Researchers say energy companies have little incentive to prevent leaks
FRISCO — A team of engineers and scientists say that up to 15 billion cubic feet of natural gas, worth some $90 million, may be escaping from leaky pipes in the Boston area.
The researchers, led by atmospheric scientists at Harvard School of Engineering and Applied Sciences calculated the figure by analyzing a year’s worth of continuous methane measurements, using a high-resolution regional atmospheric transport model to calculate the amount of emissions.
Tackling the problem will require innovative policy because low prices and the way in which natural gas suppliers are regulated mean that gas companies have little economic incentive to make the necessary investments to reduce incidental losses from leakage, according to the Harvard researchers.
They summarized their key findings in a release:
- Some 2.7 percent of the gas that is brought to the Boston region never makes it to customers; it escapes into the atmosphere. That is more than twice the loss rate that government regulators and utilities estimate;
- Depending on the season, natural gas leaking from the local distribution system accounts for 60 percent to 100 percent of the region’s emissions of methane, one of the most insidious heat-trapping greenhouse gases.
The findings have implications for other regions, especially cities that, like Boston, are older and rely on natural gas for a significant and increasing portion of their energy needs.
While policymakers have focused on the production end of the natural gas supply chain–wells, off-shore drilling platforms, and processing plants–much less attention has been paid to the downstream gas delivery infrastructure.
The new study is published today in the Proceedings of the National Academy of Sciences. It suggests that intra-city distribution and end use systems may contribute more to the nation’s overall methane emissions than previously understood.
“There’s been a lot of interest in controlling methane emissions, but emissions from the distribution and use side of the natural gas system have been almost absent from the recent national policy conversation,” said Kathryn McKain, a Harvard graduate student who led the study with her adviser, Steven C. Wofsy, Abbott Lawrence Rotch Professor of Atmospheric and Environmental Science at SEAS. Wofsy is also an associate of the Harvard Forest, where one of the monitoring stations was established.
There are other possible sources of atmospheric methane, including landfills, sewage, agricultural operations, and wetlands. But, unlike commercial natural gas supplies, these sources don’t release ethane. Monitoring for trace ethane levels, therefore, allowed the researchers to pinpoint methane that was released by the natural gas delivery system. The team also compared their results to actual natural gas ethane content derived from operators of the major pipelines that serve the region.
Natural gas is dramatically “cleaner” compared to coal or oil, as measured by the amount of carbon dioxide released per unit of energy. And natural gas is now providing a higher share of the nation’s energy mix, due largely to deployment of extraction techniques such as hydraulic fracturing (fracking) that have brought prices down.
“This study helps us better understand where and how much methane is lost to the atmosphere while in transit from the well to where it’s used,” Wofsy said. “It’s important to understand these losses so that we can design policies that will help us realize the environmental benefits of natural gas versus other energy sources.”