In response to readers emailing for more research on subsurface carbon storage, here are some additional resources.
The Big Sky Carbon Sequestration Partnership is undertaking a variety of research and testing projects. This is an international consortium of industry, national labs, universities and state agencies. Their FAQ discusses some of the issues and concerns:
Will Sequestered Carbon Dioxide Leak and How Can You Detect It If It Does? There is no guarantee that carbon dioxide sequestered in underground geologic formations wonâ€™t leak. However, in the petroleum producing areas of the United States, oil and gas deposits, as well as naturally occurring carbon dioxide gas, have been trapped underground for millions of years. With proper construction and monitoring, there is a very high probability that these same formations will also prevent the significant leakage of carbon dioxide. Sites will be chosen carefully, and only the ones with the best geology will be picked for projects. The U.S. is also fortunate to have lots of experience storing natural gas, in which gas is injected underground during the summer and then recovered to heat homes in the winter. That experience can be applied to carbon sequestration as well. Carbon dioxide is a much safer, non-combustible gas compared to natural gas, which is used for heating homes, cooking, and home water heating. By understanding where natural gas storage has been safe and successful, we can apply that knowledge to carbon sequestration.
The rock formations chosen for carbon sequestration will normally be more than 2,000 to 2,500 feet underground. There is, of course, the remote possibility of an undetected fracture in the rock that could allow carbon dioxide to migrate upward toward the surface. However, even if this did happen, movement is expected to happen slowly because it takes a long time to move through all the different layers of rock. There are two kinds of leaks to be concerned about: large, rapid leaks and small, slow leaks.
When carbon dioxide is injected into geologic formations, it is injected into porous rock, like sandstone using best engineering practices. There are a variety of tests and mapping activities that are used before injection to determine that a site is acceptable for injection. Such testing should reveal if there are fractures in the cap rock and other faults that could provide an avenue for more rapid escape. Even if these are in the formation, the carbon dioxide would first need to seep out of the formation into the fault before migrating to the surface. Therefore, scientists are reasonably certain that large rapid leaks will not be a problem when best engineering practices are used in carbon dioxide injection.
The oil and gas industry has extensive knowledge of monitoring leaks of various gases from their wells. We can use the same technology that has been used by the underground gas storage and petroleum industries for over 50 years to check on the integrity of stored carbon dioxide. There are several methods that are used together: 1) monitoring for changes in the gas pressure in the site â€“ a loss of pressure suggests a leak; 2) using â€œtracer gasesâ€ much like tracer bullets, that help scientists to detect where the gas is going; 3) looking for changes in soil composition that might suggest a leak; and, 4) using satellites designed to monitor for leaking gases. Modern engineering practices and the commercial experience of the oil and gas industry indicate that any significant leaks over a period of months, years, or decades are unlikely and that any such leaks that might occur can be managed so that they would not pose a significant risk to people or the environment.
This experience is less helpful in monitoring for small, slow leaks. There is some concern that such slow leaks could become a significant source of future atmospheric carbon dioxide loading over the course of a century. This is the subject of considerable ongoing research both to develop methods to monitor for such leaks and to mitigate those leaks if they occur.
The DOE Carbon Sequestration research program site is a source for links to initiatives and reports.
One apparently serious test was started in 2004 in Texas [by Lawrence Livermore Labs]:
“While we expect the plume to spread out over a few hundred meters, we expect the carbon dioxide to stay buried for thousands of years,” says Larry Myer, a geological engineer with the Earth Sciences Division who leads Berkeley Lab’s participation in this project. “The risk of leakage is a critical factor when storing carbon in brine formations but I’m optimistic that our test results will show that these formations are safe for carbon sequestration.”
While there’s little danger of a catastrophic escape, Myer says enough small leaks over time would negate the advantages of burying the carbon dioxide underground. Whether the carbon dioxide is buried underground or under the sea, something else has to be done with it other than venting it into the air. Two hundred plus years of industrialization have already resulted in the emission of an enormous amount of carbon dioxide into Earth’s atmosphere. According to a new report from the U.S. National Oceanic and Atmospheric Administration, record levels have been reached this year. NOAA scientists further predict that atmospheric carbon dioxide concentrations will double from pre-industrial levels by the middle of this century at the latest.
Although the effects of doubling atmospheric carbon dioxide levels are not entirely understood, most scientists believe there will be serious environmental consequences if steps are not taken to curb emissions. The goal of carbon sequestration is to prevent carbon dioxide emissions from reaching the atmosphere by capturing a significant amount of this greenhouse gas at the source, i.e., power plants and industrial smoke stacks, and securely storing it where no environmental harm will be done.
“We already have the technology base for storing carbon dioxide in brine formations because similar injections have been used in enhanced oil recovery operations for decades,” says Myer. “However, we need pilot tests to demonstrate that this approach to carbon sequestration is safe and effective.”
The bulletin Technology Options for the Near and Long Term from the U.S. Climate Change Technology Program summarizes R&D, with a brief recount of Recent Progress:
â€¢ Seismic methods are being used at the Sleipner test to map the location of the injected CO2 gas phase, but such methods are not capable of aiding mass balance over the long-term performance periods.
The Sleipner test refers to the Statoil North Sea test I mentioned in this previous post.
â€¢ Geophysical methods need to be developed to track supercritical CO2 in a diffuse (fingered) configuration that will be most typical of extended injection.
â€¢ Models, geophysical methods, and tracer indicators are being developed through the GEO-SEQ project.
â€¢ Development of innovative coatings for activated carbon particles within beads that may improve passive time-averaged sampling.
â€¢ Detection of CO2 emission from natural reservoirs has been investigated by researchers at the Colorado School of Mines, University of Utah, and the Utah Geological Survey, including attempting isotopic discrimination of biogenic CO2 from microbial respiration.
â€¢ Fundamental research on high-resolution seismic and electromagnetic imaging and on geochemical reactivity of high pCO2 fluids is ongoing in basic science programs.
â€¢ ORNL application of PFT tracer gases to Frio tests and NETL PFT testing at surface during injection (Frio
and New Mexico).
Another Lawrence Livermore Labs research project is based at the Rocky Mountain Oilfield Testing Center. Surprisingly, they need 100x more money:
LARGE-SCALE EXPERIMENTS IN THE FORM OF DEMONSTRATION PROJECTS ARE THE SINGLE MOST IMPORTANT NEED IN THE NEAR TERM. This effort will require a significant (10-100 fold increase!) in funding for geological carbon sequestration research through block grants and the DOE’s fossil fuel program. This need is urgent, and should be supported as a broad, bipartisan effort.