While natural gas is a viable alternative fuel for some fleets, it doesn't necessarily work for every application. The high cost of investment for fueling infrastructure can be a barrier for smaller fleets that do not put enough miles on their vehicles to see a rapid return on investment with a natural gas fleet. For some of these fleets, propane autogas may be a good alternative.
"Both propane autogas and CNG (compressed natural gas) are clean, domestic, plentiful energy sources, but the way they integrate and operate related to trucks and buses is much different," says Todd Mouw, vice president of sales and marketing for ROUSH CleanTech.
ROUSH CleanTech (roushcleantech.com) is an industry leader of alternative fuel vehicle technology.
A fleet can move to propane autogas with a much smaller upfront cost than natural gas vehicles. Unlike natural gas, which operates as a gas, propane operates as a liquid under low pressure, and this pressure difference can lower the cost of fueling infrastructure. Because propane autogas stations cost less to install, they are also more readily available with present public fueling infrastructure, Mouw says.
Both propane autogas and CNG offer much lower NOx and particular matter emissions than pre-2010 diesel engines.
"Both propane and CNG are the right step away from diesel," Mouw says. "They are clean, domestic and offer better total cost of ownership as compared to diesel."
Propane autogas typically does not require maintenance shop modifications as long as the shop is up to code for gasoline or diesel maintenance. Many fleets save on maintenance costs compared to their diesel vehicles, because there is no DEF, no aftertreatment systems and fewer quarts of oil per oil change, Mouw says.
"Propane autogas fuel systems are actually less complex compared to diesel or CNG, so technicians can easily be trained by an OEM or aftermarket fuel system manufacturer to maintain, diagnose and repair engines," adds Michael Taylor, director of autogas business development for the Propane Education & Research Council (PERC).
For fleets that operate locally and put high mileage on their vehicles, particularly if they are operating Class 8 vehicles, CNG may offer a better ROI and be worth the infrastructure investment.
"CNG works better on the larger, Class 8 vehicles that have more real estate to package enough tanks to provide adequate range," Mouw says. "These vehicles usually burn enough fuel to justify the significant fueling and maintenance shop investments."
For Class 4 through Class7 vehicles and school buses, he adds, propane autogas is a good fit because of the low upfront cost and more accessible fuel infrastructure.
"Incorporating propane autogas into a fleet doesn't take a lot of work," Taylor says. With a little investment, fleets that are too small to benefit from natural gas may be able to realize cost savings and lower emissions by switching to propane autogas.
