This page presents the first annual report card for the performance of coal-fired power plants across the eastern United States. The Report card covers coal-fired Electricity Generating Units (EGUs) that have installed advanced nitrogen oxide (NO_x) pollution control technologies. Many of these EGUs have already spent billions of dollars on advanced technology to control NO_x, yet they do not always use the technology effectively. This is especially important during the summer months when NO_x can combine with sunlight and heat to form ground-level ozone or smog. Research shows that ozone is often transported - by westerly and southerly winds - into the northeast from upwind states at levels that are already approaching the 70 parts per billion ozone standard.

The report card covers 323 coal-fired EGUs that have already installed advanced NO_x control technology. The report card focuses on EGUs in the eastern U.S. and is based on the actual emissions reported by sources to the EPA's Clean Air Markets Division (CAMD).

MDE's analysis demonstrates that by running pollution controls effectively throughout the 2017 ozone season (May-September) up to 400 tons of NO_x emissions per day could have been reduced. This equates to over 46,000 tons of NO_x emissions reductions that could have been reduced over the 153-day ozone season. The data for this analysis is available by clicking here. The report is available here.

The methodology to distribute letter grades to individual EGUs builds from Maryland's 2017 ozone season analysis of control optimization at coal-fired EGUs with Selective Catalytic Reduction (SCR) and Selective Non-Catalytic Reduction (SNCR) controls across the eastern United States. MDE developed a grading system based on individual EGU performance rates.

A deviation percentage was then calculated for each unit by dividing the current ozone season average emission rate by the identified best ozone season average emission rate. Units were then subdivided into three categories, or bins, based on the calculated percent deviation. Each of these bins represents a different level of optimization based on the unit's own previously demonstrated performance. 

Table 1. Description of Three Bins for EGU Optimization Performance

Grading Scale

While MDE's binning methodology allows comparison of a unit's control performance in a particular year to its own previously demonstrated capabilities, it does not allow comparison of units to each other. In order to assign a letter grade to each unit, MDE used the binning methodology in conjunction with performance rates for SCR and SNCR technologies to provide an indication of the unit's overall efforts to optimize controls. The following charts illustrate the methodologies used for grading EGU units. The methodologies are identical, but with different rate performance standards for SCR and SNCR units. Under this methodology, any SCR unit that achieved a 2017 rate less than 0.10 lb/mmBtu and any SNCR unit under 0.15 lb/mmBtu would receive a grade of A or A+ depending on their designated bin.