Converting vehicles from diesel to natural gas would be “a negative change for climate efforts,” according to Francis O’Sullivan, director of research and analytics at the MIT Energy Initiative. He is a co-author of “Methane Leakage from North American Natural Gas Systems,” a recent report by experts at Stanford, MIT, Harvard and several national laboratories. O’Sullivan spoke about fuel conversion in a recent interview with MIT News.

O’Sullivan’s observation casts serious doubt on government initiatives now under way in New York, Massachusetts and Connecticut that seek to slow climate change by converting heating oil customers to natural gas. That’s because heating oil is already virtually identical to diesel in New York State, and by 2018 the two fuels will be identical in most Northeastern states.

O’Sullivan’s observation mirrors a finding in the Standard-MIT-Harvard study. “For natural gas to beat diesel, the gas industry would have to be less leaky than the EPA's current estimate, which the new analysis also finds quite improbable,” a Stanford University report on the methane study states.

In the MIT News interview, O’Sullivan also discussed the problem of widespread natural gas leakage that adds methane to the atmosphere. “Methane as a molecule is a very potent greenhouse gas — about 30 times more potent than carbon dioxide on a 100-year basis, and much more so over a shorter-term basis. So even small leaks can have a very significant impact on climate change,” he said. 

He also said that the U.S. Environmental Protection Agency (EPA) is under-estimating the amount of methane leakage from the natural gas infrastructure. “Our study synthesized about 200 studies that involved everything from continental-scale atmospheric measurements to measurements of leaks from individual devices. Based on this work, the evidence consistently shows that actual measurements are about 1.5 times greater than what the EPA’s inventorying method suggests,” he said.

The study could change the conversation about the climate benefits of natural gas. “There’s a heated debate now with regard to the climate-change-mitigation benefits of moving from coal to gas in the power system. Although our study found natural gas leaks more methane than previously thought, the shift to natural gas is still a positive move for climate-change-mitigation efforts.

“While a good move within the power sector, the shift to natural gas may not be positive for other sectors, like transportation. Substituting natural gas for gasoline appears to yield no appreciable climate benefits. In the case of diesel fuel, switching to natural gas would actually be a negative change for climate efforts. That’s quite an important implication.”

To read the MIT News article, click here.