Reducing Nitrogen Oxide Emissions: 1996 Compliance with Title IV Limits
May 1, 1998
Introduction
A variety of Federal and State regulatory initiatives are aimed at reducing nitrogen oxide (NOx) emissions from electricity generators. NOxemissions are a concern because they contribute to the formation of acid rain and, either directly or through the creation of ozone, lead to harmful effects on human health. It has been determined that the combustion of fossil fuels is the major source of NOxemissions. According to estimates made by the U.S. Environmental Protection Agency (EPA), highway vehicles accounted for 35 percent of the 22 million tons of NOxemissions in the United States in 1995, and electric utilities accounted for 29 percent.
To address this issue, electric utilities began complying in 1996 with the first phase of the acid deposition control regulations established by the EPA under Title IV of the Clean Air Act Amendments of 1990 (CAAA90). This first phase places limits on NOxemissions from 239 older coal-fired generating units. Overall, the utilities that operate the affected units achieved a 40-percent reduction in the emissions rates of the units and a total reduction of approximately 340,000 tons of NOxemissions in 1996 from their 1990 levels. In most cases, the units were retrofitted with low-NOxburners that control fuel and air mixing to limit NOxformation.
The purpose of this article is to summarize the existing Federal NOxregulations and the 1996 performance of the 239 Title IV generating units. It also reviews the basics of low-NOxburner technology and presents cost and performance data for retrofits at Title IV units.