Drivers who fuel their vehicles at the Exxon UniMart on Route 309 in Walberts, South Whitehall, may have noticed a different type of fuel pump.

According to Ann Marie, day manager at the store, many motorists pull up to the pump and think it's gasoline.

But it's not.

The pump is the first Compressed Natural Gas filling station in the Lehigh Valley.

Owned by Lehigh Gas Company, headquartered on Hamilton Street, Allentown, it took the company some time for the Environmental Protection Agency and South Whitehall Township to approve its installation.

With more than 120,000 CNG vehicles in the U.S. and 15.2 million worldwide, according to the Natural Gas Vehicles for America organization, there are, however, only more than 1,000 CNG fueling stations in the U.S.

About half are open to the public. The rest serving fleets such as cabs, trash trucks, buses and airport shuttles. But that number continues to grow as it has here in the Lehigh Valley.

According to Sil Lutkewitte, Lehigh Gas CNG representative, his company has additional fueling stations in King of Prussia, Concordville and two near Philadelphia International Airport with plans for more.

CNG is a natural gas under pressure, which remains clear, odorless and non-corrosive.

Although vehicles can use natural gas as either a liquid or a gas, most vehicles use the gaseous form compressed to pressures above 3,100 pounds per square inch.

The gas is stored in thick-walled steel, aluminum or composite tanks built to last more than 20 years, according to the Consumer Energy Center.

As for its safety aspect, when released, CNG will mix with air and become flammable only when the mixture is within 5 percent to 15 percent natural gas.

When the mixture is less than 5 percent natural gas, it does not burn. When the mixture is more than 15 percent natural gas, there is not enough oxygen to allow it to burn. And because natural gas is lighter than air, it quickly dissipates when released from tanks.

CNG comes from three types of wells: natural gas, condensate and coal bed methane wells. Well-extracted natural gas, however, requires a cleaning process before it can be used in vehicles.

While natural gas is relatively new to the U.S., foreign countries have been using it for years. Iran is the largest user, followed by Pakistan, Argentina, Brazil, India, Italy, China, Columbia, Uzbekistan and Thailand.

CNG vehicles are good choices for high-mileage centrally-fueled fleets that operate within a limited area.

Their primary advantages are it costs about 50 percent less than diesel fuel or gasoline.

At Walberts UniMart Exxon, recently, it was selling for $2.19.9/GGE (Gas Gallons Equivalent), it's clean burning, less corrosive than gasoline and reduces emissions up to 90 percent compared to diesel fuel or gasoline.

Mileage ratings are about the same for gasoline or CNG, with CNG likely offering 1 gallon per mile highway mpg better.

Consumer vehicle choices are limited at this time.

So far, only the Honda Civic, Chevrolet Silverado 2500/GMC Sierra 2500 HD, Dodge Ram 2500, Ford F250/F350 pickups trucks and GM Cargo Vans are CNG equipped.

There are also conversion kits available for other passenger cars.

When buying one of these vehicles, Pennsylvania residents may qualify for tax incentives as per Gov. Tom Corbett's Act 13 legislation that would allow this as long as there are funds available.

In comparison to a gasoline pump, CNG uses a different nozzle with a smaller opening so it will not fit into a conventional vehicle gasoline filler hole.

And, there are a couple more steps involved before pumping, but they are all explained on the pump's panel.

What may not be seen at first at the UniMart station is the heavy-duty piping and space ship type sphere to the rear of the store where the CNG is stored and pumped underground to the filling pump.

If gasoline prices again start to rise, CNG may become the fuel of the future.

CNG powers vehicles with the same, but modified engine components, as gasoline does, so operation is unnoticeable to the driver.

To locate a CNG station, go to CNGnow.com. for an iPhone/Android app listing of locations, pricing and pressures.