Public concern over auto emission pollution problems in Salt Lake, Davis and Weber counties may be the catalyst Mountain Fuel Supply has been looking for to convince companies with large vehicle fleets to convert those cars and trucks to compressed natural gas fuel systems.

Experience elsewhere in the United States and around the world shows that natural gas emissions are 50 percent to 90 percent less than those created by conventional gasoline and diesel fueled vehicles. It's not a new concept, but it is one whose time may have come.Mountain Fuel has had 23 vehicles operating on compressed natural gas since 1983. The company has implemented a full-scale conversion program and will have 100 company-owned cars, vans, pickup trucks and four-wheel drive vehicles operating by the end of the year.

The company is also launching a test program with local businesses to urge large fleet owners to consider the natural gas alternative. By the end of summer, five Salt Lake companies will have between two and 10 vehicles each using natural gas on a test basis.

"We have two goals in this proj-ect," said Mountain Fuel spokeswoman Susan Glassman. "First, we want to help with the clean air problem and second, we see a great sales opportunity."

Gordon Larsen, who oversees the natural gas vehicle program, said the fuel is actually safer in addition to being cleaner. He said the fuel has a lower flash point than either gasoline or propane.

And, there are other environmental advantages. Underground storage tanks are eliminated and trucks do not have to ply the highways delivering the fuel to fuel stations. A compressor and meter is simply attached to existing natural gas lines and the fuel station is ready to go.

Glassman said the company estimates the cost of natural gas fuel at about 60 to 70 cents per gallon when compared to gasoline prices. She said that includes the cost of the compressor and other equipment. Converting a vehicle to use natural gas costs about $2,000.

Larsen said the conversion equipment is an add-on feature, eliminating the need to alter existing engines. In fact, converted vehicles can usually operate on either natural gas or gasoline, requiring only a flip of a switch to make the change.

The biggest limitation for natural gas powered vehicles is range. Since most hold only the equivalent of five to six gallons of gasoline, the range is limited to about 150 miles.

Glassman said Mountain Fuel has joined with the Utah Energy Office and the Utah Transit Authority in an attempt to attract federal funding for five buses that will operate solely on natural gas. Larsen said there is advantage to having engines designed to work specifically on natural gas.

"The octane rating on natural gas is about 130 which almost triples the horsepower it can generate," Larsen said.

Other factors that favor natural gas only vehicles is the reduced engine maintenance. Larsen said oil changes can be extended to 20,000 miles when natural gas is the only fuel used because there are no contaminants created when the fuel burns.

Mountain Fuel has just completed a filling station at its complex on First South in anticipation of the increased use and the test agreements with local businesses. He said the test programs will be used to collect data for use in promoting the program on a larger scale in the future.