Now in the early 21st century, research efforts of U.S. Department of Energy’s National Energy Technology Laboratory (DOE/NETL) scientists and their cohorts have made it possible to capture CO2 emissions from coal-based power sources, transport it, and safely and permanently store the greenhouse gas in large underground “vessels.” In fact, the successful results from NETL’s Carbon Capture and Storage (CCS) or Sequestration Program have paved the way for large-scale geologic sequestration demonstrations that enable the storage of 1-million tons of CO2 per year in underground geologic formations.
Taming the Wild Spirit
Making the most of our vast, domestic resources is imperative for America’s energy goals. Coal is the most plentiful fuel source in the United States, but it is also a major contributor to greenhouse gas emissions, particularly CO2. In fact, roughly one-third of U.S. carbon emissions comes from power plants and other large energy sources. Clean use of coal requires limiting how much of this greenhouse gas escapes back into the atmosphere, and, as Van Helmont observed, this spirit is tricky to contain.
A large, clay urn might have sufficed for Van Helmont’s preliminary discoveries, but to really address our current energy emissions situation requires vast, heavy-duty storage solutions. NETL scientists and their research partners have developed a CCS system that secures the carbon emissions from coal-fired power plants and then stores it permanently in underground geologic tanks, such as depleted oil and gas reservoirs, deep saline formations (porous rock saturated with saltwater), and unmineable coal beds. Oil and gas reservoirs have trapped crude oil or natural gas for millions of years by means of an impermeable, overlying caprock that forms a seal and traps the oil and gas. For CCS projects, this same mechanism securely holds CO2 for permanent storage in saline formations and depleted oil and gas formations. In unmineable coal beds, the CO2 is adsorbed on the coal and releases methane gas that can be recovered for use.
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. 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.
Now in its seventh year, DOE’s nationwide network of regional partnerships, the Regional Carbon Sequestration Partnerships (RCSP), is currently deploying projects in its Deployment Phase (Phase 3), and is taking on the large-scale tests and demonstrations that will allow us to keep using coal and to bury the most notorious byproduct associated with it.
The Big Picture
RCSP’s Deployment Phase (Phase 3) research brings the realization of the most promising carbon mitigation solution in reach (and in to view with the CCS database featured below). NETL’s latest CCS triumph is large-scale CCS, which means the capture and storage of more than 1 million tons of CO2 over the testing period. These large-scale projects are possible due to the successful outcomes of the first two phases, which “characterized” (Phase 1) and “validated” (Phase 2) the potential for sequestration. The goal of the deployment stage is to demonstrate large-volume injection of CO2 at a scale that mimics industry activity; these demonstrations will exhibit how large-scale CCS will make a large impact on the more than 30 billion tons of CO2 emitted per year worldwide.
While projects in the Validation Phase were designed to demonstrate that regional sequestration sites have the potential to store hundreds of years’ worth of CO2 emissions in the United States, the large-volume sequestration tests in the Deployment Phase will determine how CO2 storage sites will play out in real life. These tests will address practical issues, such as rates and pressures at which the CO2 can be pumped into the storage reservoir without fracturing the formation, well design, and how the reservoir will function over prolonged injection periods. Such issues can only be addressed by scaling up the size and duration of sequestration projects. Additionally, because each region possesses its own distinctive geologic formations and storage site characteristics, each site will yield valuable and unique operational information.
The most recent milestone occurred at the Cranfield site in southwestern Mississippi in collaboration with the Southeast Regional Carbon Sequestration Partnership. The DOE-sponsored storage project is one of only five sites worldwide to hold the distinction of having 1 million tons (or more) injected. However, 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.
Also succeeding to the 1-million tons injected stage are the Sleipner and Snøhvit projects in Norway, Weyburn-Midale in Canada, and In Salah in Algeria. All of these sites are NETL project partners:
- Sleipner—a saline formation project in which CO2 stripped from recovered natural gas is injected below the seabed in the North Sea.
- Snøhvit—CO2 from natural gas operations totaling over 700,000 tons per year is stored in saline formations in the North Sea.
- Weyburn-Midale—a United States-Canada dual effort where CO2 from North Dakota is piped to southeastern Saskatchewan and injected and stored in conjunction with commercial EOR.
- In Salah Gas Storage—CO2 from recovered natural gas is re-injected into a portion of the sandstone reservoir that produces natural gas.
A particular gem of the Cranfield project is that its CO2 storage is coupled with enhanced oil recovery (EOR)—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 stores. CO2 EOR currently accounts for 4 percent of the Nation's oil production, and DOE studies have indicated that a widespread CO2 EOR program in large, favorable reservoirs, like Cranfield and other large-scale geologic sequestration sites, can provide a significant contribution to domestic U.S. oil production.
The Works of Giants
Cranfield is currently the largest CCS project injecting CO2 in the United States, but several other RCSP projects are close at its heels. Following the route of Cranfield’s Deployment Phase success is a second wave of RCSP Phase 3 projects in queue:
- Midwest Geological Sequestration Consortium (MGSC)—MGSC will work with partner Archer Daniels Midland Company (ADM) to conduct a large-volume saline sequestration test at ADM’s ethanol-by-fermentation facility in Decatur, Ill. The test will inject 367,000 tons of CO2 per year for 3 years from the fermentation plant into the Mount Simon Sandstone, a major saline formation in the Illinois Basin.
- Plains CO2 Reduction Partnership (PCOR)—PCOR’s Fort Nelson project will store more than 1 million tons of CO2 per year captured from one of the largest gas processing plants in North America. The CO2 will be compressed and transported via pipeline to the target injection location, which is 3 miles from the gas plant, where it will be stored at a depth greater than 5,000 feet.
- Southeast Regional Carbon Sequestration Partnership (SECARB)—SECARB will conduct a two-step, large-volume injection test in the lower Tuscaloosa Formation in southeast Mississippi. The first step will inject 1.65 million tons of naturally occurring CO2 per year for 18 months. The second step, or “Anthropogenic Test,” will inject 110,000 to 275,000 tons of CO2 captured from flue gas from a Southern Company power plant located near the injection site. This injection rate will occur every year.
Additionally, Big Sky Carbon Sequestration Partnership, Midwest Regional Carbon Sequestration Partnership, Plains CO2 Reduction Partnership, Southwest Regional Partnership of Carbon Sequestration, and West Coast Regional Carbon Sequestration Partnership are all in various stages of site selection and project development. These preliminary stages will culminate in large-volume tests, similar to those mentioned above, that will span across the United States.
CCS technologies will not only allow the United States to continue to use fossil fuels in an environmentally responsible manner but, coupled with EOR, they also forge a path towards greater recovery of domestic oil, natural gas, and coal-bed methane. In addition, 20 small-scale CO2 injection field projects are either underway or completed in saline formations, oil and gas fields, and coals seams throughout the United States and Canada. All told, NETL’s CCS field projects, both geologic and terrestrial (preventing and removing CO2 from the atmosphere with plants, microorganisms in the soil, and terrestrial ecosystems) combined, are helping DOE reach goals to capture 90 percent of CO2 emissions with 99 percent storage permanence—and all of this with a less than 10 percent increase in the cost of energy.
A Storehouse of Information
While Van Helmont’s phantom gas was a wild spirit both elusive and invisible, NETL research has made it possible not only to capture and monitor CO2, but it has also made CCS projects and technologies more accessible than ever. The interested public can now monitor carbon sequestration progress alongside the professionals with the innovative CCS Database.
Interfaced with Google Earth, the NETL-developed database plots active and proposed CCS projects across the globe and delivers to the user’s fingertips a bird’s eye view of the various CCS projects underway worldwide. More than a map, the database is one-stop shopping for individuals interested in keeping tabs on the progress of the latest CCS projects. It displays information on developing technologies, site evaluation, estimated project costs, and anticipated completion dates. Clicking on a particular site prompts a pop-up data flag detailing the essentials, such as the amount of CO2 captured and injected daily and the particular capture technology in use.
CCS endeavors are identified by project support (whether DOE or Other) and project type (capture, storage, or capture and storage). A depot of up-to-date information on the efforts of the governments, groups, and industries involved, the database is continually updated as these entities move towards the successful deployment of CCS technology. Additionally, the pop-up data flag supplies a convenient link to the project webpage for anyone wishing to dig deeper into any particular sequestration venture.
The database presently catalogs 192 proposed and active CCS projects worldwide located in 20 countries and across 5 continents. 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. For a closer look, visit http://earth.google.com to download Google Earth, and click here for directions on launching the database.
Had Van Helmont access to the CCS database, one look at the whole host of CCS plot points would have made him coin his Gas a docile presence, rather than a wild spirit.