core_epacems__hourly_emissions
Return to SearchHourly time series of emissions and plant operational data as required by 40 CFR Part 75.
- Most-recent data:
2026
- Processing:
Data has been cleaned and organized into well-modeled tables that serve as building blocks for downstream wide tables and analyses.
- Source:
EPA Hourly Continuous Emission Monitoring System (CEMS)
- Primary key:
plant_id_epa, emissions_unit_id_epa, operating_datetime_utc
Usage Warnings
Large table; do not attempt to open with Excel.
Not all IDs are present.
Contains information from multiple raw inputs.
Additional Details
Continuous Emissions Monitoring Systems (CEMS) are used to determine the rate of gas or particulate matter exiting a point source of emissions. The EPA Clean Air Markets Division (CAMD) has collected data on power plant emissions from CEMS units stretching back to 1995. The CEMS dataset includes hourly gross load, SO2, CO2, and NOx emissions associated with a given emissions-unit during startup, shutdown, and instances of malfunction. An EPA CEMS emissions-unit or smokestack unit is not the same as an EIA unit. See core_epa__assn_eia_epacamd for details about how to connect CEMS data to corresponding EIA units.
Only fossil-combustion units over 25 MW are required to install and use CEMS, so there are some units that do report in EIA-860 or EIA-923 that do not have any CEMS data.
Columns
The unique six-digit facility identification number, also called an ORISPL, assigned by the Energy Information Administration.
The ORISPL ID used by EPA to refer to the plant. Usually but not always the same as plant_id_eia.
Emissions (smokestack) unit monitored by EPA CEMS.
Date and time measurement began (UTC).
Year the data was reported in, used for partitioning EPA CEMS.
Two letter US state abbreviation.
Length of time interval measured.
Average power in megawatts delivered during time interval measured.
The energy contained in fuel burned, measured in million BTU.
Total steam pressure produced by a unit during the reported hour.
Sulfur dioxide emissions in pounds.
Identifies whether the reported value of emissions was measured, calculated, or measured and substitute.
NOx emissions in pounds.
Identifies whether the reported value of emissions was measured, calculated, or measured and substitute.
Carbon dioxide emissions in short tons.
Identifies whether the reported value of emissions was measured, calculated, or measured and substitute.