While the debate over Marcellus Shale gas development in Pennsylvania continues, there is little doubt that natural gas will play a major role in the state’s economic and energy sectors. Less well-understood, though, is the impact, or potential impact, natural gas could have on the state’s transportation sector.

Positioning natural gas as a transportation fuel becomes a win-win situation by creating more demand for the natural gas being extracted from the Marcellus Shale. And with increased demand, the normal impact of the additional supply of natural gas suppressing prices can be avoided. Added demand for natural gas will keep prices stable, which will encourage ongoing Marcellus development.

Beyond the benefits of creating more demand, burning natural gas in more buses, trucks and cars will result in improved air quality. Natural gas has 95 percent less carbon monoxide than gasoline and 30 percent less carbon dioxide.

Across the United States, natural gas has made inroads as a transportation fuel for city buses and corporate fleet vehicles. Centralized filling stations and higher-mileage vehicles limited to local driving made the city bus and local truck market a natural first step for compressed natural gas.

But the potential to fuel passenger cars, as well, is real — offering lower operating costs and cleaner air.

There are an estimated 12 million vehicles around the world powered by natural gas. But with only about 120,000 of them in the United States, there is growth potential here.

Not surprisingly, the natural gas companies are promoting the idea and pushing for a network of natural gas filling stations. Just last week, EQT Corp. opened Pittsburgh’s first natural gas filling station available to the general public.

Running cars on compressed natural gas is not unrealisitc, despite being fairly unusual in the U.S. today. In 2009, Fiat, which now controls Chrysler, sold 127,000 natural gas-powered cars in Europe. In the United States today, Honda is the only company selling a CNG-powered passenger car.

When it comes to alternative-fuel vehicles, Toyota, General Motors and other manufacturers have focused on hybrid or electric vehicles. In Europe, however, Fiat is a leader in natural gas-powered vehicles, with 80 percent of the market. Fiat’s expertise in natural gas vehicles could be transferred fairly easily to the U.S. market, and CEO Sergio Marchionne has said the company’s alternative fuels efforts will focus on natural gas engines because of the technical challenges still facing electric cars in making them practical and price competitive.

An intriguing idea that eliminates the “range anxiety” that might keep buyers away from natural gas-powered cars is the fact that natural gas-powered cars are considered bi-fuel. And in most of these cars the engine can run on either gasoline or natural gas, with two tanks and a switch allowing the driver to run on either fuel, whichever is available or cheaper.

Despite the controversy over Marcellus Shale, there is a good chance that natural gas will play an increasing role in electricity generation and transportation as a way to lessen the United States’ dependence on imported oil, while at the same time improving air quality.

Natural gas-powered cars, along with hybrids and electric cars, can play an important role in that process. And Pennsylvania is a logical place for Fiat or General Motors, which is reportedly studying the cost-effectiveness of converting some of its car engines to run on natural gas, to launch such a trend.