On Methane Leaks from Pipelines in Bryan and College Station, Texas, USA

Abstract

Abstract:Methane is the second most important anthropogenically emitted greenhouse gas after carbon dioxide. Anthropogenic methane sources in the US are dominated by emissions from domestic ruminants and from fossil fuel exploration, storage and transmission. The fossil fuel source is primarily due to natural gas leaks along the production to distribution chain, and pipeline leaks in urban areas have been identified as a significant contributor. In this study, we evaluated possible leaks in three neighborhoods of a midsize Texas metropolitan region surrounding Texas A&M University through mobile measurements using a fast response, high precision methane analyzer. Neighborhoods were selected by age and land use, and each predetermined driving route was evaluated three times. Methane spikes exceeding 2.5 ppm were identified as leaks, and approximately one leak per mile of urban road was discovered. The largest leaks were found around the Texas A&M natural gas plant and in the oldest neighborhood to its north, while fewer leaks were found in a slightly younger neighborhood. No leaks were found in the youngest, less than 20-year old neighborhood suggesting that pipeline system age is a strong determinant of current and future leaks from the natural gas distribution system.

Effect of varying atmospheric conditions on methane boundary‐layer development in a free flow domain interfaced with a porous media domain

“…The effect of wind was particularly apparent, which showed a buildup of methane concentration towards the downstream end yielding a smaller concentration profile at high wind velocities. To describe this nonlinear behavior, we use a parametric power function as shown in Eqn (12).…”

“…To assess occupational safety in a working environment, we further use Eqn (12) to derive the portion of 'risk-free' area compared to the total area exposed for methane in a closed environment, The Fig. 4(a) denotes the risk-free area (C ࣘ C TLV ) with respect to exposure to methane (Eqn (14)) under the given wind velocity.…”

“…Specific estimates from leaky underground distribution pipelines remain still speculative. In fact, except for a few pipeline surveys conducted along major US urban city roads and national studies to update emission factors conducted along small segments of pipelines from randomly selected distribution utilities, no detailed accounts on methane emissions from leaky underground pipelines have been made. Notably, studies focusing on above‐ground methane boundary‐layer development under varying atmospheric conditions (e.g.…”