Of all the alternative fuels used in cars and trucks, natural gas - either compressed natural gas (CNG) or liquefied natural gas (LNG) - offers the biggest cut in emissions compared to gasoline. Typically, CNG is used in light- and medium-duty vehicles while LNG is available only for commercial customers in heavy-duty vehicle applications.
The driving range of a natural gas vehicle depends on engine displacement, vehicle mass, fuel economy, and of course on driving habits. Overall, a dedicated natural gas vehicle, running only on CNG, offers a substantially shorter driving range than its gasoline counterpart - typically 120 to 200 miles. It's simply not possible to package enough bulky gaseous fuel cylinders onboard a vehicle to store the same amount of energy as in a conventional gasoline tank. This storage issue finds cylinders located beneath a vehicle and sometimes in a sedan's trunk, just behind the rear seatback, which sacrifices some cargo space.
Bi-fuel vehicles resolve the range issue by storing both gaseous fuel and gasoline onboard, thus allowing a vehicle to run on either. Of course, running on gasoline doesn't achieve the same emissions reductions as natural gas, so the goal is to run on CNG whenever possible and gasoline only as if necessary.
While much greater energy can be stored onboard a vehicle in LNG form and thus a greater driving range can be provided, this liquid fuel must be stored and dispensed at -260 degrees F, which presents safety and handling issues that relegate it to commercial use only.
CNG is available at nearly 200 natural gas fueling stations in California, with more than half offering full or limited public access, and at more than a thousand stations nationwide. They include facilities at some gasoline service stations under contract with gas utility companies. While this may seem a large number, it pales in comparison to the approximately 170,000 gasoline stations conveniently located across the country.
Natural-gas vehicles typically cost about $4,000 to $5,000 more than gasoline-powered models.
