Piedmont-based PSNC Energy will begin selling compressed natural gas at two locations in Raleigh with plans for a third in Gastonia. State regulators approved the $1.70-per-gallon price tag. That's about half the cost of gasoline. But you'd have to have a vehicle that uses CNG or to have converted your vehicle to be able to use it. PSNC spokeswoman Angie Townsend says they've had a handful of CNG customers since the early 90's but interest is growing.