Thursday morning saw San Antonians test-driving lawnmowers at Mission San Juan National Historical Park.

All of the lawnmowers were propane-powered, which is often touted as a cleaner-burning fuel. Machines from different companies were showcased courtesy of a federal program called “Clean Cities,"

The group’s aim is to encourage cities to look to alternative fuels.

"On those days when we have those air quality health alerts, the mowers and these vehicles are actually safe to use,” said Yliana Flores, who serves on the Alamo Area Clean Cities Coalition, a division of AACOG.

In fact, propane mowers do reduce green house gases and, according to Jim Lawton, a representative of Briggs and Stratton and Ferris Lawnmowers, they are also practical.

"The engines breathe better with it and virtually run better on it," said Lawton.

Proponents also tout that propane mowers eliminate gasoline spills and cost less when it comes to fuel.

"On a refill system for our customers, they’re looking at about $2.30 a gallon, as opposed to $3.75 for regular gas and $4 now for diesel fuels," said Lawton.

According to AACOG, propane mowers have fewer emissions than typical gasoline mowers, something that attracted the San Antonio Missions National Park Service. They now use propane mowers to cut grass across the park.

"We want to raise an awareness of how propane fueled vehicles are just good for the environment,” said San Antonio Missions National Historical Park Superintendent John Lujan.

Propane lawnmowers cost about 20 percent more and are generally more efficient for commercial use, but supporters believe higher costs will be made up in cheaper fuel prices.

The Texas Propane Council also offers rebates to businesses that update their fleet to propane.