Greenhouse 100 Polluters Index Technical Notes

The Greenhouse Gas Reporting Program database (GHGRP), compiled by the U.S. Environmental Protection Agency (EPA) in response to the FY2008 Consolidated Appropriations Act (H.R. 2764; Public Law 110--161), annually reports the weight (in metric tons) of greenhouse gasses from both large direct emission sources and suppliers of fossil fuels. From an EPA About the Program page: "In general, facilities that directly emit 25,000 metric tons of carbon dioxide equivalent or more per year are required to submit annual reports to EPA. In addition, suppliers of certain products that would result in GHG emissions if released, combusted or oxidized are required to report." Data has been reported so far (as of January 2016) for 2010 through 2014. 

Our analysis uses 2014 reports from large direct emission sources (i.e. facilities) from this database. Suppliers were not included since some suppliers provide fuel to direct emission sources, and this would result in the fuel being counted twice. The GHGRP database provides data on more industrial sectors than previous U.S. facility-specific databases since it covers more than the electricity generation sector -- it also covers petroleum and natural gas systems, refineries (we used data from them as direct sources of emissions, not as suppliers), chemicals, waste, metals, minerals, and pulp and paper.

We added up direct carbon dioxide emissions plus emissions of methane, nitrous oxide, and fluorinated gases as carbon dioxide equivalents as reported within the GHGRP database. Biogenic carbon dioxide was not included within these totals.

We obtained the GHGRP data from theEnvirofacts Customized Search Summary Subjects on November 27, 2015. These data were last updated by EPA on August 16, 2015.  

Using information on company ownership of facilities from the GHGRP reports, company websites, and news reports, we matched each facility to its parent company. Each facility was assigned either one or two parents as follows: 

  • If more than 50% of a facility was controlled by a single parent, that parent was assumed to have final control over the facility's operations, and was assigned full responsibility for the facility's pollution.
  • If two companies each controlled 50% of a facility (i.e. it was a 50/50 joint venture), then its pollution was divided between the two companies.
  • If a single company controlled 50% of a facility and no other single entity controlled the other 50%, that company was considered to be the parent of the facility.
  • If no parent controlled 50% of a facility, the facility was considered to be its own parent.

The GHGRP database includes detailed ownership percentages of facilities by multiple parents, and we could have used these to assign each facility's pollution to many parents instead of one or two. However, these percentages reported within the GHGRP are percentages of ownership, not percentages of emissions. It is possible for power plants to have multiple generating units owned by different companies in which the percentage of ownership of the facility as a whole does not match the percentage of the facility's emissions from each set of generating units. Therefore, we consider that assigning pollution by corporate majority ownership better reflects the data.

Corporate ownership of facilities was reported to the GHGRP as it was on December 31, 2014. In some cases we updated parent companies according to mergers, acquisitions, and corporate name changes that took place in 2015, under the principle that when one company acquires another, it takes responsibility for that company's past pollution. We also combined some U.S. subsidiaries of common foreign companies together.

The Greenhouse 100 was created by ranking the 100 largest parent companies for carbon dioxide equivalent emissions (excluding biogenic carbon dioxide) from the 2014 GHGRP database of large fixed facilities, after parent companies were assigned as above. The Greenhouse 100 list and application lists both parent company carbon dioxide equivalent totals and percentages of the database. The application also shows data from individual facilities owned by each parent company and from industrial sectors at each. For comparison, the application also shows each parent company's percentage contribution to total U.S. greenhouse gas emissions including all sources, such as transportation, commercial, agricultural and residential emission, as taken from the 2013 U.S. Inventory. (Note that this treats 2014 emission numbers as percentages of an estimated 2013 total, but the 2014 U.S. Inventory had not yet been released at the time of this report.)  This percentage (of the parent company's emissions compared to all emissions within the U.S.) is listed in the Greenhouse 100 table.

For anthropogenic global climate change, the locations of the facilities emitting greenhouse gases do not matter. But these facilities also commonly emit co-pollutants, such as particulate matter, carbon monoxide, and sulfur oxides, as well as other criteria and toxic air pollutants, that have harmful effects on people living nearby. For this reason we calculated facility locational environmental justice (EJ) ratios by using American Community Survey 2010-2014 5-year average block group data on people living within 10 miles of each facility. The minority EJ ratio is the percentage share of racial and ethnic minorities in the total population living within the 10-mile radius around each facility; in the advanced data display, this is disaggregated into specific minority groups. Similarly, the poverty EJ ratio is the percentage of people living below the poverty line within this radius, and the "near poor" percentage is the percentage of people living up to twice the poverty level.

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