Unless producers plug methane leaks in "pump to wheels" supply chain, switching from diesel to natural gas will actually increase greenhouse gases, study says. Reductions in greenhouse gas emissions achieved by switching commercial trucks from diesel to natural gas engines will be effective only if fuel providers find a way to plug methane gas leaks in the natural gas supply chain, according to a study coauthored by Environmental Defense Fund (EDF) researchers. "Natural gas trucks have the potential to reduce overall climate impacts compared to diesel, but only if we clean up the highly potent greenhouse gas emissions from the systems that produce and deliver the fuel," Jonathan Camuzeaux, a study author and senior economic analyst at EDF, said in a release. Measured solely on the basis of engine exhaust, natural gas engines are more environmentally friendly than diesel engines, the study confirmed. That result backs up previous findings that have inspired some shippers, logistics service providers, and transportation companies to convert fleets of forklifts and commercial trucks to the cleaner fuel in recent years. However, a full accounting reveals that small leaks during natural gas production, transport, and fueling of individual vehicles combine every year to release millions of tons of methane, which is a far more potent greenhouse gas than the carbon dioxide emitted through fossil fuel combustion in a standard diesel engine. The finding applies to both liquefied and compressed natural gas fuels. If left uncorrected, the climate damage done by methane gas leaks will outweigh the benefits of any reductions in carbon dioxide, researchers contend. That raises questions for truck and engine manufacturers, shippers, fleet operators, and others that are justifying the added cost and reduced fuel efficiency of natural-gas-powered vehicles based on the climate benefits of alternative fuels. Unless methane leaks are stopped, conversion […]