Gas Technology Institute (GTI), with project partners AECOM, GHD Services, Inc., and Washington State University will improve the characterization of methane emissions from the natural gas distribution system. The project will focus on emissions from industrial meters in the natural gas distribution system, differences between vintage and new plastic pipelines, and gather data to compare steel and cast iron pipelines with and without plastic liners. The project team will conduct an unprecedented assembly of existing and new field data on methane leaks that will feed advanced statistical methods to offer a new perspective on methane emissions, the metrics/categories used to estimate emissions, and techniques used to curb those emissions.
Gas Technology Institute, Des Plaines, IL 60018
To meet the Nation’s Climate Action Plan goal of reducing emissions 40–45% below 2012 levels by 2025 requires a comprehensive understanding of the emissions profile from the entire natural gas infrastructure to enable cost-effective and efficient identification and control of methane emissions. This project will contribute to one piece of the research needed to provide input into a cohesive strategy for greenhouse gas reduction. The EPA Greenhouse Gas Inventory (GHGI) estimates are used to drive environmental policy and regulations at the federal level, which directly impacts individual natural gas customers, rate payers. By reducing uncertainty and improving the characterization of methane emissions from the gas industry, appropriate regulations will be made, the cost of compliance will be reduced, and the savings will be passed on to the rate payers.
The research will have a significant impact on the national estimates of methane emissions from the natural gas industry. It is intended that the improved Emissions Factors and activity data will be incorporated into EPA’s annual GHGI. The proposed project will also identify specific metrics to be tracked at a company level so operators can prioritize the repair of their non-hazardous leaks to maximize the reduction of methane emissions. Studies have shown fat-tailed emissions can be responsible for up to 50% of total emissions. By identifying these leaks, operators can more efficiently reduce the environmental impacts of their system. The results from the study will also improve the activity data estimates for specific sources such as industrial meters and distribution pipelines. This can help individual companies develop targeted leak repair programs for non-hazardous leaks to optimize emissions reductions. Specifically, the data collected on emissions from cast iron and unprotected steel with plastic liners will help determine if this is an effective practice for reducing leaks. It could then be made into practice in the field and possibly support the creation of a different classification for this type of pipeline to promote the use of these liners as a method of reducing emissions. A reduction in leaks also improves safety for customers and the public.
GTI has wrapped up the extensive field data collection section of the project. At this point, GTI has completed all 10 planned weeks of industrial meter measurements in all 6 regions nationally along with 3 weeks of revisiting already sampled meters. Overall, GTI has visited over 400 individual industrial meter sets and revisited approximately 100, conducting detailed leak surveys and component counts. During seven of the sampling weeks, GTI focused on maximizing the number of sites visited, only quantifying leaks that indicated 45% LEL concentration or higher. For three of the sampling weeks, GTI quantified every leak that presented at 100 ppm or higher to better understand all leaks coming from this category. Distribution of the data for industrial/commercial meters sampled followed a strong, “fat-tailed” distribution with 80% of fugitive methane emissions coming from 10% of the leaks. This was also true within individual meter types (rotary, diaphragm, turbine). Data has been organized and advanced statistical analysis has begun.
Additionally, GTI has completed all 10 weeks of measurements of new vs. vintage plastic pipe in 5 of 6 regions nationally which includes visiting 270+ sites and quantifying 170+ individual leaks. Verification of pipe material type — to be certain the leaks are correctly categorized — has been completed for two utility partners, and GTI is currently waiting on verification from the other industry participants.
GTI conducted one field campaign to survey 10,031 ft of cast iron and steel mains lined with cured-in-place-plastic liners and did not locate any leaks on the specific segments of plastic lined pipe. The lack of leaks on these segments, coupled with few or no leaks in partner companies records of leaks on these types of pipe, has caused GTI (with the approval of DOE) to shift focus away from these types of pipe for this project.
Finally, GTI has finished organizing the data and begun both basic and advanced statistical analyses of the data..