Mammoth Cave National Park in Kentucky has partnered with the U.S. Department of Energy's (DOE) Clean Cities National Park Initiative to deploy new vehicles powered by propane autogas.

"Each year, approximately 175,000 visitors ride a bus as part of their cave tour. On a busy summer day, buses travel more than 400 miles within the park. Using propane instead of gasoline greatly reduces emissions and the park's carbon footprint, and park visitors get a better understanding of how alternative fuels can reduce the country’s dependence on oil," explains park superintendent Patrick Reed.

For a number of years, Mammoth Cave has worked with the Kentucky Clean Fuels Coalition to roll out alternative-fuel vehicles. This latest project - which was backed by $505,000 from the DOE - involved the replacement of four propane buses, as well as the purchase of two propane pickup trucks and one electric vehicle from Global Electric Motorcars.

The National Park Service notes that Forever Resorts, Mammoth Cave's concessioner, also runs a propane-powered bus fleet.