Fueling up for cleaner air

Since 2002, Roanoke, Va., has been following a voluntary Ozone Early Action Compact, a state effort to reduce ozone levels and avoid federal sanctions. As part of that plan, the city’s gas-driven lawn mowing equipment would not be used on poor air quality days. As a result, however, crews fell behind schedule maintaining roadsides, medians and other public lawns.

Two years ago, Dwayne D’Ardenne, Roanoke’s acting street maintenance superintendent and landscape coordinator, found a way to avoid mowing delays: using propane-fueled mowers. Emissions from propane-fueled vehicles are low enough that the fuel is typically used for indoor equipment, such as forklifts, but the fuel’s use has been limited for many other vehicles.

Last summer, D’Ardenne replaced three aging gasoline-fueled mowers with propane-fueled EnviroGard zero-turning-radius (ZTR) mowers from Cornelius, N.C.-based Onyx Environmental Solutions. The equipment cost about 10 percent more than traditional mowers, but the fuel savings already have begun to pay off the difference, he says, as the propane has averaged about $2.30 per gallon while gasoline topped $4 this summer.

The mowers use two 33.5-pound forklift tanks, each of which hold about 8 gallons of propane. To replace empty tanks, crews remove them from the mower and replace them with full tanks from the city’s storage facility. “In handling gasoline, you risk spills, which can be hazardous,” D’Ardenne says. “You never have that with propane. Propane’s much safer to handle, and it’s not harmful to soil or water. Gasoline is also highly ignitable, whereas propane is not.”

Roanoke has not changed the frequency of its maintenance schedule for the equipment, but technicians have noticed that the used oil from the propane mowers is cleaner than from the gasoline ones. “You’ve got less contamination, so the technicians should see less wear in the cylinders and the rings,” D’Ardenne says.

Because of the results from using the new mowers, public works officials plan to replace more aging gasoline mowers with propane-fueled versions. “We may well have purchased our last gasoline-powered mower,” D’Ardenne says.

Project:
Propane-fueled equipment

Jurisdiction:
Roanoke, Va.

Agency:
Public Works

Vendors:
Cornelius, N.C.-based Onyx Environmental Solutions; Lynchburg, Va.-based Blossman Gas & Appliance

Date:Summer 2007

Cost:
Approximately $10,000 each