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Quarterly SO2 Emissions Tracking

Motion chart graphic of United StatesEPA regularly posts updates of quarterly sulfur dioxide (SO2) emissions data from coal-fired power plants subject to the Acid Rain Program to make it easy for the public to track changes in emissions from these sources.

Since the D.C. Circuit Court decision to vacate the Clean Air Interstate Rule (CAIR) in late 2008, allowance prices of SO2 have been relatively low. This has raised concerns that coal-fired units could “backslide” on emission reductions. For example, units could burn dirtier fuels, operate scrubbers at reduced efficiency, or even bypass scrubbers altogether, relying instead on banked allowances. EPA is tracking SO2 emissions closely each quarter to evaluate further progress and assess whether backsliding may be occurring and, if so, where it may be taking place.

EPA will add new data to this website on a quarterly basis as it becomes available. For additional information and a detailed description of the analyses presented here, please see the background section of this site.

Coal-fired Power Plant Emission Data: 2008 vs. 2009 (Second and Third Quarters)

The data presented here compare emissions, emission rates, and heat input from power plant units in the Acid Rain Program. These files graphically and spatially compare second and third quarter emission data from 2009 (April - June, July-September) with second and third quarter data from 2008.

The data show that while a few facilities are emitting more SO2 or emitting SO2 at a greater rate than last year, overall emissions are still declining substantially.

Questions

What is Heat Input?

Heat input, often expressed in million British thermal units (mmBtu), is a measure of the energy content of fuel. It is standardized across fuel sources to allow comparisons among them. For example, a cubic foot of natural gas releases a different amount of energy than a gallon of oil when burned. Heat input also offers an indication of energy demand. For example, high electricity consumption for air conditioning on a hot day will be reflected in high heat input levels at EGUs.

What is Emission Rate?

Emission rate is the measure of how much pollutant (SO2) is emitted from a combustion unit compared to the amount of energy (heat input) used. Emission rate is expressed as pounds of SO2 emitted per mmBtu of heat input. Emission rates enable comparison of a combustion unit's environmental efficiency given its fuel type and usage. A lower emission rate represents a cleaner operating unit—one that is emitting fewer pounds of SO2 per unit of fuel consumed.

SO2 emissions from 2000-2014

Changes in Control Technologies at Coal-Fired Units: 2000-2014

The following figures display where particular control technologies have been installed between 2000 to 2008 as well as what technologies EPA anticipates will be installed in 2010, 2012, and 2014 based on the information obtained from major company contacts and industry sources.

The data show that more and more coal-fired units are installing advanced controls, such as scrubbers, which are dramatically reducing pollution across the country.

Interactive Motion Charts Showing Changes in Emissions and Emission Rates

The following interactive motion charts show changes in emissions and emission rates over time and show, historically, how coal-fired power plants have responded to the Acid Rain Program.

The data show that air pollution was reduced even as electricity generation increased.

Video tutorials of interactive motion charts

Intorductory video

Introduction to chart features

 

 

 

Technical background on SO2 emissions data

 

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