This three-year project—performed by faculty and researchers from Columbia University—will develop an injection system for tagging CO2 with carbon 14 (14C) at an atmospheric level (1 part per trillion) and measuring the radioactivity in collected samples. Such tagging of injected CO2 will lead to quantitative monitoring of CO2 and make it possible to accurately inventory geologically stored carbon. The systems will be tested in the laboratory and at the CarbFix demonstration project in Iceland, where CO2 is injected into a permeable basalt formation at 1,970 feet in depth. Once the technology is proven, adoption of this system will provide a quantitative methodology to verify the amount of CO2 stored, thereby increasing confidence in geologic storage.
Through its core research and development program administered by the National Energy Technology Laboratory (NETL), the U.S. Department of Energy (DOE) emphasizes monitoring, verification, and accounting (MVA), as well as computer simulation and risk assessment, of possible carbon dioxide (CO2) leakage at CO2 geologic storage sites. MVA efforts focus on the development and deployment of technologies that can provide an accurate accounting of stored CO2, with a high level of confidence that the CO2 will remain stored underground permanently. Effective application of these MVA technologies will ensure the safety of geologic storage projects with respect to both human health and the environment, and can provide the basis for establishing carbon credit trading markets for geologically storing CO2. Computer simulation can be used to estimate CO2 plume and pressure movement within the storage formation as well as aid in determining safe operational parameters; results from computer simulations can be used to refine and update a given site’s MVA plan. Risk assessment research focuses on identifying and quantifying potential risks to humans and the environment associated with geologic storage of CO2, and helping to ensure that these risks remain low.
It will be necessary to improve existing monitoring technologies, develop novel systems, and protocols to satisfy regulations to track the fate of subsurface CO2 and quantify any emissions from reservoirs. The Carbon Storage Program is sponsoring the development of technologies and protocols by 2020 that are broadly applicable in different geologic storage classes and have sufficient accuracy to account for greater than 99 percent of all injected CO2. If necessary, the tools will support project developers to help quantify emissions from carbon capture, utilization, and storage (CCUS) projects in the unlikely event that CO2 migrates out of the injection zone. Finally, coupled with our increased understanding of these systems and reservoir models, MVA tools will help in the development of one of DOE’s goals to quantify storage capacity within ± 30 percent accuracy.
The development of a quantitative inventory tool using 14C for tagging geologic storage of CO2 is expected to result in a true inventory of human injected and stored CO2 in geologic reservoirs. In combination with conventional monitoring technologies, it will significantly improve the overall resolution of monitoring CO2 storage operations and will contribute to verification of leakage at the surface. If the CO2 tagging technology is successful, it will provide another tool that can validate that the carbon dioxide has been effectively stored in the geologic formation, thereby helping to increase confidence in geologic storage.
The primary objective of the DOE’s Carbon Storage Program is to develop technologies to safely and permanently store CO2 and reduce Greenhouse Gas (GHG) emissions without adversely affecting energy use or hindering economic growth. The Programmatic goals of Carbon Storage research are: (1) estimating CO2 storage capacity in geologic formations; (2) demonstrating that 99 percent of injected CO2 remains in the injection zone(s); (3) improving efficiency of storage operations; and (4) developing Best Practices Manuals (BPMs).
The overall goal of this project is to generate a CO2 accounting and verification technology that helps foster public trust in the safety and permanence of CO2 storage (Figure 1). A direct method of quantitative accounting is to tag the injected high-flow stream of injected CO2 with a tracer of 14C at a concentration similar to the natural 14C level in the atmosphere. Because fossil fuels (from which CO2 is generated through combustion for the purpose of energy production) and geologic formations at depth contain negligible amounts of 14C, this tracer is an extremely sensitive and likely effective, tag for human injected carbon. This goal will help evaluate and demonstrate CO2 storage permanence. Specific project tasks and objectives toward the overall goal of this project include:
Design of the 14C tagging microcartridge injection systems and filling stations for tracer injection: This effort includes designing and fabricating microcartridge systems that can hold either dissolved or pure compressed tracer gas (SF6 and 14CO2). These microcartridges will be designed to inject tracer gases at the 1 part per trillion (ppt) levels. Accompanying filling stations will also be designed and fabricated.
Laboratory-scale evaluation of injection systems: Designing and constructing a high-pressure flow system for mixing. At the Lamont-Doherty radioisotope laboratory, test the injection systems, first with SF6 and later with 14CO2, to demonstrate the controlled tracer injection (1 ppt) into water, liquid CO2, or supercritical CO2 (flow rate of 1 kg/s).
Development of 14CO2 detection system: Develop an improved 14C detection system. Current monitoring equipment for 14C activity is designed for other applications, but can be streamlined and improved for project purposes.
Field tests of developed 14CO2 tagging systems: The CarbFix demonstration project in Iceland offers an excellent opportunity to test the tagging system, with measurements to be verified by conventional 14C detection methods.
Hazard and environmental analyses: Perform a life cycle analysis of the full 14C cycle in the proposed MVA protocol, addressing pertinent hazard and environmental concerns in order to ensure the safety of this MVA method.
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