NYSEARCH Project M2019-002: Standardization Of Surface Expression (SE) Measurements For Methane Emissions Validation

Fig. 1: Methane emission measurement by flux chamber surface expression along road curbing

Fig 2: Methane emission measurement by flux chamber surface expression capture

Fig 3: Methane emission measurement by flux chamber surface expression road way barhole

With increasing environmental regulatory emphasis being placed on natural gas local distribution companies (LDC) and with respect to the measurement and quantification of methane emissions, the NYSEARCH consortium has invested considerable resources into independent studies of emission quantification techniques revealing each technique’s actual performance capability. One such method which resulted in a deeper investigation for the consortium is the Surface Expression method. This multi-year effort to research and field test methods resulted in optimization of a stationary measurement tool, a recommended system with Bill of Materials, and acquisition of data that validated the methane emissions measurement process.

NYSEARCH’s objectives included improving on and standardize the Surface Expression measurement technique for use in measuring natural gas pipeline emissions. The first objective has been met and the second objective is being planned in a follow-on effort. The successful development of an improved and more compact surface expression technique has provided an effective measurement tool for gas companies to use with internal and/or contract crews. Quantification measurements that use the surface expression technique provide high accuracy and exceed any other techniques available today. Industry and environmental measurement experts can now use this data to aid collective discussions on the sources of and the uncertainties associated with LDC leaks that contribute to greenhouse gas emissions.


For more than thirty years, NYSEARCH has worked as a consortium of natural gas Local Distribution Companies (LDCs) who have a common interest and need for research and technology development and demonstration. Today, as part of the Northeast Gas Association (NGA), NYSEARCH manages over (30) projects in various stages of development for LDCs, transmission companies, federal agencies and their manufacturing and commercial partners. NYSEARCH is located in Parsippany, NJ and NGA is headquartered in Needham, Massachusetts.