Important news in the natural gas utility world last week with the release of a study published in the journal, Environmental Science and Technology, detailing a dramatic decrease in methane emissions from US local distribution systems when compared to prior estimates.
The study was led by the Northwest’s own Washington State University, with the support of the Environmental Defense Fund (EDF), Conestoga-Rovers and Associates, an engineering and environmental consulting firm, and major natural gas utilities from across the US.
Check out the video below for a review of study’s justification and methodology:
Three key takeaways from the study (you can access the entire study by clicking here):
- Methane emissions from local distribution systems are estimated to be 36-70 percent lower than EPA estimates:
“The researchers found that upgrades in metering and regulating stations, changes in pipeline materials, better instruments for detecting pipeline leaks as well as regulatory changes have led to methane emissions that are from 36% to 70% lower than current Environmental Protection Agency estimates when the data gathered for this study is combined with current pipeline miles and the numbers of facilities.”
- When returning to sites identified as large methane emitters in a study performed by the Gas Research Institute (GRI) in 1992, the researchers found significant emissions reductions in facilities that had been upgraded or replaced with newer equipment:
“To understand the large reductions found in this work relative to the GRI/EPA results, we identified nine facilities from among the larger emitting sites measured during the GRI/ EPA 1992 program to resample with our high-flow and tracer- ratio techniques. These results show substantial reductions in emissions from each individual station (factors of 2 to 50) from 1992 to the present, with one exception. In two cases, the local operator indicated that significant equipment changes had occurred at the site; while at a third site, the local operator indicated that there had been no equipment upgrades at the site in the past 20 years. This particular site was the only site without a significant reduction in emissions.”
- While emissions nationwide were lower than prior estimates, utilities located in the Western US were responsible for emissions rates even lower than the national average:
“We also examined how emissions from pipeline leaks varied on a regional basis in the U.S. due to differences in pipeline type and miles by region (see SI Section S4.3; there was no statistical difference in EFs by region). The eastern region accounts for 34% of the total U.S. CH4 from pipeline leaks, while the western region contributes less than 20% (Figure 1). In the eastern region, emissions are dominated by leaks from cast iron and unprotected steel characteristic of older systems. As such, leaks from cast iron and unprotected steel pipe account for 70% of the eastern emissions and almost half of total U.S. emissions. In the western region, systems are newer with more miles of plastic and protected steel pipe, and leaks from these systems contribute less than 5% of the total U.S. emissions. These regional variations and the low emissions associated with plastic pipes are significant as the U.S. moves toward replacement of older pipelines with plastic and uses plastic for new distribution expansion.”
This study was the third in a series reviewing methane emissions from throughout the natural gas supply chain. In each case the research was performed with the cooperation of the EDF, an academic institution, and relevant natural gas facility owners and operators.
Stay tuned for a blog in the coming weeks where we’ll discuss some of the parallels between each of the three studies.