Is CCUS The Path to Net Zero?
Carbon capture, utilization, and sequestration (CCUS) offer a known and readily available method to reduce the net emissions of carbon dioxide and meet ambitious climate goals. The regulatory framework, and the multiple protections built into it, ensure that it is safe. However, as the number of requests for authorizations of CCUS projects increases, it is uncertain whether that very regulatory framework and the agencies in charge of permitting and regulating the injection of carbon dioxide will facilitate or inhibit our ability to meet those climate goals.
Upon rejoining the Paris Agreement on January 20, 2021, the United States announced ambitious climate goals: reduce greenhouse gas emissions 50-52 percent from 2005 levels by 2030, create a carbon-free power sector by 2035, and reach net-zero greenhouse gas emissions economy-wide by no later than 2050. The State of Louisiana, through the Governor’s Climate Initiatives Task Force, has also announced its own climate goals: reduce emissions 26-28 percent from 2005 levels by 2025; reduce emissions 40-50 percent from 2005 levels by 2030, and reach net-zero emissions by 2050.
The United States has already seen dramatic reductions in GHG emissions, due mostly to fuel switching from coal to natural gas in the power sector. Overall, EPA notes that GHG emissions (after accounting for sequestration from the land sector) dropped from 6,644.2 MMT CO2 eq. in 2005 to 5,215.6 MMT CO2 eq. in 2020, a decrease of 22 percent. GHG emissions from fossil fuel combustion dropped from 5,752 MMT CO2 eq. in 2005 to 4,334 MMT CO2 eq. in 2020, a decrease of 25 percent. There was a sharp decline of about 10 percent from 2019 to 2020, mainly due to decreased economic activity in 2020 due to COVID-19 restrictions.
The U.S. Energy Information Administration reports that fossil fuels (petroleum, natural gas, and coal) accounted for 79% of total U.S. energy consumption in 2020. Non-fossil fuel sources, such as renewables and nuclear, accounted for the balance. Overall, while EIA predicts that the amount of electricity generated from solar and wind will appreciably rise between now and 2050, it also notes that the use of fossil fuels will also rise to meet an ever-increasing demand.
Generally, CCUS involves the capture of carbon dioxide from fuel combustion or industrial processes and its subsequent use as a resource to create valuable products or its permanent storage deep underground in geological formations. Indeed, given that the use of fossil fuels may persist through 2050 and perhaps beyond, CCUS may be the only way to achieve net-zero by 2050. Regardless, CCUS is an available technology that can easily assist the US and Louisiana meet their climate goals.
EPA (or authorized states once the federal program is delegated to the state) regulate the underground injection of carbon dioxide as part of the Underground Injection Control (UIC) Program. Wells used for the injection and geologic sequestration of carbon dioxide are classified Class VI wells. The UIC Program has multiple regulatory safeguards in the permitting, construction, and operating of Class VI wells which serve to ensure the safe injection and sequestration of carbon dioxide.
First, a permit issued by EPA or the authorized state is required for the construction and operation of Class VI well. To obtain the permit, the applicant must submit a detailed application which must, among many other things, establish that there is a confining zone (that is, a layer of impermeable rock) between the area of injection and an underground source of drinking water (USDW) and that Class VI well will be constructed and operated in a manner that does not allow the movement of injected carbon dioxide into a USDW.
One major difference between Class VI wells and other classes of injection wells is the potential size of the “area of review.” In other wells, the area of review is a fixed distance from the well itself. But, in Class VI wells, the area of review is an area delineated using computational modeling which projects the extent of the lateral and vertical migration of the carbon dioxide plume and formation fluids in and through the subsurface.That modeled extent becomes the area of review. The applicant must perform corrective action on all wells within that modeled area of review to repair or fix deficient wells so that the movement of carbon dioxide into USDWs is prevented. Depending on the modeled size of the area of review and the number of deficient wells within that area of review, the costs of corrective action could be substantial.
Second, there are numerous construction requirements for Class VI wells. The surface casing must extend through the base of the lowermost USDW and then be cemented to the surface. The casing and cementing program must be designed to prevent the movement of fluids into or between USDWs. All materials used in construction must be designed for the life of the sequestration project and must be compatible with fluids with which the materials may be expected to come into contact. Then, the mechanical integrity of the well must be tested to determine if there is significant fluid movement into a USDW through channels adjacent to the injection wellbore.
Finally, there are many operating requirements protecting the USDW. The injection pressure may not exceed 90 percent of the fracture pressure of the injection zone to ensure that the injection does not initiate new fractures or propagate existing fractures in the injection zone.The operator must also prepare, maintain, and comply with a testing and monitoring plan which includes groundwater monitoring.
However, these requirements also provide multiple opportunities for regulatory agencies to over-regulate or otherwise inhibit the permitting and operation of Class VI wells. Obviously, the agencies must first ensure compliance with the Class VI rules to ensure that carbon dioxide remains properly sequestered. Nevertheless, experience with the UIC Program suggests that chronic understaffing slows the review of applications and creates a backlog of applications to be reviewed, which in turn reduces the number of permits issued.Further, narrow interpretations of the rules tend to restrict the number of fluids that can be injected. This may extend into the injection of carbon dioxide.For example, agencies have tended to calculate injection pressures in such a fashion as to lower them which in turn reduces the rate of injection and the number of fluids that may be injected.Injecting vast amounts of carbon dioxide will be necessary to meet the net-zero goal so artificially low injection pressures will impact our ability to meet that goal.
In short, CCUS can and should be an important part of the climate effort. The history of the UIC Program establishes that underground injection pursuant to the program is safe and the Class VI regulations continue those safeguards for the injection of carbon dioxide. However, permits need to be issued, wells constructed, and injection pressures properly set so that the net zero goal can be met by 2050, which is only a mere 28 years from now.