American Petroleum Institute

Leaks Make Natural Gas Vehicles Less Climate-Friendly Than Diesel

(3BL Media/Justmeans) - A couple of weeks back, we wrote about how natural gas was being used to replace diesel to fuel many large trucks. California-based Clean Energy Fuels Corp. opened several natural gas filling stations in locations stretching from coast to coast. We wrote, “Natural gas has become an attractive option for high-horsepower trucks, because it is less expensive (by up to $1.50/gal), cleaner (23% less GHG emissions), and offers better price stability when compared with conventional diesel. It's also better for the health of drivers and the communities in which they operate. Given the high level of natural gas availability in the US at this time, it also offers the opportunity to reduce dependence on imported oil.“

A recent study, just released, reveals some information that could potentially pour cold water on this approach. The study, which was jointly conducted by scientists at Stanford University, the Massachusetts Institute of Technology and the Department of Energy’s National Renewable Energy Laboratory (NREL), found that there is currently 50% more methane already in the atmosphere than had previously been thought. The researchers have determined that this gas must come from leaks throughout the natural gas supply chain.

After conducting a detailed analysis, weighing both the benefits and costs, the team determined that from a greenhouse gas perspective, the added methane resulting from these leaks, more than offsets the reduction in carbon dioxide resulting from the switch from diesel to natural gas. In other words, according to the study’s lead author, Adam R. Brandt, Assistant Professor of Energy Resources at Stanford, “Switching from diesel to natural gas, that’s not a good policy from a climate perspective.”

The leaks, however, were not severe enough to tip the balance when it came to replacing coal-fired power plants with natural gas. That's because of the enormous amounts of CO2 that comes from coal. Even factoring in the methane leaks, gas-powered plants have half the impact of coal plants.

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