Emissions & Generation Resource Integrated Database (eGRID) Questions and Answers
Related Information
- What is eGRID?
- Why eGRID?
- What information is contained in eGRID?
- Who uses eGRID?
- What years are available for eGRID?
- What is new in eGRID2014?
- Has the grid gross loss methodology changed?
- Has the eGRID naming convention changed?
- Is there additional eGRID data available?
- What do the eGRID subregion and NERC region maps look like?
- What are the changes to the eGRID2014 subregion map?
- What are the regional emission rates and resource mix?
- How can I receive eGRID related news from EPA?
- What other emissions data are available from EPA?
- What other EPA tools are available to estimate avoided emissions from EE/RE programs?
- How can I provide feedback or ask questions?
What is eGRID?
The Emissions & Generation Resource Integrated Database (eGRID) is a comprehensive inventory of environmental attributes of electric power systems. The preeminent source of air emission data for the electric power sector, eGRID is based on available plant-specific data for all U.S. electricity generating plants that provide power to the electric grid and report data to the U.S. government. eGRID uses data from the Energy Information Administration (EIA) Forms EIA-860 and EIA-923 and EPA’s Clean Air Markets Program Data. Emission data from EPA are carefully integrated with generation data from EIA to produce useful values like pounds of emissions per megawatt-hour of electricity generation (lb/MWh), which allows direct comparison of the environmental attributes of electricity generation. eGRID also provides aggregated data by state, U.S. total, and by three different sets of electric grid boundaries (i.e., balancing authority area, NERC region, and eGRID subregion).
Why eGRID?
Many consumers have a choice regarding the source of their electricity, and some seek cleaner sources, such as wind and solar power. EPA’s Power Profiler application, which uses eGRID data, helps individual consumers understand the environmental impacts of their own electricity usage.
Electricity generation is the dominant industrial source of air emissions in the United States today. Whenever you switch on an electrical appliance, chances are you are contributing to air pollution and greenhouse gas emissions. By documenting the environmental attributes of electric power generation, eGRID can help consumers and researchers to better understand the relationship between electricity and the environment.
In the United States, electricity is generated in many different ways, with a wide variation in environmental impacts. In many states, power companies are required to disclose the environmental attributes of their retail electricity products. eGRID data can be used to support the following activities:
- Greenhouse gas registries and inventories,
- Carbon footprinting,
- Consumer information disclosure,
- Renewable portfolio standards,
- Development of emission inventories and emission standards,
- Analysis of changing power markets, and
- Estimation of avoided emissions.
What information is contained in eGRID?
For every power plant in the United States, eGRID provides:
- A detailed emissions profile, covering nitrogen oxides (NOX), sulfur dioxide (SO2), carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), and mercury (Hg). (Hg emissions are available prior to year 2007). Emissions are reported in tons (pounds for CH4, N2O, and Hg), output emission rates in lb/MWh (pounds per gigawatt-hour for CH4, N2O, and Hg), and input emission rates in pounds per million British thermal units (lb/MMBtu) (pounds per billion Btu for CH4, N2O, and Hg),
- Generation resource mix, in megawatt-hours and percent, and
- Identification, ownership, corporate affiliation, and location information.
eGRID provides separate data files at the unit and generator level. Emissions and resource mix data from the plant level are aggregated by electric generating company, parent company (company level data is available prior to year 2009), state, U.S. total, and three types of power grid regions:
- NERC region, as designated by the North American Electric Reliability Corporation (plus Alaska and Hawaii),
- eGRID subregion, and
- Balancing authority area (generally smaller regions of the power grid in which all power plants are centrally dispatched).
The eGRID all edition ZIP file currently contains the data and supplementary files (e.g., technical support documents, maps, summary tables, and release notes) for years 2014, 2012, 2010, 2009, 2007, 2005, 2004, 2000, 1999, 1998, 1997, and 1996. Net imports-exports by state are provided for years 2007, 2005, and 2004. Data on net imports-exports by state and power interchange between grid regions are included in eGRID data for years 1996 through 2000.
The eGRID2014 ZIP file contains year 2014 data and supplementary files.
Who uses eGRID?
eGRID is valuable to those in the Federal Government, state and local governments, non-governmental organizations, companies, and academia. It is also useful to individuals seeking environmental information about the electric power sector in the United States. eGRID is most often used to estimate indirect emissions from electricity purchases, in GHG inventories, for carbon footprinting, and for estimating avoided emissions from programs and projects that reduce consumption of grid-supplied electricity. eGRID data is cited by many emission inventory and registry protocols, various emission calculation tools and applications, hundreds of academic papers, and consultants; it is used for many research applications and efforts.
Within EPA, eGRID data are used by the following applications and programs: Power Profiler, Center for Corporate Climate Leadership, Portfolio Manager, the Household Greenhouse Gas Emissions Calculator, and the Greenhouse Gas Equivalencies Calculator.
When EPA announced the winners of its 2011 “Apps for the Environment” challenge, two winning apps — Light Bulb Finder Exit and Joulebug Exitused eGRID data.
In 2015, Executive Order 13693 was issued, requiring Federal agencies to reduce their greenhouse gas emissions from direct and indirect activities. The order requires that Federal agencies report their building information in EPA’s Portfolio Manager which uses eGRID to estimate emission reductions.
Fueleconomy.gov, a partnership between EPA and DOE, uses eGRID data to estimate the total GHG emissions from electric and plug-in hybrid vehicles in its Greenhouse Gas Emissions for Electric and Plug-in Hybrid Electric Vehicles calculator.
eGRID is also used by other Federal Government agencies such as Oak Ridge National Laboratory (ORNL) for their Combined Heat and Power and Emissions Savings Calculator, the National Energy Technology Laboratory (NETL) for their sponsored Distributed National Carbon Sequestration Database and Geographic Information System (NATCARB), and the National Renewable Energy Laboratory (NREL) for their micropower distributed generation optimization model named HOMER.
One of the most popular recent uses of eGRID is to determine the indirect GHG emissions from electricity purchases and avoided GHG emissions from projects and programs that reduce the demand for grid supplied electricity. For example, the California Air Resources Board, Climate Registry, Climate Action Reserve, and Greenhouse Gas Protocol cite eGRID for use in estimating scope 2 GHG emissions from electricity purchases in the United States. Most carbon footprint calculators that are applicable to the United States use eGRID data.
States and local governments rely on eGRID data for electricity labeling (environmental disclosure programs), emission inventories, and registries as well as for efforts to analyze air emissions from the electric power sector. Several states have used eGRID to publish state specific emission information or have used eGRID to inform policy decisions.
Renewable energy certificates (RECS) tracking systems, such as ISO-New England’s Generation Information System (GIS) and PJM Interconnection’s Generation Attribute Tracking System (GATS), use eGRID data.
eGRID is used by many nongovernmental organizations in their tools and analysis. One example is Carbon Footprint Visualizations Exitby Carbon Visuals, which illustrates accurate volumetric images to visualize the carbon footprint of all U.S. power stations. Another example is The University of California, Berkeley’s CoolClimate Carbon Footprint Maps. Exit
What years are available for eGRID?
The latest version of eGRID (eGRID2014) was the eleventh edition released in January of 2017 with data from 2014. The data is available on the eGRID website as individual files or as a single eGRID2014 ZIP file. eGRID data for the years 1996 thru 2000, 2004, 2005, 2007, 2009, 2010, 2012 and 2014 are available in the all eGRID files ZIP file.
What is new in eGRID2014?
eGRID2014 is updated with 2014 data and several methodology improvements:
- In this edition, more effort was taken to report generator- and unit-level data. In previous editions of eGRID, these data were only reported in eGRID if they were reported at the generator or unit level in the EPA/CAMD or EIA data. In eGRID2014, the entire universe of generators and units that report to EPA/CAMD and EIA is included. Where generator- or unit-level data on generation, emissions, or heat input are available, we report them in eGRID. For all other generators or units, we distribute generation and heat input to each generator or unit using prime mover-level data. We use emission factors to estimate emissions based on heat input. Generation from the Generator file and the emissions and heat input from the Unit file now sum to equal the plant-level generation, emissions, and heat input.
- In previous editions of eGRID, for CHP units where EIA reported that the heat input for electric power was equal to the total plant heat input, we estimated a ratio for the CHP adjustment. However, based on discussions with EIA, we have decided that for those CHP units where heat input for electric power is equal to the total heat input, we will not perform a CHP adjustment in eGRID2014.
- The methodology for calculating grid gross loss in eGRID2014 has changed. Please see the “Has the grid gross loss methodology changed?” FAQ for more details.
There are also several workbook/spreadsheet formatting changes in eGRID2014, including:
- Renaming the Boiler file to Unit file to accurately reflect that the data contains boilers (e.g. steam turbines) as well as gas turbines, internal combustion engines, combined cycle units, and renewable sources of electricity generation (wind, solar photovoltaic, and hydroelectric).
- Removing duplicate EPA and EIA data fields, as well as the field for ‘best’ data from the boiler spreadsheet, now called the unit spreadsheet as mentioned above. Now, only the ‘best’ data are reported along with the data source.
- Removing the owner and historical sequence ID fields that were reported in the Plant file in past editions of eGRID. The owner information is available as part of a separate Owner Information spreadsheet (XLS) (1 pg, 2 MB) and the historical sequence IDs are available as a separate Sequence IDs spreadsheet (XLS) (1 pg, 582 K) .
- Revising the approach for plant-level unadjusted heat input for renewable fuels. In previous editions of eGRID, the unadjusted heat input for renewable fuels in the Plant file (geothermal, nuclear, solar, water, and wind) was set to 0. In the current edition of eGRID, all renewable fuel heat input is reported directly from EIA-923 data in the Plant file. It should be noted that the emission factors for all pollutants for nuclear, solar, water, and wind are set to 0 and no emission data will be reported, even if there is positive heat input.
- Improving ozone-season generation and heat input methodologies. In previous editions of eGRID, the ozone-season generation and ozone-season heat input in the Unit and Plant file were reported in eGRID as monthly data if the plant reported monthly data to EIA and calculated by multiplying total generation or heat input by 5/12, representing the five-month ozone season, if the plant reported only annual data to EIA. However, since EIA includes a distribution of generation and heat input by month for plants that report annual data only, the generation and heat input ozone-season data in eGRID2014 are reported as the direct EIA monthly data for the months of May to September. The 5/12 methodology is no longer used.
- Renaming the power control area spreadsheet to the balancing authority spreadsheet to reflect the terminology used by the EIA and NERC.
- Adding fields to the eGRID Subregion file that report the nonbaseload generation by fuel type and the nonbaseload resource mix.
- Adding fields to the eGRID Subregion file that report the CH4 and N2O emission rates by fuel type.
- Adding an additional workbook that displays emissions, generation, and emission rates in metric units.
Please see the Technical Support Document for more details. Because there are some methodological changes in different editions of eGRID from year to year, please use caution when comparing data from different years.
Has the grid gross loss methodology changed?
Yes, the methodology for calculating grid gross loss has changed from previous editions of eGRID. Earlier eGRID estimates of grid gross loss used a formula that included a combination of data on generation, imports, and exports data from FERC and consumption data from EIA. eGRID2014 uses only EIA data, as well as a new formula. The use of one data source minimizes error due to differences in the way EIA and FERC collect data. EIA data was ultimately chosen as EIA collects data on utility losses specifically. EIA’s State Electricity Profiles (which are generated using data from EIA Form 861) were used to collect data on estimated losses and generation at the state level. These data were aggregated to generate grid gross loss estimates for each interconnect and the United States. The formula calculates the estimated losses as a percent of generation. Please see the Technical Support Document for more details on the data definitions and methodology.
Has the eGRID naming convention changed?
Yes, with the release of eGRID2012 (October 8, 2015), the naming convention has changed. The year noted in the title reflects the data year rather than the release year. For example, the eGRID file released in 2012 with 2009 data was previously named eGRID2012, using the new naming convention it’s now called eGRID2009.
eGRID2012 and subsequent editions (and associated materials) reference previous eGRID editions using the new naming convention and the files available for download from the website use the new naming convention; however, the content within the previous editions of eGRID, such as the technical support documents, has not been revised.
Is there additional eGRID data available?
Yes, several additional data files are available. Beginning with eGRID2014, the data is also presented in metric units and is available in the metric version of eGRID2014 (ZIP)(1 pg, 14 MB) . The Owner Information (XLS) (1 pp, 2 MB) and Historical Sequence ID fields (XLS) (1 pp, 582 K) that were reported in the Plant file in past editions of eGRID are now included as separate files. Also, in addition to the code descriptions available in the Technical Support Document, a Code Lookup file (XLS) (1 pg, 30 K) is available. As described in the “What do the eGRID subregion and NERC region maps look like?” question, the jpg and shapefiles for the eGRID subregion map and NERC map are available.
What do the eGRID subregion and NERC region maps look like?
These are representational maps, many of the boundaries shown on these maps are approximate because they are based on companies, not on strict geographical boundaries. The NERC Regions shapefile is an approximation (12/5/2016) distributed by EIA based on the NERC map.
What are the changes to the eGRID2014 subregion map?
The subregion map for eGRID2014 is very similar to the eGRID2012 subregion map. As with eGRID2012, zip codes where more than one eGRID subregion may apply are identified. While the majority of zip codes are located within only one eGRID subregion, in some cases a zip code may fall in multiple eGRID subregions because it is supplied by different service providers associated with different subregions. This usually occurs near the borders of two subregions. Cross-hatching on the map illustrates areas where there is more than one eGRID subregion. This is the same methodology used to produce the subregion map for eGRID2012. The only difference is that the map no longer identifies “secondary” and “tertiary” subregions; rather it simply indicates areas that fall into more than one eGRID subregion.
If you live in an area with multiple electric service providers (illustrated by cross-hatching on the map), the map isn’t sufficient to tell you the eGRID subregion associated with your location. For this information, you must enter your zip code and electric service provider information into Power Profiler to definitively determine your appropriate eGRID subregion.
Many of the boundaries shown on these maps are not based on strict geographical boundaries. Also, plants assigned to a particular eGRID subregion may not be connected by transmission lines to a particular power control area and may also be located far away from the utility service territories that the power control area serves. For example, the Intermountain Power Project plant’s power control area is the Los Angeles Department of Water and Power, yet this plant is located in Utah. A GIS shapefile for the eGRID subregions is available here, and a shapefile for the NERC regions is available here. While more detail has been added to the eGRID2014 subregion map, the methodology to determine the subregion emission rates and resource mix has not changed.
What are the regional emission rates and resource mix?
eGRID subregion, NERC region, and the U. S. summary information for eGRID2014 can be found in summary tables available as either an eGRID Summary Table (XLS) or eGRID Summary Table (PDF) format. The summary tables for data years 2014, 2012, 2010, 2009, 2007, 2005 and 2004 can be found in the all eGRID files (1996-2014) ZIP file.
How can I receive eGRID related news from EPA?
If you are interested in receiving email alerts when eGRID is updated or eGRID related news is released, please sign up using the eGRID Notification form.
What other emissions data are available from EPA?
Most of the eGRID emission data is from the Clean Air Markets Programs of EPA. In addition to the hourly emission data reported to EPA from power plants affected by the Acid Rain Program and/or the Cross-State Air Pollution Rule, the Clean Air Markets website presents progress reports, power plant emission trends, and emissions tracking highlights. Other EPA emission data sources also provide data on emissions associated with electricity generation. Air Trends Reports are EPA's "report card" on the status of air quality and air pollutant emissions. Reports are published annually, about ten months after year-end. U.S. Greenhouse Gas Inventory Reports include inventories of U.S. greenhouse gas emissions and sinks. Also, see the National Emissions Inventories for the U.S. and the Toxics Release Inventory
What other EPA tools are available to estimate avoided emissions from EE/RE programs?
EPA released the AVoided Emissions and geneRation Tool (AVERT) in 2014 for the purpose of calculating avoided NOX, SO2, and CO2 emissions of energy efficiency and renewable energy (EE/RE) policies and programs. In this Excel-based tool users can create custom calculations that reflect variations in hourly impacts of different EE programs or RE resources within one of AVERT’s ten regions. For example, users can select among wind, solar, and different EE savings options (“load impact profiles”) within the tool.
AVERT’s peer-reviewed methodology produces outputs that can be used for short-term Clean Air Act Plan demonstrations, such as NAAQS SIPs, state-wide EE/RE policies, and multi-state analysis. AVERT’s map, charts, and tables display the location of emission reductions at the regional, state, and county level on a monthly and annual basis.
How can I provide feedback or ask questions?
Your input and feedback is greatly appreciated. Please fill out this short survey to let us know how you use eGRID, what data you currently use, what features you would like in subsequent versions, and suggestions for improvements. Additionally, if you have questions or comments, you can submit them through this web form or email EPA directly.