The environmental and political ecology of natural gas
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Methane (CH4) is the primary constituent of natural gas and a significant contributor to global climate change, accounting for 11% of all U.S. greenhouse gas emissions. With the advent of hydraulic fracturing technology, production of natural gas from shale gas reserves has increased by 35% from 2005 to 2013. Fugitive CH4 emissions attributed to venting or leakage across the life cycle of natural gas systems have also increased, making the climate benefits ascribed to natural gas questionable when compared to oil and coal. This dissertation reports the results of three studies that improve our knowledge of the environmental and political ramifications of continued investment in and consumption of natural gas fuels. Using bottom-up flux chamber techniques we made direct measurements of CH4 emissions from 100 natural gas leaks in cast iron distribution mains within Metro Boston, MA in order to assess the nature of the distribution of gas leak size and constrain estimates of fugitive CH4 emissions across leak-prone urban distribution infrastructure. We find that the distribution of leak size is skewed, a small fraction of ‘superemitter’ leaks contribute disproportionate CH4 emissions, and CH4 flux at leak sites is not an indicator of safety. Next, we use the lens of urban natural gas infrastructure systems and apply an ecological analytical framework to identify dysfunctions in and opportunities for coordinated urban infrastructure management in Boston, MA. We find that there are real physical and fiscal constraints to retrofitting and expanding aging, urban infrastructure in U.S. cities. Achieving sustainable, resilient urban infrastructure requires active participation by all stakeholders as well as coordination within and between stakeholder groups. Finally, we introduce the term ‘unleakable carbon’ to refer to the uncombusted carbon-based gases associated with fossil fuel systems and demonstrate that in particular the unleakable carbon associated with natural gas constitutes a potentially large and heretofore unrecognized factor in estimating usable portions of Earth’s fossil fuel reserves. We demonstrate that unless unleakable carbon is curtailed, roughly 80 – 100% of our global natural gas reserves must remain underground if we hope to limit warming to 2 °C from 2010 to 2050.