By some estimates, converting a single city garbage truck from diesel to natural gas can be the equivalent of taking 325 gasoline-fueled cars off the road in terms of reducing emissions.

With that kind of environmental impact and a supply of natural gas at the ready, it is no wonder the idea of using natural gas to power some of the vehicles that travel America’s roadways every day appears to be gaining traction-especially for the largest, least fuel efficient and heaviest emitting vehicles. In fact, one of the key recommendations of the "Pickens Plan" proposed by T. Boone Pickens is using natural gas as the primary transportation fuel for over-the-road tractor-trailers and fleet vehicles.

According to the Pickens Plan, almost 20 percent of every barrel of oil imported into the United States is consumed as diesel by long-haul trucks, which cannot be effectively powered by battery technology. In addition to over-the-road trucks, the plan advocates converting vehicles such as buses, taxicabs, local delivery trucks, and municipal and utility vehicles to natural gas.

"By aggressively moving to shift America's car, light duty truck and heavy truck fleets from imported gasoline and diesel to domestic natural gas, we can lower our need for foreign oil, helping President Obama reach his goal of zero oil imports from the Middle East within 10 years," the Pickens Plan Web site states (www.pickensplan.com).

Advocating natural gas as the bridge fuel to cut the nation's dependence on foreign oil while buying time to develop new energy technologies, the Web site says, "Natural gas is the critical puzzle piece that will help us keep more of the $350 billion-$450 billion we spend on imported oil every year at home, where it can power our economy and pay for our investments in wind energy, a smart grid and energy efficiency."

According to NGVAmerica, there already are more than 120,000 natural gas-powered vehicles on U.S. roads (8.7 million worldwide), and more than 1,100 natural gas fueling stations in the United States, more than half of which are available for public use.

Some 50 manufacturers produce 150 models of light-, medium- and heavy-duty vehicles and engines, and nearly one-quarter of all new transit bus orders are for natural gas, according to the association's Web site (www.ngvc.org).

Natural gas is sold in gasoline-gallon equivalents (GGEs). One GGE has the same energy content as a gallon of gasoline, although NGVAmerica says natural gas costs average one third less than gasoline at the pump. Exhaust emissions from natural gas engines are much lower than either diesel or gasoline vehicles. Even under the U.S. Environmental Protection Agency's new heavy-duty engine emission standards, NGVAmerica notes a natural gas-fired engine produces one sixth the oxides of nitrogen produced by a diesel engine with the same horsepower rating.

Compared with gasoline engine exhaust emissions natural gas vehicles can reduce carbon monoxide by 70 percent, non-methane organic gas by 87 percent, NOx by 87 percent, and carbon dioxide by almost 20 percent, NGVAmerica reports. In addition, natural gas vehicles produce little or no evaporative emissions during fueling which account for at least 50 percent of a vehicle’s total hydrocarbon emissions on gasoline vehicles, according to the Web site.

Excerpted from an article in The American Oil and Gas Reporter