Spurred by these findings, the government of Bangladesh took action in the mid-1990s to clear the air. Leaded gasoline, which can pollute groundwater, was banned in 1999. Strict regulations were placed on the sulfur content in diesel fuel. An import ban was placed on two-stroke three-wheelers to help phase out older-model auto-rickshaws, and a widespread CNG program was launched.
Compressed natural gas is “known to be a fuel with lower air pollutant emissions,” says Sameer Akbar, senior environmental specialist at the World Bank. Natural gas is 95 percent methane and releases significantly fewer tailpipe emissions than does gasoline or diesel fuel.
“The combustion of CNG does release more methane than gasoline [does], but those emissions are minor compared with the emissions released from gasoline combustion,” says Andrew Burnham of the US Department of Energy’s Argonne (Ill.) National Lab. Unburned methane itself is a powerful greenhouse gas.
Cheap fuel, expensive conversion