Boston’s natural gas pipeline infrastructure is showing the signs of age, and is starting to leak like a sieve, according to a group of atmospheric scientists at Harvard School of Engineering and Applied Sciences (SEAS).
Not only are these methane leaks pouring more carbon dioxide into an atmosphere already responsible for severe climate changes, the lost gas is worth almost $90 million.
According to a news report released last week, the team estimates that each year about 15 billion cubic feet of natural gas is leaking from the Boston region’s delivery system. This figure was calculated using sophisticated air monitoring equipment in four locations; two atop buildings in the heart of Boston, and two at upwind locations well outside of the city. Then they analyzed a year’s worth of continuous methane measurements, used a high-resolution regional atmospheric transport model to calculate the amount of emissions, and concluded that:
- Some 2.7% 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 news release provided this sobering perspective:
“Imagine if every time you filled your car with gas, a few gallons didn’t make it into the tank and instead spilled onto the ground. That’s essentially what happens every day with the aging system of underground pipes and tanks that delivers natural gas to Boston-area households and businesses, with adverse economic, public health, and environmental consequences.”
Unfortunately, it appears these Boston findings may also pertain to other cities relying on natural gas to meet growing energy demand.
The new study was published in the Proceedings of the National Academy of Sciences (PNAS). 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.
Reported leaks from the Boston natural gas distribution system were also reported by CleanTechnica in 2012 by James Ayre.
It is apparent there are other possible sources of atmospheric methane, including landfills, sewage, agricultural operations, and wetlands. However, according to the Harvard team, unlike commercial natural gas supplies, sources such as these do not release methane. 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.
“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 in the press announcement. “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.”
Map image via Kathryn McKain, Harvard SEAS