System analysis

Alternative Power Special Report - Alternative Power Special Report

The type of fuel you use will have different effects on your engine.

January 31, 2017

Photo courtesy of PERC

While gasoline may still be the most popular method of powering equipment, manufacturers have been exploring and investing in R&D and new products designed for propane power. This gives contractors an option to buy a ready-made propane mower vs. using a kit to convert an existing gasoline engine to one that will accept propane fuel.

“Propane has been around in the turf care industry for 20 to 30 years,” says Kohler marketing manager Eric Hudak, who has been responsible for marketing and helping develop the propane engine business.

“It was typically done as an engine conversion that required taking off the gasoline fuel system and mounting a propane tank, and installing an aftermarket propane carburetor and propane regulator.” Currently, only Kohler and Kubota manufacture propane engines.

Hudak says landscape professionals have shared that they tend to change oil less often when running propane.

“There’s a financial benefit of running propane versus gasoline,” Hudak says, adding that propane can save you in excess of 25 percent on fuel expenses.

Some landscape professionals were saving $1,200 per year per mower during high-fuel cost years. “That translates to about $2 per hour compared to a carbureted gas mower,” Hudak says.

With lower gas prices at the pump now, the immediate push to propane is not quite as prevalent as it was when the cost per gallon was near $4, Hudak says.

“The demand for propane seems less intense now with fuel prices down,” Hudak says. “But it’s an opportunity to keep an eye on as fuel prices go up and we are all expecting that to happen.”

Fuel system advances.

Kohler offers an EFI gasoline engine that offers 25 percent fuel savings with gasoline. Now, an EFI propane engine adds more savings on top of that. “You are getting an engine that has been designed and optimized specifically for propane,” Hudak says.

Some landscapers might choose to stick to gasoline, but switch from a carbureted system to fuel injection, says Paul Leech, engineering director at Briggs & Stratton Corp.

By using a quarter of the fuel with an EFI system, you’ll reduce greenhouse gas emissions by 25 percent compared to a carbureted gasoline engine.

“If you are using good, fresh fuel in a gasoline engine vs. propane, the engine durability should not change at all,” says Brett Jury, engineering manager, fuel systems, Briggs & Stratton Corp. “But if you introduce stale gasoline into the system, you can cause damage right then and there.”

Ethanol gasoline creates new concerns in terms of engine longevity and performance, Jury says. Take fuel storage, for example.

“Gasoline is stored in a container where oxygen can get into it, which causes fuel to oxidize and go stale. That used to not be as big of a deal until we started introducing ethanol,” Jury says.

“Ethanol absorbs water, and that can cause fuel to break down and degrade faster than it used to. In that process, it can cause corrosion and gumming, and it can cause bad thing to happen to fuel systems, which can result in performance running stability issues and starting problems.”

That said, Leech notes that propane can offer mechanical benefits compared to a carbureted gasoline engine. “Gasoline can dilute engine oil if it gets mixed in, so propane eliminates the concern,” he says.

“As far as fuel going bad or concerns with ethanol and gumming of jets, the carburetor or injectors, you virtually eliminate those issues so your maintenance can be a big benefit.”

But quality gasoline with a stabilizer running in an EFI engine can give landscape contractors a leg up in the fuel efficiency and performance arena.

“The recommendation we make with ethanol fuels is to either use it, don’t buy more than you’ll use in 30 days, or if you do have fuel that is stored longer, then absolutely put a fuel stabilizer in it,” Leech says.

CNG and Biodiesel.

While Compressed natural gas (CNG) is a growing option in the highway trucking industry, the high-pressure storage tank required and accessibility of the fuel are obstacles for the green industry. Hudak says Kohler has introduced CNG power for home generator sets, but not outdoor power engines.

As for diesel and biodiesel, emission regulations have nearly doubled the size of engines because those control devices are nearly the size of the engines, Leech says. “They’re somewhat problematic from a packaging perspective,” he says.

“There has been a shift in the smaller engine displacements to gasoline and away from diesel.

Making a conversion.

Historically, using propane meant using a conversion kit, and this is still the method many business owners use. They might contract with a third-party or ask their dealer to make the conversion. However, the cost today of conversion via kit versus purchasing a propane engine from the get-go is not all that different, Hudak says.

“When you figure the labor of doing a conversion and the hardware costs, you are typically better off purchasing it outright than doing a conversion.”

For landscape contractors who want to switch over engines they’re already running on gasoline, or convert a new machine that is not yet equipped for propane, Jury says that “a third party is a good choice for our industry, because they will make sure that (the engine) is certified and meets engine regulations.”

marketing opportunities.

Propane has a running advantage for landscape firms operating in areas where sustainability is especially important, Hudek says. Companies in Seattle or Madison, Wisconsin, for example, could market their propane mower fleets as a green advantage.

And in areas that enforce ozone action days, landscapers with propane mowers can still operate. “You can keep working,” Leech says.