Cumulative Impact and Equity Objectives in Energy Systems Modeling and Policy

2019-03-06T18:22:23Z (GMT) by Erin Mayfield
<div>Energy system development is driven by the complexity inherent in physical systems and the influence of a myriad of diverse, interacting stakeholders with heterogeneous preferences. Transforming energy systems entails balancing multiple and often conflicting societal objectives. This thesis presents new modeling approaches for energy systems planning and policy evaluation, with an emphasis on cumulative impacts, equity, and system heterogeneity. The application domain of this thesis is the U.S. natural gas system, although the analytical approaches and insight of this research are intended to extend to the broader domestic and global energy system.</div><div><br></div><div>Chapter 2 adopts a traditional economic efficiency optimization approach, coupled with methane emissions and abatement cost simulations reflecting system heterogeneity, to evaluate and design system-wide and super emitter policies related to methane abatement in the U.S. transmission and storage system. We find that most emissions, given the existing suite of technologies, have the potential to be abated. We also demonstrate that there are high societal benefits from abatement policies, and minimal (if any) private costs under standard and tax instruments. Superemitter policies, which target the highest emitting facilities, may reduce the private cost burden and achieve high emission reductions, especially if emissions across facilities are highly skewed. However, detection across all facilities is necessary regardless of the policy option, and there are nontrivial societal benefits resulting from abatement of relatively low-emitting sources. </div><div><br></div><div>Chapters 3 aims to develop and demonstrate a data-driven approach for characterizing systems-level cumulative impacts of current energy systems. Specifically, we comprehensively assess the spatially-and temporally-resolved air, climate, and employment impacts from extraction to end use and over the life of natural gas plays in the Appalachian basin from 2004 to 2016. Our approach highlights the attribution of impacts across the supply chain, the tradeoffs between near- and long-term impacts, and the evolution and accumulation of impacts over time with changing regulation, natural gas activity, and technological and operational efficiencies and practices. We show that short-lived air quality and employment impacts track with the boom-and-bust cycle, while climate impacts persist for generations well beyond the period of natural gas activity. We also find that employment effects are spatially concentrated in rural areas with thin labor markets where development is occurring, and more than half of cumulative premature mortality is within source emissions states. We show that most premature mortality is associated with end uses, while upstream and midstream segments also account for a substantial portion of impacts. With respect to climate</div><div>change impacts, the magnitude of methane emissions across the supply chain produces temperature impacts nearly equivalent to that of carbon dioxide over a 30-year time horizon, but over longer integration periods, the warming impact from carbon dioxide dominates. We estimate a tax on production of $2 per thousand cubic foot (+172%/-76%) would compensate for cumulative climate and air quality externalities across the supply chain.</div><div><br></div><div>In Chapter 4, we develop a multiobjective optimization model incorporating cumulative impact objectives to facilitate future energy system planning. We develop natural gas system pathways by optimizing impacts with respect to sequential natural gas decisions regarding the timing and location of infrastructure and activity from extraction to end use. Environmental and employment objectives are conflicting if we follow a natural gas pathway consistent with the status quo; however, a collection siting, emissions abatement, and renewable integration policies may collectively resolve and reverse these conflicts.</div><div><br></div><div>In Chapter 5, we develop and demonstrate an approach for evaluating the equity state of an energy system. We apply variants of standard methods and present new methods and metrics to quantify spatial, temporal, and distributional equity, leveraging impact estimates of the shale gas boom in the Appalachian basin from Chapter 3. We find that there are high temporal and spatial inequities with respect to cumulative air and employment impacts, and that spatial inequities are constant over time reflecting largely fixed infrastructure and consumption patterns. We also present indicators of temporal climate inequities, estimating that long-term global temperature impacts are 100 times that of near-term impacts. With respect to distributional equity of air quality impacts, we do not observe a disparity in mortality rates across sub-populations on the basis of income and poverty; however, there is a trend of increasing income corresponding to decreasing damages, which demonstrates the higher health burden of lower income communities. With respect to distributional equity of labor markets, we find statistically significant declines in the income disparity and poverty rates in producing counties. Pairwise comparisons of impacts reveal that changes in air and climate impacts are sensitive to changes in employment impacts.</div><div><br></div><div>In Chapter 6, we develop future natural gas system pathways that optimize for the multiple dimensions of equity. We expand upon the multiobjective optimization model developed in Chapter 4, deriving objectives that instill different normative concepts of spatial, temporal, and distributional equity that apply to air, climate, and employment impacts. We find that there are inherent conflicts between different equity dimensions, as well as, between equity and cumulative impact objectives in a fossil-fuel dominated energy system. However, low-carbon technologies have the potential to reduce inequities. </div>