The findings have implications for truck and engine manufacturers, shippers, fleet operators and policy makers, many of whom look to the operational advantage in carbon dioxide emissions to justify the higher cost and reduced fuel efficiency of a natural gas truck. The challenge is that methane – the main ingredient in natural gas – has 84 times the warming power of CO2 over a 20-year timeframe. Methane is released to the atmosphere at every step from production wells to the vehicle fuel tanks.
“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,” said Jonathan Camuzeaux, a study author and senior economic analyst at EDF. “Otherwise the net warming effect is actually a negative one for 50 to 90 years after the fuel is burned.”
Approximately 6.3 million metric tons of methane escaped from the natural gas value chain in 2013, according to the Environmental Protection Agency’s latest Greenhouse Gas Inventory Report, producing the same 20-year climate impact as about 111 million cars or 140 coal-fired plants. This wasted gas is worth more than $1.42bn, and is enough to meet the annual needs of about 5 million homes.
“Technology moves fast. The time to get ahead of this question is now, before this industry hits a major growth spurt,” said Jason Mathers, a commercial transportation expert working closely with shippers and truck makers in EDF’s Corporate Partnerships Program. “Reducing methane leaks upstream of the vehicles themselves will determine whether a shift in fuels will have a cost or a benefit for the climate.”
Several policies are in play that could improve the climate prospects of natural gas trucks, including upcoming federal fuel efficiency and greenhouse gas standards for heavy trucks and recently announced federal upstream methane regulations. Natural gas vehicles currently use just 0.1 percent of the natural gas consumed in the U.S., but that number could rise significantly as demand for heavy-duty natural gas vehicles grows.
