California Power Map: Glossary and Sources

General Information

The California Power Map was created by PSE Healthy Energy with funding from The Energy Foundation and The 11th Hour Project, a program of the Schmidt Family Foundation. The project’s goal is to facilitate understanding of the operations and emissions of California’s fossil fuel and bioenergy power plants in relation to nearby communities and the state as a whole.

The California Power Map includes the state’s fossil fuel and bioenergy plants that are 10 MW and larger. It does NOT include nuclear, solar, wind, hydro, or geothermal generation.

This page provides definitions and descriptions of the data used in the California Power Map as well as specific information about the data sources used. For additional questions please email krieger@psehealthyenergy.org.

Definitions and Description of Data

  • Air basin: Regions designated by the California Air Resources Board for pollution management (see: California Air Basin Map).
  • Balancing authority: Grid operator who manages transmission-level grid balancing to ensure that electricity supply will match the load in any given area. The primary balancing authority in California is the California Independent System Operator.
  • Biogas facility: Biogas power plants in California typically burn products like gas produced from landfills or biodigesters.
  • Biomass facility: Biomass power plants in California burn biomass products like wood for electricity production.
  • Carbon dioxide (CO2): A greenhouse gas emitted from the combustion of fossil fuels, among other sources. Power plant emission data reported from the U.S. Environmental Protection Agency Air Markets Program Database and supplemented, when missing, from the California Air Resources Board Pollution Mapping Tool.
  • Cogen facility: In addition to electricity, cogeneration plants produce steam, which is typically used in industrial applications like oil production or for space heating.
  • CalEnviroScreen 3.0: Environmental justice screening tool developed by the California Office of Environmental Health Hazard Assessment to evaluate the relative vulnerability of communities and their cumulative environmental health and socioeconomic burdens. Score is calculated based on an environmental burden score and a demographic score. Census tracts are typically ranked by percentile as compared to all of the census tracts in California. Scores above the 75th percentile overall (or above the 95th percentile in tracts missing a demographic score) indicate a disadvantaged or vulnerable community. (See: CalEnviroScreen 3.0 for tool and methodology.)
  • Capacity: Metric of maximum power capability of an electricity generation facility, typically reported in megawatts (MW).
  • Capacity factor:A measure of how frequently a plant operates, defined as the fraction of electricity a power plant produces as compared to the maximum electricity it would produce if it ran constantly. Calculated from data reported by the U.S. Environmental Protection Agency Air Markets Program Database and supplemented, when missing, from the California Air Resources Board Pollution Mapping Tool.

           [Capacity factor]

= [Actual generation]/[Maximum potential generation]

= [MWh]/[MW*365*24]

  • Criteria air pollutants: Six common air pollutants known to harm human health for which the U.S. Environmental Protection Agency has established National Ambient Air Quality Standards. They include ground-level ozone, particulate matter, nitrogen dioxide, sulfur dioxide, carbon monoxide, and lead.
  • Disadvantaged community: Defined in the State of California as being a census tract ranked in the top 25% most vulnerable according to CalEnviroScreen or the top 5% environmental burden score for census tracts lacking a demographic score.
  • Generation:The amount of electricity produced at a power plant, typically reported in megawatt-hours (MWh). Data reported by the U.S. Environmental Protection Agency Air Markets Program Database and supplemented, when missing, from the California Air Resources Board Pollution Mapping Tool.
  • Heat rate: Measure of power plant efficiency, defined as the amount of fuel burned in million British Thermal Units per megawatt-hour of electricity generation (MMBtu/MWh). Calculated from data reported by the U.S. Environmental Protection Agency Air Markets Program Database and supplemented, when missing, from the California Air Resources Board Pollution Mapping Tool.
  • High ozone days: Defined here as days where the eight-hour ozone concentration in any location in an air basin exceeds the federal air quality standard of 70 parts per million. Data retrieved from the U.S. Environmental Protection Agency Air Data.
  • High particulate matter (PM) days: Defined here as days where the 24-hour PM2.5concentration in any location in an air basin exceeds the federal air quality standard of 35 μg/m3. Data retrieved from the U.S. Environmental Protection Agency Air Data.
  • Megawatt: A measure of power, which is the rate of electricity produced and used to characterize the maximum power capacity of a plant.
  • Megawatt-hour (MWh): A measure of electricity generation; a 100-MW plant operating for one hour produces 100 MWh of electricity.
  • Municipal solid waste facility (MSW): Produces power by burning solid waste as fuel.
  • Natural gas combined cycle (NGCC): Natural gas-fired power plant that includes both a combustion turbine and uses waste steam in a secondary turbine; typically used for baseload or load following.
  • Nitrogen oxides (NOx): A criteria air pollutant that also leads to the secondary formation of ozone and particulate matter in the atmosphere.
  • Once-through cooling facility: A power plant that withdraws cold water from a nearby source (in California, typically the ocean) and uses it for plant cooling before returning the water back to the environment. California power plants are all required to phase out once-through cooling systems in the coming years.
  • Ozone (O3): A criteria air pollutant that typically forms from the reaction of NOx with volatile organic compounds (VOCs) in sunlight, and which can cause respiratory health problems.
  • Particulate matter (PM): A criteria air pollutant consisting of very small particles which can cause cardiovascular and respiratory health problems and lead to premature death. Particulate matter can be emitted directly from fossil fuel combustion (among other sources) or form as a secondary pollutant from sulfur and nitrogen oxides. The subscript of the pollutant refers to the diameter, so that PM2.5indicates particles that have a diameter of 2.5 microns or less, and PM10refers to particles that have a diameter of 10 microns or less. Here we typically use PM to refer to 2.5.
  • Peaker: Peaker power plants are defined here as simple cycle natural gas plants, which are typically used only a small fraction of the time and are turned on to meet the highest “peak” load — often during hot summer days.
  • Reliability areas and sub-areas: Regions designated by the California Independent System Operator to identify local power capacity needs to meet nearby peak demand.
  • Starts: Defined here as the number of times per year a power plant moves from zero generation in one hour to a non-zero value the following hour, as reported in the US Environmental Protection AgencyAir Markets Program Database.
  • Utility: Entity responsible for electricity service in a given territory.

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Data Sources and Dates

Data: Hourly power plant generation (MWh) and emissions (CO2, NO2, SOx).
Source:U.S. Environmental Protection Agency. Air Markets Program Data. 2018.
Available at:ampd.epa.gov/ampd
Most recent download:February 21, 2018
Data years:2010-2017

Data: Power plant ownership
Source:U.S. Energy Information Administration. Form EIA-923 detailed data: 2017 Early Release. 2018.
Available at:www.eia.gov/electricity/data/eia923
Most recent download:July 1, 2018
Data year:2017

Data: Power plant ownership, capacity
Source:U.S. Energy Information Administration. Form EIA-860 detailed data: 2017 Early Release. 2018.
Available at:www.eia.gov/electricity/data/eia860
Most recent download:July 1, 2018
Data year:2017

Data: Power plant status
Source:CALISO. Announced retirement and mothball list. 2018.
Available at:www.caiso.com/Documents/AnnouncedRetirementAndMothballList.xlsx
Most recent download:July 20, 2018

Data: Power plant name, locational attributes, capacity, plant type, congressional districts,
Source:California Energy Commission. Database of California power plants. 2018.
Available at:www.energy.ca.gov/almanac/power_plant_data/Power_Plants.xlsx
Most recent download:January 9, 2018

Data: Air monitor locations
Source:California Air Resources Board. Air monitor site list generator. 2018.
Available at:www.arb.ca.gov/qaweb/sitelist_create.php
Most recent download:February 12, 2018

Data: Proposed power plants
Source:California Energy Commission. Status of all projects. 2018.
Available at:www.energy.ca.gov/sitingcases/all_projects.html
Last checked:August 7, 2018

Data: Daily ozone and particulate matter concentrations
Source:U.S. Environmental Protection Agency. Pre-generated data files: tables of daily and daily summary data. 2018.
Available at:aqs.epa.gov/aqsweb/airdata/download_files.html#Daily
Most recent download:February 2, 2018
Data years:2010-2017

Data: Local capacity requirements
Source:California Independent System Operator. 2019 local capacity technical analysis: final report and study results. 2018.
Available at:www.caiso.com/informed/Pages/StakeholderProcesses/FlexibleCapacityNeedsAssessmentProcess.aspx
Most recent download:August 7, 2018

Data: Mothball status of biomass plants
Source:Cal Biomass Energy Alliance. Biomass facilities. 2018
Available at:www.calbiomass.org/facilities-map
Most recent download:July 15, 2018

Data: California air basin geography
Source:California Air Resources Board. California Air Basins. 2018.
Available at:www.arb.ca.gov/knowzone/basin/basin.htm
Last checked:August 7, 2018

Data: Power plant ID cross-reference list
Source:California Energy Commission. California Energy Commission power plant ID cross reference table. 2018.
Available at:www.energy.ca.gov/almanac/electricity_data/web_qfer/Energy_Commission_Power_Plant_ID_Cross_Reference_Table.xls
Most recent download:June 27, 2018

Data: Power plant capacity and generation
Source:California Energy Commission. Annual generation – plant unit. 2018.
Available at:www.energy.ca.gov/almanac/electricity_data/web_qfer/Annual_Generation-Plant_Unit.php
Most recent download:July 3, 2018
Data years:2010-2017

Data: CalEnviroScreen 3.0
Source:Office of Environmental Health Hazard Assessment. CalEnviroScreen 3.0. 2018.
Available at:oehha.ca.gov/calenviroscreen/report/calenviroscreen-30
Most recent download:March 21, 2018
Data years:2006-2016 (varies by indicator)

Data: Annual power plant criteria pollutant emissions
Source:California Air Resources Board. CARB pollution mapping tool. 2018.
Available at:www.arb.ca.gov/ei/tools/pollution_map
Most recent download:July 9, 2018
Data years:2010-2016

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