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PNNL Software Helps Greenhouse Gases Go Underground

The U.S. Environmental Protection Agency has established an agreement with PNNL to use Velo for the submission and evaluation of permits for geologic storage of carbon dioxide

December 2015
PNNL Software Helps Greenhouse Gases Go Underground
Carbon dioxide can be captured and injected in underground reservoirs deep in the Earth.

Carbon dioxide (CO2) emissions from large energy and industrial plants—such as fossil fuel-fired power plants—represent the largest source of greenhouse gas emissions. Though alternative energy resources are becoming available, the demand for electricity continues to grow, and effective methods for the capture and storage of CO2 are essential for the mitigation of greenhouse gas emissions. Geologic sequestration, or the injection of CO2 into subsurface reservoirs, is one solution.

To reduce emissions of greenhouse gases, CO2 can be captured from power plants or other industrial sources and then injected and stored deep in the Earth. These underground storage reservoirs often sit beneath drinking water resources. To protect underground resources, the Environmental Protection Agency (EPA) in November of 2010 established regulations for injection of CO2 for the purpose of geologic sequestration in a new class of underground injection wells; Class VI. Under the Class VI rule, operators, states, and land owners that wish to store CO2 underground can apply for a permit from the EPA. The EPA recently established an interagency agreement with PNNL to enhance the PNNL-developed collaborative data and knowledge management software framework, Velo, for their use in expediting the permitting process.

Permits on the Pronto

Without the software, the EPA faced the challenge of reviewing permit applications in a timely manner. They needed a streamlined, electronic data system to facilitate submissions and reporting and allow them to greatly improve collaboration and to shorten the time it takes for their permit review process. PNNL is developing software called the Geologic Sequestration Data Tool (GSDT) based on the Velo framework to provide EPA with a collaborative web browser-based tool for reporting, recordkeeping, and data management for all phases of a geologic sequestration project. The tool allows applicants to electronically submit a permit application, as well as all the required corresponding information needed for EPA to evaluate whether the project will comply with regulations and protect water resources.

EPA must follow very strict protocols during their permit application review. The GSDT will actively assist EPA with storage and tracking of documents, assigning roles and responsibilities to review team members, communications between EPA and the permit applicants, and tracking milestones to ensure timely review of a permit application.

EPA’s Use of STOMP-CO2 to Evaluate Models

A requirement of the Class VI rule is that applicants must use computational modeling to predict the size and shape of the plume that will form underground during CO2 injection. The EPA has chosen STOMP-CO2, a simulator developed at PNNL, as one of their software tools for independently verifying the modeling done by the applicants.

STOMP-CO2 is a member of the STOMP (Subsurface Transport Over Multiple Phases) suite of numerical simulators, which are used for a variety of environmental applications, hydrocarbon development, and geologic sequestration. EPA is using STOMP-CO2 on PNNL’s High Performance Institutional Computing (PIC) Cluster, providing EPA with access to sophisticated subsurface simulation capabilities that are equivalent to or better than those used by permit applicants.

Once a permit is granted, the operator of the project must provide EPA with periodic information to demonstrate they are operating in a safe manner and protecting underground sources of drinking water and human health. The injection process and well conditions must be continuously monitored, and periodic monitoring of the groundwater quality in the region above where the CO2 is being injected must be performed; all these data must be reported to the EPA.

In addition, the extent of the CO2 plume must be tracked over time; this information is used to periodically update the computational model. Geologic sequestration projects are often designed to inject CO2 for 20 or more years, and the EPA requires the site to be monitored for 50 years after injection has stopped. This adds up to a staggering amount of data and information reported to EPA during the lifetime of a geologic sequestration project. The GSDT allows EPA to responsibly manage the data and documents associated with these projects.

Velo has been recently used in a number of subsurface applications, including a Lawrence Berkeley National Laboratory-led international carbon sequestration modeling evaluation project called Sim-SEQ, and a PNNL-led geothermal energy code comparison project. In addition, several components of Velo are being considered for implementation in the National Energy Technology Laboratory-developed Energy Data eXchange (EDX) to support big data analysis for subsurface seismicity studies under the DOE Subsurface Technology and Engineering Research, Development, and Demonstration (SubTER) crosscutting initiative. It also is an integral part of the Advanced Simulation Capability for Environmental Management (ASCEM) user interface, Akuna.

PNNL Research Team: Gary Black, Chandrika Sivaramakrishnan, Sumit Purohit, Signe White, and Alain Bonneville

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