Demonstrates CO2 can be captured and stored in Gulf Coast saline formation

BY ROSE RAGSDALE FOR GREENING OF OIL

While the international debate rages on about capturing and storing carbon dioxide emissions from fossil fuel-fired power plants, researchers working in a worn out oil field in southwestern Mississippi have successfully sequestered more than 2 million metric tons of CO2 in 22 months.

The scientists, led by Dr. Susan Hovorka, a geological researcher from the University of Texas Austin, have joined a handful of research teams worldwide who have achieved this important milestone. In the process, they also moved the United States one step closer to meeting a goal recommended to the G-8 countries in 2008 by the International Energy Agency of launching 20 large-scale CCS demonstration projects globally by 2010, with a further goal of deploying the technologies by 2020.

The U.S. Department of Energy recently recognized the Phase III Early Test, conducted by the Southeast Regional Carbon Sequestration Partnership, or SECARB, for furthering carbon dioxide capture and storage technology and meeting the G-8 goals for deployment of 20 similar projects by 2020.

SECARB is one of seven regional partnerships that form a national network that DOE established across the United States to determine the best approaches for capturing and permanently storing gases that can contribute to global climate change. The networks have numerous stakeholders, including regulatory agencies and geological surveys; the Electric Power Research Institute; regional utilities; academic institutions; Native American enterprises; and the private sector.

SECARB is managed by the Southern States Energy Board, and its field activities are directed by the Gulf Coast Carbon Center of the Bureau of Economic Geology at the University of Texas at Austin. 

Top international carbon capture and storage, or CCS, projects

SECARB’s Early Test, which took place at the shut-in Cranfield oil field near Natchez, Miss., is the first project in the United States—the fifth worldwide—to monitor and document retention of CO2 injection volumes of at least 1 million metric tons.

The four other projects that hit 1 million metric tons of CO2 injected mark are the Sleipner and Snøhvit projects in Norway, Weyburn-Midale in Canada, and In Salah in Algeria.

In all, there are 192 proposed and active CCS projects in 20 countries and across five continents, according to NETL’s new Carbon Capture and Storage Database. Globally, the projects include 38 capture, 46 storage, and 108 for capture and storage. While most of the projects are still in the initial stages of planning and development, eight, including two in the United States, are actively capturing and injecting CO2.

However, NETL said the successes of the Cranfield project are likely to be replicated throughout the U.S. Gulf Coast region, since the geology of the Cranfield site is representative of other potential CO2 storage sites in this area.

“Successfully capturing and storing CO2 requires a more substantial effort than simply sliding a lid over its containment vessel. It demands intensive research to locate appropriate sites, then ongoing and meticulous monitoring and verification efforts after the CO2 is injected to make sure it stays put,” wrote DOE’s National Energy Technology Laboratory in a recent article. “So far, research efforts on the part of NETL scientists and their research partners have successfully located potential CO2 storage sites and demonstrated on small scales their reliability as storage units. But, the real test is a true-to-life, industry-scale demonstrations of capture and sequestration that will prove that the billions of tons of carbon emissions that billow forth from the world’s coal plants each year can be sequestered.”

Enhanced oil recovery, or EOR, drives big CCS projects

Like its contemporaries in Norway, Canada and Algeria, the Cranfield project combines CO2 storage with enhanced oil recovery—that is, injected CO2 is used to increase the amount of crude oil that can be extracted from otherwise depleted or hard-to-reach petroleum reservoirs. That’s because the high cost of carbon capture technology can be offset with profits from EOR projects.

CO2 enhanced oil recovery, or EOR, currently accounts for 4 percent of U.S. crude production, and DOE studies have indicated that CO2 EOR programs in favorable reservoirs like Cranfield and other large-scale geologic sequestration sites can boost domestic oil output significantly.

The “Early Test” at Cranfield is one part of SECARB’s two-step, large-volume injection test in the lower Tuscaloosa geologic formation in southeast Mississippi.

The second step or “Anthropogenic Test,” will annually inject 110,000 to 275,000 tons of CO2 captured from flue gas from a Southern Company power plant located near the injection site.

Monitoring of CO2 injection operations at Cranfield began in July 2008. The field was discovered in 1946 and abandoned in 1965 at the end of primary oil and gas production. Denbury Resources currently operates the field and is a partner in the study.

The work was expanded for phase 3 “Early Test” operations, and CO2 injection on a larger scale, in April 2009.

The source of the CO2 is naturally occurring pockets of the gas trapped in the subsurface formation known as the Jackson Dome.

The CO2 is transported by Denbury via pipeline to the injection site, where it will continue to be injected over several years. The volume of CO2 injected during the test so far has surpassed 2 million metric tons, Hovorka said June 7.

Southeast offers ample CCS capacity

Interim conclusions from the study at Cranfield were developed based on monitoring with standard and novel approaches for 30 months, research in five different areas, tests of soil gas approaches in complex environments, saturation change measured/monitored with multiple tools in complex flow field, first use of electrical resistance tomography in the United States for sequestration and quantification of dissolution, phase 3 of the project also will continue the work at Cranfield and initiate a CCS study involving the capture of CO2 from an “anthropogenic” or manmade source. The test is set to be conducted on or in proximity to a Southern Company plant site near the Gulf Coast in southern Alabama.

For this test, the site development design will be linked to the daily rate of delivered CO2. Captured volumes, from a Southern Co. power plant using a yet-to-be-determined CO2 capture method, are anticipated to range from 100,000-250,000 metric tons per year. CO2 injection is currently anticipated to begin in 2011 and continue until 2014.

SECARB also determined that the saline formations of the Gulf Coast are extensive and of regional significance as potential sinks for carbon sequestration. The lower Tuscaloosa Formation and similar Cretaceous-age formations are key components of a larger, regional group with similar geology called the Gulf Coast Wedge.

This wedge of sediments spans the entire region and includes the largest saline sinks (in terms of areal extent and capacity) for the SECARB region as well as the United States.

Massachusetts Institute of Technology estimates that annual stationary point-source emissions of CO2 are 1,047 million metric tons. Using the range of reported capacity, the Gulf Coast Wedge has the capacity to accommodate these emissions for about 300 to nearly 1,200 years, should 100 percent of this CO2 be captured and stored.

However, the likelihood of that much storage capacity being needed to resolve the problem of CO2 emissions from power plants that burn coal and other fossil fuels is doubtful, said Hovorka, who is principal investigator for the project.

“Personally, I don’t believe it is necessary or desirable to sequester all of our current CO2 emissions,” she said. “The cost of the CCS process will make other non-CO2 sources of energy such wind and solar more competitive, and it will incentivize the development of techniques for other energy production.”

Having said that, Hovorka added that she believes the geological formations in the southeastern United States, including the Gulf Coast Wedge, have enough capacity to sequester the CO2 emissions that will be required to be stored in the future.

Links of interest

Southeast Regional Carbon Sequestration Partnership

Gulf Coast Carbon Center

DOE Carbon Sequestration Research Program

Southern States Energy Board

Cooperative Research Centre for Greenhouse Gas Technologies

NETL Carbon Capture and Storage Database

Contact Rose Ragsdale at roseragsdale@live.com