Comparing TRI and Greenhouse Gas Emissions in the 2015 TRI National Analysis
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Under the authority of the Clean Air Act, EPA's Greenhouse Gas Reporting Program (GHGRP) requires large emitters of greenhouse gases and suppliers of certain products to submit annual greenhouse gas reports to EPA. Emissions of greenhouse gases lead to elevated concentrations of these gases in the atmosphere, which alter the Earth's radiative balance and contribute to climate change. These elevated concentrations are reasonably anticipated to endanger the public health and welfare of current and future generations. The purpose of the GHGRP is to collect timely, industry-specific data to help us better understand the sources of greenhouse gas emissions. Comparing and integrating GHGRP data with Toxics Release Inventory (TRI) data about chemical releases from industrial facilities can provide a more complete picture of a facility’s environmental performance.
What do GWP and CO2e mean?
Each GHG has an associated global warming potential (GWP). The GWP is a relative measure of how much heat a GHG traps in the atmosphere relative to CO2 over a given time period. The GWP of CO2 is one. GHG emissions values are typically expressed in metric tons of carbon dioxide equivalent (CO2e) so that the impacts of different gases can be directly compared.
What chemicals were reported to GHGRP for 2015?
- Carbon dioxide = 91.3% of the mtCO2e total
- Methane = 7.2%
- Nitrogen Oxide (N2O) = 0.9%
- Fluorinated Gases (HFCs, PFCs, SF6) = 0.7%
- Over 8,000 facilities reported direct emissions of greenhouse gasesgreenhouse gasesGases in the Earth's atmosphere that produce the greenhouse effect. Changes in the concentration of certain greenhouse gases, due to human activity such as fossil fuel burning, increase the risk of global climate change. Greenhouse gases include water vapor, carbon dioxide, methane, nitrous oxide, halogenated fluorocarbons, ozone, perfluorinated carbons, and hydro fluorocarbons. (GHGs) to the atmosphere, totaling over 3.05 billion metric tons of carbon dioxide equivalentcarbon dioxide equivalentA unit of measurement that can be used to compare the emissions of various greenhouse gases based on how long they stay in the atmosphere and how much heat they can trap. For example, over a period of 100 years, 1 pound of methane will trap as much heat as 21 pounds of carbon dioxide. Thus, 1 pound of methane is equal to 21 pounds of carbon dioxide equivalents. (mtCO2e).
- This represents about half of the 6.87 billion mtCO2e that EPA estimated were released in the United States from all human-related sources per the 2014 annual U.S. Greenhouse Gas Inventory. The GHGRP does not require direct emissions reporting from all U.S. sources. For example, the transportation sector and agricultural sources of GHG emissions are not included in the GHGRP.
- The primary greenhouse gas reported to the GHGRP was carbon dioxide (CO2), which is released during fossil fuel combustion and various industrial processes.
TRI reporting focuses on toxic chemicals and as a result covers different chemicals than does the GHGRP. Some TRI chemicals are a result of combustion of fuels for energy (as most GHG emissions are), but others are used in and released from additional processes ranging from metal mining to surface cleaning. Analyzing toxic chemical releases reported to TRI and greenhouse gas emissions reported to the GHGRP together creates a more complete picture of emissions at the facility and industrial sector levels.
Note that in addition to differences in the chemicals reported to TRI and GHGRP, there are numerous other program differences including reporting thresholds. For TRI, the reporting threshold for most chemicals is 25,000 pounds manufactured or processed, or 10,000 pounds otherwise used per year, whereas for the GHGRP, the reporting threshold is based on emissions and is generally 25,000 metric tons of carbon dioxide equivalent per year.
This page was published in January 2017 and uses the 2015 TRI National Analysis dataset made public in TRI Explorer in October 2016.