Comanche Station Air Emissions

Overview

Xcel Energy entered into a comprehensive, ground-breaking settlement agreement with many environmental and community organizations concerning our 2004 Colorado least-cost resource plan and the construction of a new unit at Comanche Station in Pueblo. We believe the environmental settlement agreement (44K PDF)  results in a better project for our customers and the Pueblo community, valuable partnerships, environmental benefits and greater information sharing.

It is with this goal in mind that we are providing emissions information concerning Comanche Station on xcelenergy.com. At our settlement agreement partners’ request, we are posting publicly reported Comanche Station emissions information quarterly so it can be accessed more easily and in a more timely manner than is currently available through the Environmental Protection Agency’s web site.

Today, Comanche Station operates two coal-fired electric generating units capable of producing enough electricity for about 660,000 customers. For more information on Comanche Station, you can view the power plant’s fact sheet. The emissions information available on our web site will apply to Comanche Station’s current two units, until Comanche Unit 3 goes into service in 2009.

Comanche Unit 3 will feature state-of-the-art emission controls. We will also install additional emission controls on the two existing units at the plant. As a result, overall sulfur dioxide (SO2) and nitrogen oxide (NOx) emissions at Comanche Station will be lower than they are today, even when electric generation at the entire facility more than doubles.

For more information about the environmental controls planned for Comanche Station, download the air permit fact sheet (439K PDF).

For information about air emissions in general, visit the EPA’s web site at: http://www.epa.gov/ebtpages/air.html.

Emissions Summary

Power plant emissions are monitored by specialized equipment located on our power plant stacks. Continuous emission monitors measure emissions of various substances found in flue gas before it leaves the stack. This information is transferred to computers located at our facilities. We use this data to continuously monitor our operations and to provide emissions information to federal and state governments to ensure our compliance with air regulations.

The following chart summarizes Comanche Station emissions data for 2008.

Quarter 1 = Jan. 1 through March 31, 2008. YTD = year-to-date

**Note: There is no data substitution being performed for the missing Hg mass values.

Quarter 4 = Oct. 1 through Dec. 31, 2007. YTD = year-to-date

**Note: Hg mass values are biased low belcause there is no data substitution being performed for the missing mercury data periods.  The program is still being developed by EPA.

**Note: Hg data not available 1st quarter 2007 due to instrument failure issues.

Comanche Coal Unit 2 was down for a scheduled 9 week outage, from 9/6/07 through the end of the quarter.

Quarter 3 = Jul. 1 through Sep. 30, 2007. YTD = year-to-date

**Note: Hg mass values are biased low because there is no data substitution being performed for the missing mercury data periods.

Comanche Coal Unit 2 was down for a scheduled 9 week outage, from 9/6/07 through the end of the quarter.

Quarter 2 = Apr. 1 through Jun. 30, 2007. YTD = year-to-date

*Note: Hg data not available 1st quarter 2007 due to instrument failure issues.

Quarter 1 = Jan. 1 through Mar. 31, 2007. YTD = year-to-date.

*Note:Hg data not available 1st quarter 2007 due to instrument failure issues.

Mercury - Mercury emissions are calculated annually and reported through the Toxics Release Inventory. The latest available Comanche Station information is on our web site. We have installed mercury emission monitors on both Comanche units and began reporting data January 2007. These monitors will be used as we test mercury removal control technologies. Measured emissions will eventually be publicly reported to the EPA as part of our compliance with the Clean Air Mercury Rule.

You can view the Excess Emission Reports for more information.

Excess Emissions Reports - We file Excess Emissions Reports with the Colorado Department of Public Health and Environment (CDPHE) quarterly concerning each power plant we operate in Colorado. The report describes periods of time when our generating facilities exceeded their emission limits, the emissions involved, the duration and the cause. Excess emissions can occur due to equipment problems or human error. The reports also note periods of time when emission monitors were unavailable to measure emissions due to monitor malfunctions, daily calibrations, routine maintenance and other required quality assurance checks.

You can view the Excess Emission Reports for more information.

Emission Graphs

All files below are PDFs.

SO₂ Sulfur Dioxide

SO₂ lbs/mmbtu emission rate and limit (3-hr. rolling ave.)