FutureGen is the U.S. Department of Energy's (DOE) high-profile clean coal project. It 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 technology is an innovative method for reducing greenhouse gas (GHG) 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). The risk assessment addressed potential releases, including potential releases of captured gases at the power plant, during transportation via pipeline to the geologic storage site and during subsurface storage.

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

• Conceptual Site Models
• Toxicity Data and Concentration Effect Level summaries for the potentially complete exposure pathways, particularly for CO2 and H2S.
• A Pre-Injection Risk Assessment that evaluated the potential risks associated with the plant and aboveground facilities for separating, compressing, and transporting CO2 to the injection site
• A Post-Injection Risk Assessment that presented the analysis of potential impacts from the release of CO2 and H2S, after the injection of CO2 into subsurface reservoirs
• A Risk Screening and Performance Assessment that presented comparisons for each site of the results of both qualitative and quantitative analyses to appropriate criteria for CO2 and H2S.

Highlights:

• Determined potential risks for carbon separation units, pipelines, wellhead injection equipment, and releases from sequestration reservoir
• Used variety of air models to evaluate potential impacts of CO2 and H2S (SLAB, SCREEN3)
• Developed analog database of existing CO2 storage sites and natural accumulation sites