Study: Natural Gas Trucks May Not Be As Clean As Thought
Methane Loss Could Outweigh Environmental Benefits of Conversion
Among fossil fuels, none are cleaner than natural gas -- or so goes the conventional wisdom. However, a study released by the Environmental Defense Fund and Columbia University says converting North America’s heavy truck fleet from diesel to natural gas may not be the environmental panacea that many have assumed. The key factor in the equation and study that throws doubt on natural gas’ green credentials is the unburned methane loss from in-use emissions, refueling, and natural gas infrastructure leaks.
Methane is a powerful greenhouse gas with a comparative impact 25 times as much as carbon dioxide in regards to global warming. While the emissions from burning natural gas are comparatively much cleaner than from petroleum-derived gasoline or diesel fuels, the unburned methane released into the atmosphere from the production, distribution, and refueling of natural gas may outweigh potential benefits of using the fuel in lieu of diesel for heavy trucks.
One technology the study showed as having potential is HPDI engines, which are dual-fuel engines that use a small amount of diesel for a “pilot” but use natural gas as their primary fuel, offering both the emissions benefits of natural gas and the efficiency benefits of compression ignition.
Source: Diesel Technology Forum