Measurement-Based Methodology

Measurement-Based Methodology (Chapter 8.1)

Continuous emissions monitoring systems (CEMS) are the primary emissions monitoring method used in the power/utility sector. Local governments that report CO2 emissions data to the U.S. EPA according to 40 CFR Part 75 and/or state/province or local environmental agencies can use the same CO2 emissions information in their GHG inventory (www.epa.gov/airmarkets/emissions/rules.html). Either of the two following CEMS configurations can be used to determine annual CO2 emissions:

  1. A monitor measuring CO2 concentration percent by volume of flue gas and a flow monitoring system measuring the volumetric flow rate of flue gas can be used to determine CO2 mass emissions. Annual CO2 emissions are determined based on the operating time of the unit.
  2. A monitor measuring O2 concentration percent by volume of flue gas and a flow monitoring system measuring the volumetric flow rate of flue gas combined with theoretical CO2 and flue gas production by fuel characteristics can be used to determine CO2 flue gas emissions and CO2 mass emissions. Annual CO2 emissions are determined based on the operating time of the unit.

Note: The LGO Protocol recommends that local governments identify and report biomass CO2 emissions as biogenic emissions separate from fossil fuel emissions. See Calculating Emissions from Biofuels, Waste Fuels, and Biomass.