Pollution Externalities and Emissions’ Consequences of the U.S. Electricity Sector
Creators: name: Xiaodi Sun
Publisher: name: Carnegie Mellon University
Year: 2019
Subjects: subject: 160510 Public Policy
subject: FOS: Political science
subject: FOS: Political science

description: The electricity sector generates externalities due to pollution that can have damaging impacts on human health, environment, ecology, and climate. This thesis focuses on three problems related to health, environmental and/or climate change externalities associated with the operation of the power sector. In Chapter 1, I estimate the trace elements mass flow rates from U.S. coal-fired power plants, a negative externality that is not well monitored at the plant level, except for gas phase emissions of Hg. I create a generalizable model for stochastically estimating trace element mass flow rates, specifically Hg, Se, As, and Cl, to solid, liquid, and gas phase waste streams of coal-fired power plants and evaluate the accuracy against available data. When compared with measured and reported data on trace element mass flow rates, I find that my model generally overestimates trace element concentrations in coal, leading to overestimation of trace element mass flow rates to the waste streams. The partitioning estimates are consistent for Se, As, and Cl removal from flue gas, but tend to underestimate Hg removal. Model performance would improve with access to more recent measurements of trace element concentrations in the coal blend, where data quality is the weakest. In Chapter 2, I focus on the issue of understanding the emissions of SO<sub>2</sub>, NO<sub>x</sub> and CO<sub>2</sub> that would result from policies that would lead to an increased usage of coal. I also study the emissions consequences of turning off some of the currently installed air pollution technologies at U.S. coal power plants. While a coal resurgence is unlikely due to other market forces, an increase in coal electricity will cause increases in SO<sub>2</sub>, NO<sub>x</sub> and CO<sub>2</sub>, which have significant human health, environment, and climate consequences. I explore the potential consequences of an increase in coal generation under two bounding scenarios: 1) I assume that environmental regulations are weakened so that coal plants turn off their wet flue gas desulfurization and selective catalytic reduction devices and 2) I assume coal electricity becomes cheaper to operate than natural gas and displaces natural gas electricity. Turning off wet flue gas desulfurization and selective catalytic reactor devices leads to SO2 and NOx that would be twice to three times the emissions observed in 2017. These emissions levels were last observed about 7-10 years ago. A resurgence of coal that would displace natural gas would increase SO<sub>2</sub>, NO<sub>x</sub>, and CO<sub>2</sub> emissions by 41%, 45%, and 21% compared to 2017 levels. In Chapter 3, I study the potential of deep decarbonization of the Pennsylvania electricity sector, which is an energy policy goal which would push coal out of the fuel mix. The Pennsylvania Department of Environmental Protection aims to reduce greenhouse gas emissions from Pennsylvania to 20% of 2005 levels by 2050. While deep decarbonization is crucial for mitigating the effects of climate change, the infrastructure required to implement deep decarbonization can create significant land and forest impacts that may negatively impact ecology. I model pathways to deep decarbonize Pennsylvania’s electricity sector, quantify the land and forest land use from these pathways, and estimate potential ecological impacts using fragmentation indices. Even if all the coal plants retire, the emissions from current natural gas plants exceed the carbonization goals, suggesting that natural gas cannot be a bridge fuel. If only wind is built, the total land use is 13,300 km<sup>2</sup> (Pennsylvania is 119,000 km<sup>2</sup>), with direct land use and forest land use impacts of 520 km<sup>2</sup> and 370 km<sup>2</sup>, respectively. Solar farms are constructed across Pennsylvania, as there is insufficient land in the southeast where resources are highest, impacting 2400 km<sup>2</sup> of forested land. As such, solar contributes to a greater loss of landscape than wind, but wind requires significantly more land allocated to deep decarbonize the Pennsylvania electricity sector. Through these three chapters, I find that energy policy needs to be assessed on a holistic basis by considering all possible cost and benefits of a potential policy. While policy goals, such as decarbonization of the electricity grid, will create obvious net benefits, energy interventions still need to be carefully planned out by decision makers to avoid and minimize other downstream problems. Other policy interventions, such as promoting more coal for the sake of grid reliability, may introduce such significant costs that they should be scrapped entirely.<br>