Apart from imported crude, natural gas from Indonesia's West Natuna field arrives at Jurong Island via a 640 km undersea pipeline. Some of it is refined to provide a source of cleaner and cheaper fuel, while the rest is sent to crackers that make other petrochemical products. The country's first refilling station for compressed natural gas (CNG) opened on Jurong Island in 2002. As most of the 2500+ cars running on CNG in Singapore are not allowed to enter the island because the drivers do not have the necessary security pass, four more CNG stations opened on the main island leading up to September 2009.