FutureGen represents a technological advancement that integrates advanced coal gasification technology, the production of hydrogen from coal, electric power generation, carbon dioxide capture, and subsequent geologic storage. Carbon capture and sequestration (CCS) technology is an innovative method for reducing greenhouse gas emissions, but the new technology comes with added design and operational complexities and potential health, safety and environmental risks. Tetra Tech performed the human health and environmental risk assessments at the four candidate sites for the FutureGen Project and provided additional technical information for the Environmental Impact Statement (EIS) for the FutureGen Project. The risk assessment addressed the potential releases of captured gases at the power plant, during transportation via pipeline to the geologic storage site, and during subsurface storage. The focus of the analysis was on risk aspects that are specific to carbon sequestration.

The human health and ecological risk assessment included the following five major elements:

• Conceptual Site Models. Site-specific elements of the four sites were described in detail to provide the basis for the parameterization and analysis of likely human health and ecological exposure routes.

• Toxicity Data and Benchmark Concentration Effect Levels are summarized for all of the potentially complete exposure pathways, particularly for CO2 and H2S.

• The Pre-Injection Risk Assessment evaluates the potential risks associated with the plant and aboveground facilities for separating, compressing and transporting CO2 to the injection site.

• The Post-Injection Risk Assessment presented the analysis of potential impacts from the release of CO2 and H2S, after the injection of CO2 into subsurface reservoirs. An analog database was compiled that includes site characteristics at other CO2 storage locations and sites with natural CO2 accumulations and information on releases.

The results of both qualitative and quantitative analyses were used to identify uncertainties and to provide the basis for recommendations to address issues of concern and data gaps.