Observations of Methane Emissions from Natural Gas-Fired Power Plants.
Kristian D Hajny, Olivia E Salmon, Joseph Rudek, David R Lyon, Andrew A Stuff, Brian H Stirm, Robert Kaeser, Cody R Floerchinger, Stephen Conley, Mackenzie L Smith, Paul B Shepson
Author Information
Kristian D Hajny: Purdue University , Department of Chemistry , West Lafayette , Indiana 47907 , United States. ORCID
Olivia E Salmon: Purdue University , Department of Chemistry , West Lafayette , Indiana 47907 , United States.
Joseph Rudek: Environmental Defense Fund , Austin , Texas 78701 , United States.
David R Lyon: Environmental Defense Fund , Austin , Texas 78701 , United States.
Andrew A Stuff: Purdue University , Department of Chemistry , West Lafayette , Indiana 47907 , United States.
Brian H Stirm: Purdue University , School of Aviation and Transportation Technology , West Lafayette , Indiana 47906 , United States.
Robert Kaeser: Purdue University , Department of Chemistry , West Lafayette , Indiana 47907 , United States.
Cody R Floerchinger: Harvard University , Department of Earth and Planetary Sciences , Cambridge , Massachusetts 02138 , United States.
Stephen Conley: Scientific Aviation, Inc. , Boulder , Colorado 80301 , United States. ORCID
Mackenzie L Smith: Scientific Aviation, Inc. , Boulder , Colorado 80301 , United States.
Paul B Shepson: Purdue University , Department of Chemistry , West Lafayette , Indiana 47907 , United States.
Current research efforts on the atmospheric impacts of natural gas (NG) have focused heavily on the production, storage/transmission, and processing sectors, with less attention paid to the distribution and end use sectors. This work discusses 23 flights at 14 natural gas-fired power plants (NGPPs) using an aircraft-based mass balance technique and methane/carbon dioxide enhancement ratios (ΔCH/ΔCO) measured from stack plumes to quantify the unburned fuel. By comparing the ΔCH/ΔCO ratio measured in stack plumes to that measured downwind, we determined that, within uncertainty of the measurement, all observed CH emissions were stack-based, that is, uncombusted NG from the stack rather than fugitive sources. Measured CH emission rates (ER) ranged from 8 (±5) to 135 (±27) kg CH/h (±1σ), with the fractional CH throughput lost (loss rate) ranging from -0.039% (±0.076%) to 0.204% (±0.054%). We attribute negative values to partial combustion of ambient CH in the power plant. The average calculated emission factor (EF) of 5.4 (+10/-5.4) g CH/million British thermal units (MMBTU) is within uncertainty of the Environmental Protection Agency (EPA) EFs. However, one facility measured during startup exhibited substantially larger stack emissions with an EF of 440 (+660/-440) g CH/MMBTU and a loss rate of 2.5% (+3.8/-2.5%).
