Study: NG not necessarily cleaner as truck fuel

WASHINGTON (May 21, 2015) — Switching to natural gas from diesel as a truck fuel could prove harmful to the environment unless methane leakage is lowered, according to a new study published May 20 in the journal Environmental Science and Technology.

The study, “Influence of Methane Emissions and Vehicle Efficiency on the Climate Implications of Heavy-Duty Natural Gas Trucks,” was conducted by scientists at the Environmental Defense Fund and Columbia University's Lenfest Center for Renewable Energy.

“Under our reference care assumptions, reductions in CH4 (methane) losses to the atmosphere are needed to ensure net climate benefits on all time frames when switching from diesel to natural gas fuel in the heavy-duty sector,” the report said.

Combining reduced methane losses with engine efficiency improvements could provide substantial environmental benefits with natural gas, according to the report.

“However, until better data is available on the magnitude of CH4 (methane) loss — especially for in-use emissions — the precise climate impacts of a switch remain uncertain in this sector,” it said.

The new report shows the importance of understanding all the issues involved with alternative fuels before rushing to use them as replacements for traditional fuels, according to Allen Schaeffer, executive director of the Diesel Technology Forum.

“As the authors suggest, this report does raise serious questions about whether large-scale moves to natural gas as a transportation fuel is truly a climate-positive consideration, or a move that could make things worse,” Mr. Schaeffer said.

On the other hand, Ryder System Inc., on its website, promotes the use of natural gas for its truck fleets. Offering a white paper available on the site, the company states that “natural gas is gaining traction as an alternative fuel. Here are the reasons why: Natural gas is an abundant domestic resource that is cost effective and also better for the environment.

“Adding natural gas vehicles can also be a competitive advantage and help you benefit from significant tax relief.”

The company claims adding natural gas to a fleet can help reduce fuel costs, is a fuel that runs clean, lowers CO2 emissions by up to 25 percent, is as safe or safer than diesel fuel, can support a company's sustainability initiatives and can provide a “marketing advantage.”