Quantifying Upstream Emissions From Natural Gas Production In Northeastern Pennsylvania
Open Access
- Author:
- Barkley, Zachary Robert
- Graduate Program:
- Meteorology
- Degree:
- Master of Science
- Document Type:
- Master Thesis
- Date of Defense:
- June 27, 2016
- Committee Members:
- Thomas Claude Yves Lauvaux, Thesis Advisor/Co-Advisor
Kenneth James Davis, Committee Member
Chris E. Forest, Committee Member - Keywords:
- Natural gas
Methane
Aircraft mass balance
CH4
Emission rate
Marcellus
fugitive emissions
Climate
Climate Change
Methane inventory - Abstract:
- Leaks in natural gas infrastructure release methane, a potent greenhouse gas, into the atmosphere. The estimated emission rate associated with the production and transportation of natural gas is uncertain, hindering our understanding of the fuel source’s greenhouse footprint. This study presents a new application of inverse methodology for estimating regional emission rates from natural gas production and gathering facilities in northeastern Pennsylvania. An inventory of methane emissions was compiled for major sources in Pennsylvania. This inventory served as input data to the Weather Research and Forecasting model with chemistry enabled and atmospheric methane mole fraction fields were generated at 3km resolution. Projected atmospheric methane enhancements from WRF-Chem were compared to observations obtained from a three-week flight campaign in May 2015. Model projected enhancements from sources not associated with upstream natural gas processes were removed from the observations, creating a set of observed enhancements from natural gas. Emission rates within the model from unconventional production were then adjusted in the model to minimize errors between aircraft observations and the model-simulated concentrations for each flight, and an optimal emission rate is estimated. As an additional method for calculating emission rates, a simplified aircraft mass balance calculation was performed for four flights. The weighted mean emission rate from natural gas production and gathering facilities in northeastern Pennsylvania using the model optimization approach is found to be 0.36% of total gas production, with a 2σ confidence interval between 0.27-0.45% of production. Similarly, the mean emission estimates using the aircraft mass balance approach is calculated to be 0.35% of regional natural gas production, with a 2σ interval between 0.21-0.49% of production. These emission rates are lower than rates found in any other basin using a top-down methodology, and may be indicative of some characteristic which makes emission sources from the Marcellus natural gas industry unique.