Congress is considering policies to reduce U.S. emissions of greenhouse gases. Prominent among these policies are those promoting the capture and direct sequestration of carbon dioxide (CO 2 ) from manmade sources such as electric power plants and manufacturing facilities. Carbon capture and sequestration is of great interest because potentially large amounts of CO 2 produced by the industrial burning of fossil fuels could be sequestered. Although they are still under development, carbon capture technologies may be able to remove up to 95% of CO 2 emitted from an electric power plant or other industrial source. Carbon capture and sequestration (CCS) is a three-part process involving a CO 2 source facility, a long-term CO 2 sequestration site, and an intermediate mode of CO 2 transportation—typically pipelines. Some studies have been optimistic about pipeline requirements for CO 2 sequestration. They conclude that the pipeline technology is mature, and that most major CO 2 sources in the United States are, or will be, located near likely sequestration sites, so that large investments in CO 2 pipeline infrastructure will probably not be needed. Other studies express greater uncertainty about the required size and configuration of CCS pipeline networks. A handful of regionally-focused studies have concluded that CO 2 pipeline requirements for CO 2 sources could be substantial, and thus present a greater challenge for CCS than is commonly presumed, at least in parts of the United States. Divergent views on CO 2 pipeline requirements introduce significant uncertainty into overall CCS cost estimates and may complicate the federal role, if any, in CO 2 pipeline regulation. They are also a concern because uncertainty about CO 2 pipeline requirements may impede near-term capital investment in electricity generation, with important implications for power plant owners seeking to reduce their CO 2 emissions. In the 110 th Congress, there has been considerable debate on the capture and sequestration aspects of carbon sequestration, while there has been relatively less focus on transportation. Nonetheless, there is an increasing perception in Congress that a national CCS program could require the construction of a substantial network of interstate CO 2 pipelines. The Carbon Dioxide Pipeline Study Act of 2007 (S. 2144), introduced by Senator Norm Coleman and nine cosponsors on October 4, 2007, would require the Secretary of Energy to study the feasibility of constructing and operating such a network of CO 2 pipelines. The America's Climate Security Act of 2007 (S. 2191), introduced by Senator Joseph Lieberman and nine cosponsors on October 18, 2007, and reported out of the Senate Environment and Public Works Committee in amended form on December 5, 2007, contains similar provisions (Sec. 8003). The Carbon Capture and Storage Technology Act of 2007 (S. 2323), introduced by Senator John Kerry and one cosponsor on November 7, 2007, would require carbon sequestration projects authorized by the act to evaluate the most cost-efficient ways to integrate CO 2 sequestration, capture, and transportation (Sec. 3(b)(5)). The Energy Independence and Security Act of 2007 ( P.L. 110-140 ), signed by President Bush, as amended, on December 19, 2007, requires the Secretary of the Interior to recommend legislation to clarify the appropriate framework for issuing CO 2 pipeline rights-of-way on public land (Sec. 714(7)). This report examines key uncertainties in CO 2 pipeline requirements for CCS by contrasting hypothetical pipeline scenarios in one region of the United States. The report summarizes the key factors influencing CO 2 pipeline configuration for major power plants in the region, and illustrates how the viability of different sequestration sites may lead to enormous differences in pipeline costs. Power plants, particularly coal-fired plants, are the most likely initial candidates for CCS because they are predominantly large, single-point sources, and they contribute approximately one-third of U.S. CO 2 emissions from fossil fuels. The report discusses the implications of uncertain CO 2 pipeline requirements for CCS as they relate to evolving federal policies for carbon control. Under a national CCS policy, a key question is how to establish a CO 2 pipeline network at the lowest social and economic cost given the current locations of existing CO 2 source facilities and the locations of future sequestration sites. On its face, this may appear to be a straightforward analytic problem of the type regularly addressed in other network industries. The oil and gas industry, among others, employs myriad analytic techniques to identify and optimize potential routes for new fuel pipelines. In the context of CCS, however, predicting pipeline routes is more challenging because there is considerable uncertainty about the suitability of geological formations to sequester captured CO 2 and the proximity of suitable formations to specific sources of CO 2 . One recent analysis, for example, concluded that 77% of the total annual CO 2 captured from the major North American sources could be stored in reservoirs directly underlying these sources, and that an additional 18% could be stored within 100 miles of the original sources. Other analysts suggest that captured CO 2 may need to be sequestered, at least initially, in more centralized reservoirs to reduce potential risks associated with CO 2 leaks. They suggest that, given current uncertainty about the suitability of various on-site geological formations for long-term CO 2 sequestration, certain specific types of formations (e.g., saline aquifers) may be preferred as CO 2 repositories because they have adequate capacity and are most likely to retain sequestered CO 2 indefinitely. The Department of Energy estimates that the United States has enough capacity to store CO 2 for tens to hundreds of years. However, the large-scale CO 2 experiments needed to acquire detailed data about potential sequestration reservoirs have only just begun. Given current uncertainty about potential sequestration sites, policy discussions about CCS envision various possible scenarios for the development of a CO 2 pipeline network. If CO 2 can be sequestered near where it is produced then CO 2 pipelines might evolve in a decentralized way, with individual facilities developing direct pipeline connections to nearby sequestration sites largely independent of other companies' pipelines. The resulting network might then consist of many relatively short and unconnected pipelines with a small number of longer pipelines for facilities with no sequestration sites nearby. Alternatively, if only very large, centralized sequestration sites are permitted, the result might be a network of interconnected long distance pipelines, perhaps including high-capacity trunk lines serving a multitude of feeder pipelines from individual facilities. A third scenario envisions CO 2 sequestration, at least initially, at active oil fields where injection of CO 2 may be profitably employed for enhanced oil recovery (EOR). Indeed, a CO 2 pipeline network already exists for EOR purposes in the southwestern United States, although it is limited in geographic reach. Whether CCS policies ultimately lead to one or more of these scenarios remains to be seen; however, the configuration of the resulting CO 2 pipeline network, and its associated costs, may have a significant bearing on which CCS policies best serve the public interest. Infrastructure requirements and policy implications related to CO 2 pipelines become clearer when considering what actual pipeline projects might look like. This section outlines contrasting scenarios for hypothetical CO 2 pipeline development in the region covered by the Midwest Regional Carbon Sequestration Partnership (MRCSP). The MRCSP is one of seven regional partnerships of state agencies, universities, private companies, and non-governmental organizations established by the Department of Energy to assess CCS approaches. The MRCSP serves as a good illustration of CO 2 pipeline issues because it has a varied mix of CO 2 sources and potential geologic sequestration sites, and because geologists have completed a number of focused studies relevant to CCS in this region. The MRCSP has identified key CO 2 sources and geologic formations potentially suitable for carbon sequestration within its seven-state region encompassing northeast Indiana, Kentucky, Maryland, Michigan, Ohio, Pennsylvania, and West Virginia. Figure 1 shows the locations of 11 of the largest CO 2 sources located in the MRSCP region—all coal-fired electric power plants emitting over 9 million metric tons of CO 2 annually. There are numerous other CO 2 sources in this region, including many other power plants and large industrial facilities, but the 11 power plants in this analysis include the very largest in terms of annual CO 2 emissions. Figure 1 also shows the locations of the Rose Run sandstone, a deep saline formation identified by the MRCSP as a potential carbon sequestration site. As the figure shows, the plants all lie above or near to this formation, so suitable CO 2 injection sites presumably could be located very near to each of these plants. If the Rose Run formation proves to be viable for large-scale CO 2 sequestration, then some plants may be able to inject CO 2 directly below their facilities, and CCS pipeline requirements for some of the other 11 power plants could be small. If this were the case, then the CCS CO 2 pipeline network for the 11 plants might appear as shown in Figure 2 . The hypothetical pipeline layout in Figure 2 assumes that a 25-mile diameter, non-overlapping reserve area is needed for each plant's sequestration site and that any location within the Rose Run formation is viable for sequestration. Figure 2 also assumes that each power plant is either located at or is connected to the center of its respective sequestration field by a large trunk pipeline built along existing rights of way and capable of carrying its peak CO 2 output. Smaller pipelines branching from the centrally-located plant or from the trunk line distribute the CO 2 to multiple injection wells in the sequestration site. These smaller pipelines are not considered in detail in this report. Figure 2 shows that the longest trunk pipeline for CO 2 transportation is 32 miles long, and the average pipeline is approximately 11 miles long. According to models developed at Carnegie Mellon University (CMU), the capital costs to construct an 11-mile pipeline in the Midwestern United States with a capacity of 10 million tons of CO 2 annually would be approximately $6 million.