In December 2010, EPA amended the regulatory framework for the Greenhouse Gas Reporting Program to create Subpart RR, Geologic Sequestration of Carbon Dioxide. Under Subpart RR, facilities that conduct geologic sequestration by injecting CO2 for long-term containment in subsurface geologic formations are required to develop and implement an EPA-approved site-specific monitoring, reporting, and verification plan, and report basic information on CO2 received for injection, the amount of CO2 geologically sequestered using a mass balance approach and annual monitoring activities. This paper provides an overview of the Subpart RR greenhouse gas reporting requirements.


Geologic sequestration (GS) is the long-term containment of a carbon dioxide (CO2) stream in subsurface geologic formations and is a key component of a set of climate change mitigation technologies known as carbon dioxide capture and sequestration (CCS). CCS is a three-step process that includes capture and compression of CO2 from power plants or industrial sources; transport of the captured CO2 (usually in pipelines); and storage and monitoring of that CO2 in geologic formations, such as deep saline formations and oil and gas reservoirs. CCS could play an important role in achieving national and global greenhouse gas (GHG) reduction goals.

In December 2010, the U.S. Environmental Protection Agency (EPA) amended the regulatory framework for the GHG Reporting Program to create Subpart RR, Geologic Sequestration of Carbon Dioxide (EPA 2010c). EPA promulgated the rule under authorities provided in the Clean Air Act. The GHG Reporting Program, 40 CFR Part 98, requires reporting of GHG data and other relevant information from certain source categories in the United States. The purpose of the GHG Reporting Program is to collect accurate and timely GHG data to inform future policy decisions. Subpart PP of the GHG Reporting Program requires the reporting of CO2 supplied to the economy. During the public comment period on the Part 98 rule establishing that requirement, EPA received comments that CO2 geologically sequestered should be considered in the GHG Reporting Program. In the October 2009 final rule promulgating Subpart PP, EPA committed to taking action to collect such data in the near future (EPA 2009). EPA proposed GS reporting mechanisms on April 12, 2010 and finalized the rule on December 1, 2010, taking into account over 16,000 comments received during the 60-day public comment period. Data obtained under Subpart RR will, among other things, inform Agency decisions under the Clean Air Act related to the use of CCS for mitigating GHG emissions.

The rule establishing the Subpart RR GHG reporting requirements was closely coordinated with EPA's December 2010 Safe Drinking Water Act rule establishing Federal requirements under the Underground Injection Control (UIC) program for Class VI injection wells (EPA 2010a). The UIC program is designed to prevent the movement of such fluid into underground sources of drinking water (USDWs) by addressing the potential pathways through which injected fluids can migrate and potentially endanger USDWs. Subpart RR fulfills a separate but complementary goal, which is to quantify the amount of CO2 sequestered in geologic formations. EPA designed requirements under Subpart RR with careful consideration of UIC Class VI requirements to minimize overlap between the two programs.

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