CARBON SEQUESTRATION OPTIONS IN THE OHIO RIVER VALLEY

Carbon sequestration, also referred to as CO2 capture and storage (CCS), is one option in a portfolio of mitigation actions for stabilizing atmospheric CO2. CCS consists of separation of CO2 from industrial and energy-related sources, transport to a storage location, and long-term isolation from the atmosphere. In this study, I analyzed ways to match CO2 emissions from coal-fired electricity generation plants in the Ohio River Valley with suitable geologic sinks.

This region was selected because of its large fleet of coal-fired power plants, apparent potential for significant subsurface sequestration capacity, and possible options for utility collaboration in transport and storage. Deep saline aquifers, the largest potential geologic sinks, were the focus of the analysis. The estimated reservoir capacity of deep saline reservoirs in the region is approximately 118 Gt of CO2. Current CO2 emissions for the Midwest region are approximately 800 Mt of CO2 annually, with much of the emissions coming from large coal-fired power plants.

My preliminary results show that it is impractical sequester CO2 in the near proximity of each power plant. To develop a CCS on a large scale, a regional approach is necessary. I then examined options for using large reservoirs that are shared by multiple sources of CO2. Employing large regional reservoirs allows for pooling of resources for geologic characterization, post-injection monitoring, and infrastructure costs. Shared reservoirs also help to clarify subsurface property rights and contain possible liability. Field unitization in the oil and gas industry served as a model.

I found that deep saline aquifers are not yet sufficiently characterized for large-scale injection of CO2. The sequestration potential of deep saline aquifers in the Appalachian Basin, which lies under most of the power plants in the region, was compared to the larger but more distant aquifers of the Mt. Simon formation, which would require a more extensive pipeline infrastructure for CO2 transport. Further results from test wells and pilot injection projects are needed to determine the exact roles that these deep saline reservoirs will play in CCS in the Ohio Valley.