based John Deere. "The cost of doing it is high, and the volume is really low. But the real issue is fueling infrastructure. It's a niche."

Prior to rolling out its latest line of clean-diesel equipment, Deere experimented with small off-road machines—such as backhoe loaders and skid-steers—that ran on gasoline. In those tests, fleet managers said they preferred diesel power, so Deere ended up downsizing the current diesels to skirt certain emission requirements.

"In the case of the backhoe, we went down under 75 horsepower to avoid a diesel particulate filter," Mastanduno explained. "With these alternative fuels, it ends up that people think about better ways to do diesel."