North Carolina's natural gas industry is pushing ahead with a strategy to promote cars powered by compressed natural gas.

Piedmont Natural Gas has four compressed-gas pumping stations - in Charlotte, Greensboro, Greenville, S.C., and Nashville, Tenn. - and plans to add four or five more in the Carolinas this year, catering initially to fleet vehicles.

Gastonia-based PSNC Energy asked regulators last week to approve a rate PSNC would charge to motorists filling up at PSNC-owned filling stations. PSNC, which also serves the Triangle, is planning to open three stations in the state this year.

The two natural gas utilities would compete with electric utilities such as Duke Energy, which are promoting electric vehicles that recharge from public charging stations and home-charging stations.

The cost of compressed natural gas fuel fluctuates with market conditions but is generally less than half the cost of gasoline.

Nationwide there are about 1,000 stations for compressed natural gas, mostly in California and the Midwest, and most of the users are government and industrial truck and transportation fleets.

PSNC had previously asked the N.C. Utilities Commission to be allowed to offer financing to homeowners and businesses that want to install their own natural gas pumps, which can cost about $7,500. The commission is expected to approve the request.

Cars powered by compressed natural gas, or CNG, are among the most economical in the world. The American Council for an Energy-Efficient Economy has ranked the CNG Honda Civic as the greenest car in America for the past eight years. Natural gas is the cleanest-burning fossil fuel, producing virtually no mercury and half the greenhouse gas output of coal-burning power plants, the main fuel source for electric cars.

CNG cars are rare, however, largely because of the near-total lack of infrastructure to get them refilled. Honda produced just 990 of its Civic GX models this year and plans about 2,000 for the 2012 model year.

Conversions are also an option, albeit a costly one, creating dual-fuel cars that run on CNG or gasoline.

PSNC is requesting approval for a proposed CNG rate of $1.11 in gas-gallon equivalents. However, the retail rate would come to about $1.79 with taxes and other fees.

Piedmont Natural Gas is approved for two seasonal rates ($1.04 and $1.06 in gas gallon equivalents), but customers pay $1.63 after taxes and fees. Its Charlotte station is at the company's operations center at 4301 Yancey Road. While open to the public, Piedmont asks that people who want to use the station call the company in advance at 800-752-7504.

Observer Staff Writer Bruce Henderson contributed.