Colorado State University

Mid-Continent Methane Emission Estimates ľA Collaborative Study for the Department of Energy

RPSEA Study Team RPSEA Sponsors RPSEA Committees

 

Project Overview:

In this first-of-its-kind Mid-Continent Methane Emissions Study, researchers from across the region, universities, government agencies, and industries joined forces determined to reconcile longstanding discrepancies between measurement methods in methane loss rates from onshore oil and gas developments in multiple basins. Seeking to bring public and private sectors better understanding of this issue, the combined resources of these groups resulted in weeks of field study and conclusive data. This team discovered that in previous studies, top-down measurements reported much higher methane leak rates than bottom-up methods. Equipped with that knowledge, this team used paired measurements from the same natural gas sources to determine the inconsistencies in measurement methods. The result of a field campaign, which happened over a five-week period from late September to early October 2015 is described in the study overview below.

 

 

Research Outcomes Reconciling Top-down and Bottom-up Methane Emission Estimates from Onshore Oil and Gas Development in Multiple Basins

(Funding for this work was initially provided by RPSEA/NETL contract no 12122-95/DE-AC26-07NT42677 to the Colorado School of Mines with full acknowledgement of this funding that attracted additional industry and Govt. cost share is noted in Sponsors section).

 

Objectives

This study was designed to develop independent estimates of methane emissions using top-down and bottom-up measurement approaches and then to compare the estimates, factoring in necessary consideration of uncertainty. These approaches were applied at two stages: (1) basin and (2) facility. On the facility scale, multiple methods were used to measure methane emissions of the whole facility – such as controlled dual tracer and single tracer releases, aircraft-based mass balance and Gaussian back-trajectory – which are considered top-down approaches. The bottom-up approach consisted of emissions from identified point sources – measured using appropriate source-level measurement techniques (e.g., high-flow meters). On the basin scale, the top-down estimate came from boundary layer airborne measurements upwind and downwind of the basin, using a regional mass balance model plus approaches to separate atmospheric methane emissions attributed to the oil and gas sector. The bottom-up estimate resulted from statistical modeling – also known as scaling up – of measurements made at selected facilities, with gaps filled through measurements and other estimates based on other related studies. The relative comparison of the bottom-up and top-down estimates made at both scales were used to help improve understanding of the accuracy of the tested measurement and modeling approaches.

 

This study addressed several additional scientific questions:

Energy Institute Member Organizations

Center for Energy and Behavior Center for Energy Development and Health Center for Energy Water Sustainability Center for Laser Sensing and Diagnostics Center for Next Generation Photovoltaics Center for the New Energy Economy Electric Power Systems Laboratory Engines and Energy Conversion Laboratory Industrial Assessment Center Institute for the Built Environment Rural Energy Center Sustainable Biofuels Development Center