out_epacems__yearly_operational_characteristics
Return to SearchAnnual time series of estimated operational characteristics for EPA CEMS emissions units.
- Most-recent data:
2025
- Processing:
Data has been expanded into a wide/denormalized format, with IDs and codes accompanied by human-readable names and descriptions.
- Source:
EPA Hourly Continuous Emission Monitoring System (CEMS)
- Primary key:
report_year, plant_id_epa, emissions_unit_id_epa
Usage Warnings
Contains estimated values.
This table is experimental and/or a work in progress and may change in the future.
This table estimates values for each calendar year from a trailing 3-year window of EPA CEMS reporting ending in that year.
Additional Details
This table summarizes several inferred operational characteristics for each EPA CEMS emissions unit for every calendar year that has a full trailing window of usable EPA CEMS quarters available. It uses hourly CEMS gross load and fuel heat content over a trailing three calendar year window to estimate values for the final year of that window. The earliest year for which operational characteristics are estimated is constrained by how far back the trailing window can reach. The first three years of EPA CEMS reporting (1995-1997) are excluded as unusable due to poor data quality and inconsistent unit coverage. This means the earliest year for which we estimate operational characteristics is 2000, not 1997.
The values are not directly reported to source agencies. They are derived from observed hourly operations. These variables should be treated as an analytical estimate rather than as reported plant characteristics.
For methodological details, see /methodology/operational_characteristics.
Columns
Four-digit year in which the data was reported.
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.
The unique six-digit facility identification number, also called an ORISPL, assigned by the Energy Information Administration.
Two letter US state abbreviation.
Maximum observed gross load for an EPA CEMS emissions unit.
Estimated minimum stable operating level as a fraction of maximum gross load.
Minimum observed duration of a consecutive run at or above the minimum stable level.
Minimum observed duration of a consecutive non-operating run.
Estimated heat rate at the highest observed load-factor bin for an EPA CEMS emissions unit.
Estimated heat rate at the minimum stable operating level for an EPA CEMS emissions unit.
Median ramp rate among the steepest 5% of observed upward ramps expressed as a fraction of maximum gross load per minute.
Median ramp rate among the steepest 5% of observed downward ramps expressed as a fraction of maximum gross load per minute.