Q21. How did EPA develop the general threshold of 25,000 metric tons of carbon dioxide equivalent (mtCO2e) per year?

A21. EPA considered several factors when developing the reporting threshold, including the form of the threshold (e.g., emissions/year, potential to emit, capacity-based, facility or unit level).  EPA reviewed existing capacity-based (e.g., 25 megawatts) and emissions-based thresholds used in other GHG emissions programs (e.g., California’s 25,000 mtCO₂e) and the 10,000 mtCO₂e levels used in some voluntary programs, such as the Department of Energy’s (DOE’s) 1605b program.  Based on our review, EPA has determined that the selected 25,000 metric ton CO₂e threshold will cover many of the types of facilities and suppliers typically regulated under the CAA, while appropriately balancing emission coverage and burden.  EPA estimated that at a threshold of 25,000 metric tons of mtCO₂e/year, approximately 10,000 facilities and 85 percent of total GHG emissions will be covered.  At the 10,000 mtCO₂e/year level, EPA found that there would be a higher economic impact on small businesses including small industrial facilities and commercial buildings.