Accelerated Reduction in SO2 Emissions from the U.S. Power Sector Triggered by Changing Prices of Natural Gas

Xi Lu,Gang Wu,Michael B Mcelroy,Chris P Nielsen

doi:10.1021/es301023c

Abstract

Emissions of sulfur dioxide (SO(2)) from the U.S. power sector decreased by 24% in 2009 relative to 2008. The Logarithmic Mean Divisia Index (LMDI) approach was applied to isolate the factors responsible for this decrease. It is concluded that 15% of the decrease can be attributed to the drop in demand for electricity triggered by the economic recession, and 28% can be attributed to switching of fuel from coal to gas responding to the decrease in prices for the latter. The largest factor in the decrease, close to 57%, resulted from an overall decline in emissions per unit of power generated from coal. This is attributed in part to selective idling of older, less efficient coal plants that generally do not incorporate technology for sulfur removal, and in part to continued investments by the power sector in removal equipment in response to the requirements limiting emissions imposed by the U.S. Environmental Protection Agency (U.S. EPA). The paper argues further that imposition of a modest tax on emissions of carbon would have ancillary benefits in terms of emissions of SO(2).

Highlights

Overall generation of electricity in the US decreased by 4.1% between 2008 and 2009
The results suggest that, on a national basis, changes in electricity generation, fuel mix, and SO2 emission intensities were responsible for reductions of respectively 0.28 metric tons (MT), 0.52 MT and 1.1 MT in SO2 emissions between 2008 and 2009, accounting for respectively 15%, 28% and 57% of the total reduction
The most important influence the analysis suggests, involved a significant decrease in the SO2 emission intensity from the coalfired power sector

Summary

Introduction

Carbon emissions from the power sector, which accounts for approximately 40% of total US greenhouse gas emissions, declined over the same period by an even larger factor, by 8.76 % in 2009 relative to 2008. Part of this reduction was attributed to the recession that set in during late 2008 with an important additional contribution due to a price-induced shift in the generation of electricity from coal to gas. Price induced switching from coal to gas contributed, as did the decrease in total power production. As we shall indicate in what follows, the reduction in SO2 emissions occurred despite the fact that the sulfur content of coal consumed by the power sector was higher in 2009 than in 2008

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Results

Conclusion