Carbon Capture and Storage in the States
Coal is one of the most abundant sources of energy for the United States. One quarter of the world’s coal reserves is found within the United States, and it provides nearly half of the electricity consumed by Americans. The U.S. Department of Energy (DOE) forecasts that coal will continue to dominate U.S. power generation for many decades to come. However, coal-fired power plants are responsible for the majority of greenhouse gas emissions (CO2) that come from the electric power sector—which produces 40 percent of the nation’s total. Since the U.S. EPA is beginning to regulate greenhouse gas emissions under the Clean Air Act, and many utilities are not eager to invest in coal plants due to uncertain costs, the prospects for new coal plants has been reduced. However, carbon capture and storage (or sequestration)—the process of capturing carbon dioxide (CO2) from power plants and storing it in geologic formations—could improve coal’s outlook significantly while reducing greenhouse gas emissions from coal.
How CCS Works
CCS begins by separating and capturing CO2 from power plant flue gas. There are three technologies for capturing CO2 that allow it to be captured before, during or after coal is burned. All three technologies are costly, require large amounts of energy and account for most of CCS’s added costs. For example, DOE’s National Energy Technology Laboratory (NETL) estimates that if current technology was used at a new coal power plant, the energy cost at the plant would increase by about 80 percent, although it also states there is the potential for these costs to decrease between 30 percent and 45 percent in the future.
Because current technologies are so expensive, many states provide financial incentives for CCS. Colorado, Florida, Indiana, Virginia, Kansas, Kentucky, Minnesota, New Mexico, North Dakota, New Mexico, New York, Ohio and Texas promote CCS through incentives such as tax exemptions, credits and deductions for advanced coal plants, technologies and equipment.
Carbon Capture Technologies
Pre-combustion applies to integrated gasification combined cycle (IGCC) power plants, where coal is converted into gas by applying heat under pressure in steam and oxygen. With this technique, the CO2 is removed before combustion takes place resulting in a relatively clean exhaust stream.
Post-combustion removes CO2 from flue gases at large point sources, such as power stations, after the coal is burned. This technique is primarily applicable to conventional power plants, but can also be applied to IGCC plants.
Oxy-fuel combustion captures the CO2 while burning coal in oxygen instead of air, which results in an almost pure carbon dioxide stream that is ready to be transported to the storage site. This technique can be applied to both new and existing coal-fired power plants, but the technology to cheaply and efficiently produce the needed oxygen has not yet been developed.
CCS Transportation and Storage
After CO2 is captured, it is compressed into a liquid state and transported to storage sites for injection. Because of the large amounts of CO2 that will need to be moved, pipelines will likely be used instead of ground transportation for shipping CO2 to storage sites. Storage sites are geologic formations chosen for their capacity to store CO2, the ability of CO2 to move within the formation, and how long the formation will be able to confine the CO2.
Louisiana, Montana, North Dakota, South Dakota and Texas have laws regarding transportation of CO2. Most of these states focus on fees for transporting CO2, integrity of pipelines and designating regulatory bodies for CO2 transportation.
Liability of Captured CO2
Although CO2 is considered to be a safe, non-toxic gas in low concentrations, it can be dangerous in confined or poorly ventilated areas. Since it is heavier than air, it remains low to the ground where it displaces oxygen. Parties shipping or storing CO2 are liable for harm that could arise from CO2 leaking out of pipelines or storage sites during injection and storage. This could include damage to the environment, human health, or drinking water. Because injection pipes hold the greatest risk for leaks, most states with liability laws hold the well operator liable during injection and then transfer liability to the state 10 to 15 years after the closure of the well.
Illinois, Kansas, Louisiana, Montana, North Dakota, Oklahoma, Pennsylvania, Texas and Wyoming have laws that address CO2 liability and ownership issues. Louisiana and Texas have set up trust funds for their carbon storage sites to pay for long-term regulation, monitoring and remediation.
Carbon capture and storage laws in 25 states pertain to issues such as CCS incentives, CO2 transportation, and liability and ownership of CO2. The U.S. Department of Energy’s National Energy Technology Laboratory (NETL) is helping to develop CCS projects by gathering data on possible geologic storage locations.
The federal government has provided significant funding for CCS. In 2009, the U.S. Department of Energy invested $3 billion to accelerate the development of carbon capture and storage to a commercial scale. Injection and storage of carbon dioxide continues to be examined by federal agencies, although most of the federal action has focused on transportation and storage. The U.S. Department of Transportation regulates CO2 pipeline operations under the Interstate Commerce Act and Hazardous Liquid Pipeline Act, while the Federal Energy Regulatory Commission (FERC) and the Surface Transportation Board regulate pipeline tariff rates and access.
In December 2010, a final rule was adopted making the U.S. Environmental Protection Agency the regulatory authority for underground injection and environmental monitoring of CO2 under the Safe Drinking Water Act.