On August 31, 2009, the U.S. Environmental Protection Agency (EPA) published a Notice of Data Availability, requesting public comment regarding its proposed "Federal Requirements Under the Underground Injection Control (UIC) Program for Carbon Dioxide (CO2) Geologic Sequestration (GS) Wells."   74 Fed. Reg. 44802 (Aug. 31, 2009) (Notice).  This update describes the Notice and generally explains EPA's proposed approach to regulate the underground injection of CO2.

What Is Carbon Capture and Sequestration?

Carbon capture and sequestration (CCS) is a term used to describe the process of capturing carbon dioxide emitted from industrial and energy-producing sources for the purpose of permanently storing it underground.  First, CO2 is captured from plant flue gas and other stationary CO2 sources and compressed into a fluid.  Liquid CO2 is then transported to the geologic sequestration site, usually by pipeline, and injected via wells into deep subsurface rock formations for long-term storage.  If the site is properly selected and monitored over time, the CO2 remains sequestered due to both physical and geochemical trapping processes. 

CCS is one approach that could reduce the amount of atmospheric CO2 in an effort to mitigate climate change.  Although underground injection of CO2 for enhanced oil and gas recovery is a long-standing practice, CCS is potentially much larger in scale and involves different technical issues; thus it requires significant investment in research and development, in addition to potentially requiring a new regulatory scheme.

EPA Regulation of Underground Injection of CO2

Geologic sequestration of CO2 through well injection meets the definition of "underground injection" in section 1421(d)(1) of the Safe Drinking Water Act, and EPA as well as states, territories and tribes with primacy to implement the UIC program act as co-regulators to protect underground sources of drinking water from any potential endangerment from underground injection of CO2.  Numerous factors potentially can increase the risk of contaminating underground sources of drinking water from GS projects, including improper siting, construction, operation and monitoring.

EPA and delegated states currently authorize injection wells associated with research and development projects as "Class V" wells.  EPA released Class V Experimental Technology Well Guidance for Pilot Geologic Sequestration Projects in March, 2007, which was intended to address only the experimental pilot projects anticipated to be brought online in advance of full-scale operations over the next several years.  

EPA also has been developing regulations to address permitting of such full-scale operations.  In July 2008, EPA published a proposed rule addressing UIC regulations specifically for CO2 GS wells.   73 Fed. Reg. 43492 (July 25, 2008).  In that rule, EPA proposed a new class of injection well (Class VI) along with technical criteria for permitting GS wells, including criteria for geologic site characterization, area of review and corrective action, well construction, operation, mechanical integrity testing, monitoring, well plugging, post-injection site care, and site closure.  EPA proposed that, in the absence of an aquifer exemption, the injection of CO2be confined to areas below the lowermost underground source of drinking water.  The July 2008 proposed rule was based on then-existing GS project experience, natural and industrial analogues, research and regulatory experience with underground injection.  Research in this field is continuing, however, and there currently are four commercial projects (in the Norwegian North Sea, Canada, Algeria and Norway) that also serve as an ongoing source of information. 

EPA's Notice of Data Availability

The Notice provides an update on newly available information and data related to research focused specifically on GS for long-term storage.  It also discusses the proposal to restrict injection to areas below the lowermost underground source of drinking water.    

First, the Notice contains preliminary field data from approximately 30 Department of Energy -sponsored Regional Carbon Sequestration Partnership projects, a number of which have either completed injection of CO2 or are in the process of injecting CO2.  The Notice summarizes select project activities and data generated from these pilot projects.  The Notice also describes the results of a Lawrence Berkeley National Laboratory (LBNL) study indicating that if injected CO2 comes into contact with shallow underground sources of drinking water, some trace element concentrations – particularly arsenic – could increase above drinking water regulatory standards.  A separate LBNL study suggests that basin-wide pressure influences from the underground injection of CO2 can be large and could push saline water upward into overlying aquifers in certain situations. 

Second, the Notice discusses EPA's July 2008 proposal to restrict GS of CO2 beneath the lowermost formation containing an underground source of drinking water.  EPA's proposal was based on the principle that placing distance between the injection formation and underground sources of drinking water decreases risks to drinking water sources.  EPA received numerous comments on that proposal, many of which stated that it was unnecessary, and that confining injection to below the lowermost underground source of drinking water may restrict the use of sequestration in areas of the country with deep underground sources of drinking water where well construction would be technically impractical or infeasible. 

EPA is now proposing to address those concerns by providing a waiver alternative for addressing injection depth in limited circumstances where there are deep underground sources of drinking water.  The proposed Class VI injection depth requirements would remain the same but would allow an owner or operator seeking to inject CO2 above or between underground sources of drinking water to apply for a waiver from those proposed injection depth requirements.  EPA believes that a waiver process affords flexibility to regulators and to owners and operators of GS projects to take site-specific factors into account.

Next Steps

The Notice does not contain any compliance requirements related to GS.  At this point, EPA is requesting comment from stakeholders on the studies, the advantages and possible disadvantages of a waiver process to the injection depth requirements and on current state activities addressing GS.

EPA will accept public comment on the Notice for 45 days.  EPA also will hold a public hearing regarding the Notice on September 17, 2009 at its Region V office in Chicago, Illinois.  Additional information regarding EPA's regulations may be found on EPA's website.