A study released today by the Center for Alternative Fuels Engines and Emissions at West Virginia University examines data collected on methane emissions of natural gas engines from "pump-to-wheel," meaning from natural gas fueling stations and heavy-duty vehicles themselves.
As natural gas vehicles become more prevalent, they have the potential to release fewer fossil fuel emissions than diesel fuel - if methane levels can be controlled. The study shows that the exhaust pipe and a part of the vehicle called the crankcase are the sources of the highest levels of methane emissions.
"Some of the methane can be arising from leaks - most of natural gas, is, in fact, methane - from leaks, from plumbing, from losses of small volumes of the gas when you're refueling the vehicle," said Nigel Clark, the George Berry chair of engineering at WVU and the lead author on this study. "And some of it of course can come out of the vehicle's tailpipe as unburned fuel."
Methane is a greenhouse gas emission and is unique to natural gas. CAFEE decided to collect data on pump-to-wheel methane emissions because much data already exists on "upstream emissions," or emissions from the natural gas drilling process. CAFEE hopes that its data will be a reliable source of pump-to-wheel data for other researchers and the government.
"As your start to reveal the sources of the emissions, the idea would be to address the low-hanging fruit and stop some of the emissions," Clarke said.
Clarke added that the data would allow researchers to create projections and further examine how to lower methane emissions.