A Deep Dive Into New Methane Emissions Research

Planned GSEP gas pipe replacements in Massachusetts.
December 14, 2021

Methane emissions in Massachusetts are six times higher than the state’s estimates, according to research published this November by Harvard University and Boston University scientists (Sargent, M.R., Floerchinger, C., McKain, K., Budney, J., Gottlieb, E.W., Hutyra, L.R., Rudek, J., and Wofsy, S.C.). Their research also finds that methane emissions have not decreased significantly between 2015 and 2020. Why? And what does this mean? 

Methane is one of the most potent greenhouse gases. At HEET, we’ve known this for years. Our triage and transition strategy cuts the highest-emitting gas leaks, a huge source of methane emissions, while we work on a transition to safe and renewable energy (networked geothermal!). 

In Massachusetts, methane emissions come primarily from natural gas. The state has made it a priority to cut methane through the Gas Safety Enhancement Plan (GSEP), launched in 2014. GSEP attempts to address both safety and emissions by replacing old gas pipes with new ones. 

Two thousand pipes have been replaced so far, with 5,300 more to go. Based on the number and length of pipes replaced, the state Department of Environmental Protection (DEP) has estimated and reported a decrease in methane emissions. Yet direct measurements by Sargent et al. shows these emissions have not decreased. How is it possible that thousands of leaky pipes have been replaced, but methane emissions have not gone down? 

First, it is important to understand that the DEP’s reported numbers are a calculated estimate, while the scientific research by Sargent et al. is a direct measurement of methane from natural gas in the atmosphere. 

Second, and perhaps most interesting, the study confirms that methane is leaking not just from pipes in the street, but also from inside of buildings. Appliances such as meters, indoor gas pipes, gas boilers, stoves, ovens, fireplaces, dryers, and hot water heaters are all key aspects of a leaking gas system. Initial research by Gas Safety Inc. and HEET indicates that a majority of homes have micro gas leaks–and some have super-emitting leaks. We hope to study these indoor gas leaks more in the coming year. Stay tuned! 

Third, this new finding on the sources of methane is important, but does not mean replacing leaking pipes outdoors is not successfully reducing methane emissions. HEET has directly observed a reduction of leaks on new gas pipe, but has also observed increasing numbers of leaks on the remaining old pipe. In other words, our entire gas distribution system is so old (like Abraham-Lincoln-old!) that new gas leaks are popping up at a rapid rate, adding more methane emissions nearly as fast as leaks are eliminated. 

So, should we keep replacing all old gas pipes with new ones to reduce methane leaks? The short answer is no. Over the next 20 years, GSEP pipe replacements are estimated to cost over $40 billion. Adding new fossil fuel infrastructure ties us to the gas system for decades to come, even as Massachusetts mandates a move off gas to meet its 2050 net-zero climate goals. Paying for a project as large as the “Big Dig” that will soon be outdated just does not add up.

Still, as we make the transition to clean energy, we cannot let super-emitting leaks spew massive amounts of harmful emissions into the atmosphere. Instead of installing new gas infrastructure, fixing the highest-emitting gas leaks and working on renewable solutions is a more sustainable and cost-effective solution. 

We are happy to report that the Shared Action Plan, a groundbreaking joint effort between gas utilities and energy advocates, is on track to cut emissions from Massachusetts’ gas distribution pipelines in half. The plan focuses on fixing the largest 7% of gas leaks from the state’s gas distribution pipes, which emit half the methane emissions

The Shared Action Plan became state regulation in 2019 and repair of super-emitters began in 2020. As part of the plan, HEET verifies that utilities are correctly identifying super-emitters and that repairs are successful. 

Unfortunately, the timespan of the recent study by Harvard University and Boston University (2015-2020) didn’t overlap with the Shared Action Plan’s impact. By 2022, we expect to report a measurable reduction in methane emissions from gas leaks throughout Massachusetts. We are also getting ready to share this method with multiple states to encourage efficient methane reductions in distribution pipes across the country. 

As an alternative to replacing those leaky gas pipes, HEET continues advancing networked geothermal, or networked ground source heat pumps. Networked geothermal is a solution to heat and cool homes in a safe, non-emitting and affordable way–without gas. Redirecting some of the billions of dollars being spent replacing an aging gas system towards installing renewable infrastructure like networked geothermal would bring us closer to the safe and sustainable future we all need. 

Sargent et al.'s research findings support the gas system ‘triage and transition’ strategy HEET and allies have been pursuing for years and gives us more data with which to refine our approach. We hope to leverage the data from this research to ensure measurable methane reductions and drive the changes needed in our state’s emissions accounting.