Natural gas leaks across metropolitan Boston are more serious than past studies by the industry have shown, according to the lead author of a new report.
Ph.D. candidate Margaret Hendrick of Boston University’s (BU) earth and environment department appears to provide further ammunition for climate change mitigation advocates, according to the work she oversaw in "Fugitive Methane Emissions from Leak-Prone Natural Gas Infrastructure in Urban Environments," which was published Monday in Environmental Pollution.
BU researchers said the work emphasizes the risks from fugitive gas emissions from a safety and environmental standpoint, differing from what gas companies and other monitoring groups have reported. Nearly 15% of the leaks found in the research work were characterized as potentially explosive.
Hendrick told NGI on Tuesday that the numbers of leaks found in the Boston pipes matched earlier research, but the classification of their seriousness, from both safety and climate change standpoints, are different from the past research as they were understated. Both the BU and past research used methane-measuring equipment in motor vehicles, but only in the most recent work did researchers also obtain on-the-ground data collection, she said.
"What we argue in our paper is that to truly assess the safety classifications for the leaks it requires you to get out of the vehicle to do further measurements with auxiliary monitoring equipment, such as a flame ionization unit," Hendrick said. "This better measures the accumulation of gas in manholes or buildings."
Based on data collected from 100 monitoring locations along Boston's cast iron pipeline system, researchers said that 7% of the leaks recorded accounted for one-half of the total leak volumes. Hendrick said old gas distribution systems, including cast iron, wrought iron and unprotected steel piping, have been found to be leaky, but BU documented how much the leaks vary in size in large urban areas such as Boston.
In recent years, studies in Boston and elsewhere have noted the need to replace cast iron pipe and other outdated technology, and when there is a concerted effort in leak detection, methane emission levels have dropped (see Daily GPI, Sept. 23, 2015; Nov. 26, 2012).
BU's research is the first survey that carried out detailed measurements of gas losses from pipelines on an urban scale, according to BU professor Nathan Phillips.
"We know we have a problem with aging natural gas infrastructure, but we need a better understanding of how big the problem is and the best ways to solve it," Hendrick said. "We are consuming more natural gas than ever before in the United States. We need research to try to characterize fugitive methane emissions across the entire natural gas system."
The Environmental Defense Fund (EDF) and several industry and university partners have been studying leaks from various parts of gas infrastructure for years, including in the Boston area (see Daily GPI, Feb. 24; May 15, 2015; July 16, 2014). EDF has campaigned for more systematic work on detecting and limiting leaks, arguing that the estimated volumes of methane emissions have been under-reported, and the Energy Information Administration has tracked methane leaks as well (see Daily GPI, Jan. 12).
Hendrick emphasized that the research found that "even small leaks can be very hazardous, and we wanted to make the point that it is not just the very large leaks that are posing a threat to our safety." Environmental risks of climate change may be addressed by fixing the super leaks, but for safety concerns, all leaks need to be addressed. "That's why we need a two-fold approach where we address all gas leaks, not just a few."
The BU report recommended a two-pronged leak classification methodology that addresses safety and climate change risks inherent in any leak. Ultimately, the researchers want more stringent rules to detect and fix leaks across the gas infrastructure system. “All leaks must be addressed as even small leaks cannot be disregarded.”
The study cited the recently concluded four-month-long gas storage well leak in Southern California as underscoring the importance of addressing the issue (see Daily GPI,Feb. 18).
Among other things, Phillips worked with Gas Safety USA’s Bob Ackley in a methane-detection-equipped vehicle to conduct ground measurements in and along Boston roadways. The pair in January conducted similar testing in Southern California during the Aliso Canyon storage well leak to determine the presence of elevated methane levels.
Methane, the primary constituent of natural gas, accounts for 10% of all U.S. greenhouse gas (GHG) emissions, about 30% of which are attributable to natural gas and petroleum systems, according to U.S. Environmental Protection Agency data.