Progress Report

Emission Controls and Monitoring

Emission Controls and Monitoring Figures

Source: EPA, 2018
Last updated: 05/2018

Related Figures

SO₂ Emissions Controls in the ARP and CSAPR SO₂ Program in 2016
CSAPR SO₂ Program Monitoring Methodology in 2016
NOₓ Emissions Controls in CSAPR NOₓ Annual Program in 2016
CSAPR NOₓ Annual Program Monitoring Methodology in 2016
NOₓ Emissions Controls in CSAPR NOₓ Ozone Season Program in 2016
CSAPR NOₓ Ozone Season Program Monitoring Methodology in 2016

Highlights

ARP and CSAPR SO₂ Program Controls and Monitoring

  • Units with advanced flue gas desulfurization (FGD) controls (also known as scrubbers) accounted for 68 percent of coal-fired units and 84 percent of coal-fired generation, measured in megawatt hours, or MWh, in 2016.
  • In 2016, 30 percent of CSAPR units (including 100 percent of coal-fired units) monitored SO₂ emissions using CEMS. Ninety-nine percent of SO₂ emissions were measured by CEMS.

CSAPR NOₓ Annual Program Controls and Monitoring

  • Seventy-two percent of fossil fuel-fired generation (as measured in megawatt hours, or MWh) was produced by units with advanced pollution controls (either selective catalytic reduction [SCR] or selective non-catalytic reduction [SNCR]).
  • In 2016, the 325 coal-fired units with advanced add-on controls (either SCRs or SNCRs) generated 72 percent of coal-fired generation. At oil- and natural gas-fired units, SCR- and SNCR- controlled units produced 72 percent of generation.
  • In 2016, 72 percent of CSAPR units (including 100 percent of coal-fired units) monitored NOₓ emissions using CEMS. Ninety-nine percent of NOₓ emissions were measured by CEMS.

CSAPR NOₓ Ozone Season Program Controls and Monitoring

  • Seventy percent of all the fossil fuel-fired generation (as measured in megawatt hours, or MWh) was produced by units with advanced pollution controls (either SCRs or SNCRs).
  • In 2016, units with advanced add-on controls (either SCR or SNCR) accounted for 68 percent of coal-fired generation. At oil- and natural gas-fired units, SCR- and SNCR- controlled units produced 69 percent of generation.
  • In 2016, 73 percent of CSAPR units (including 100 percent of coal-fired units) monitored ozone season NOₓ emissions using CEMS. Ninety-eight 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 are allowed to use other approved monitoring methods, the vast majority of SO₂ and NOₓ emissions are 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, employing various types of FGDs, or utilizing fluidized bed limestone units. 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 post-combustion controls such as SCR or SNCR, and combustion controls, such as low NOₓ burners.

More Information