Colorado State University is leading a groundbreaking field study to quantify methane emissions associated with natural gas gathering and processing.

This month, a team led by Anthony Marchese, mechanical engineering professor and new director of the CSU Engines and Energy Conversion Laboratory, will begin collecting data from potential methane sources associated with natural gas midstream facilities, between the wellhead and long-distance transmission pipelines.

Methane is a potent greenhouse gas, and natural gas and petroleum systems are the largest single source of man-made methane emissions in the United States, according to the Environmental Protection Agency.

This study will concentrate on the second stage in the natural gas supply chain - gathering and processing - where the gas is collected from the well, then compressed and processed to remove water, hydrogen sulfide, carbon dioxide and heavier hydrocarbons before entering the transmission system.

"Although some data exist on the larger processing plants, there is very little existing data on the methane emissions from other components of the gathering system," Marchese said.

"Our study will provide additional independent assessment of emissions from the gathering and processing sector of the on-shore natural gas industry, and our measurements will create the baseline for future studies."

While larger gas processing facilities are required to report methane emissions to the EPA, Marchese said that the methods used in the CSU study are intended to help ensure that other midstream emissions sources are accounted for. The research team will be taking downwind tracer gas measurements to capture the total facility level methane emissions from each measured site.

The results of this study will be linked to other studies already underway to allow an accurate, impartial, peer-reviewed and journal-published estimate of methane leakage throughout the entire natural gas supply chain.

"The companies participating in the study want to know where there are leaks in the system, because that's where they are losing their product," Marchese explained.

"Understanding this creates opportunities for the companies to improve their environmental performance and ensures they are maximizing the economics of their activity."

Carnegie Mellon University professor Allen Robinson will perform the tracer gas measurements along with Aerodyne Research. Over the next six months, measurements will be made at more than 100 different sites in 12 states.

Sponsors of the $1.9 million study include the Environmental Defense Fund (EDF); Access Midstream; Anadarko Petroleum Corp.; Hess Corp.; Southwestern Energy Co.; and Williams Partners Operating LLC. Operators are providing access to their gas facilities and equipment for tests in different regions throughout the country. While not a financial sponsor, DCP Midstream is also allowing the study team access to its sites. Hess Corp. is participating only in the development of methodologies.

In addition, participating companies will provide emissions and operating data from previous methane measurements.

"It's important that we have access not only to the gathering and processing sites, but to the operators' records to determine the conditions of the facilities as we take our measurements and compare our findings to past results," Marchese said.

The total data set, including the measurements from the CSU team, will then be used in a model to estimate methane emissions from the natural gas gathering and processing sector in the United States. Daniel Zimmerle, a senior researcher with CSU's Energy Institute, will be leading the data analysis and modeling efforts.

"The diversity of the types of gathering and processing systems in the U.S. makes the modeling and scaling process extremely challenging," Zimmerle said. "We are confident, though, that our data analysis approach will result in an accurate evaluation of methane emissions from this sector."

A panel of professors and experts in the fields relevant to the study will serve as independent advisors reviewing the appropriateness of the methodologies, the model, statistical methods, and study results.

Results are expected to be submitted for publication in summer 2014 and will help better define a national methane emissions rate for the U.S. natural gas infrastructure.

The CSU study is part of a two-year comprehensive methane research effort involving more than 90 academic, research and industry partners organized by EDF. The stated mission of the large research effort is to collect and evaluate data to more fully characterize methane emissions across the natural gas supply chain.

This is the second methane emissions study undertaken by CSU this year. Researchers from the University's Energy Institute, including Zimmerle and director Bryan Willson, are leading a study of methane emissions from natural gas transmission and storage facilities, also part of the multi-phase infrastructure study organized by EDF.