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Progress Report

Emission Controls and Monitoring

Emission Controls and Monitoring Figures

Source: EPA, 2017
Last updated: 05/2017

Related Figures

SO₂ Emissions Controls in the ARP and CSAPR SO₂ Program in 2015
CSAPR SO₂ Program Monitoring Methodology in 2015
NOₓ Emissions Controls in CSAPR NOₓ Annual Program in 2015
CSAPR NOₓ Annual Program Monitoring Methodology in 2015
NOₓ Emissions Controls in CSAPR NOₓ Ozone Season Program in 2015
CSAPR NOₓ Ozone Season Program Monitoring Methodology in 2015

Key Points

ARP and CSAPR SO₂ Program Controls and Monitoring

  • Of all coal-fired generation (measured in gross megawatt hours, or MWh) in 2015 from sources participating in the ARP and CSAPR SO₂ program, 78 percent was produced by units with controls.
  • Units with advanced flue gas desulfurization technologies (FGDs), also known as scrubbers, accounted for 55 percent of coal-fired units and 76 percent of coal-fired generation in 2015.
  • In 2015, 32 percent of CSAPR units (including 100 percent of coal-fired units) monitored SO₂ emissions using CEMS while the vast majority (99 percent) of SO₂ emissions were measured by CEMS.

CSAPR NOₓ Annual Program Controls and Monitoring

  • Of all the fossil fuel-fired generation (as measured in gross megawatt hours, or MWh) from sources participating in CSAPR NOₓ annual program, 70 percent was produced in 2015 by units with advanced pollution controls (either selective catalytic reduction [SCR] or selective non-catalytic reduction [SNCR])
  • In 2015, the 346 coal-fired units with advanced pollution controls (either SCRs or SNCRs) accounted for 70 percent of coal-fired generation. At oil- and natural gas-fired units, SCR- and SNCR- controlled units produced 72 percent of generation.
  • In 2015, 72 percent of CSAPR units (including 100 percent of coal-fired units) monitored NOₓ emissions using CEMS while the vast majority (99 percent) of NOₓ emissions were measured by CEMS.

CSAPR NOₓ Ozone Season Program Controls and Monitoring

  • Of all the fossil fuel-fired generation (as measured in gross megawatt hours, or MWh) from sources participating in CSAPR NOₓ ozone season program, 69 percent was produced in 2015 by units with advanced pollution controls (either SCRs or SNCRs).
  • In 2015, units with advanced pollution controls (either SCR or SNCR) accounted for 69 percent of coal-fired generation. At oil- and natural gas-fired units, SCR- and SNCR- controlled units produced 69 percent of generation.
  • In 2015, 73 percent of CSAPR units (including 100 percent of coal-fired units) monitored ozone season NOₓ emissions using CEMS while the vast majority (99 percent) of ozone season NOₓ emissions were measured by CEMS.

Analysis and Background Information

Continuous Emission Monitoring Systems (CEMS)

Accurate and consistent emissions monitoring is the foundation of a successful cap and trade program. EPA has developed detailed procedures codified in federal regulations (40 CFR Part 75) to ensure that sources monitor and report emissions with a high degree of precision, reliability, accessibility, and timeliness. Sources are required to use CEMS or other approved methods to record and report pollutant emissions data. Sources conduct stringent quality assurance tests of their monitoring systems to ensure the accuracy of emissions data and to provide assurance to market participants that a ton of emissions measured at one facility is equivalent to a ton measured at a different facility. EPA conducts comprehensive electronic and field data audits to validate the reported data.

While some units with low levels of SO₂ and NOₓ emissions were allowed to use other approved monitoring methods, the vast majority of SO₂ and NOₓ emissions were measured by CEMS.

SO₂ Emission Controls

Sources in the ARP and CSAPR SO₂ program have a number of SO₂ emission control options available. These include switching to low sulfur coal, installing and operating various types of FGDs, or injecting limestone in fluidized bed boilers. FGDs – also known as scrubbers – on coal-fired generators are the principal means of controlling SO₂ emissions and tend to be present on the highest generating coal-fired units.

NOₓ Emission Controls

Sources in the ARP and CSAPR NOₓ annual and ozone season programs have a variety of options by which to reduce NOₓ emissions, including advanced controls such as SCR or SNCR, combustion controls, and others.

More Information

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