| Abstract |
Deep direct-use (DDU) geothermal energy was assessed for its feasibility as a thermal energy source in agricultural research facilities at the University of Illinois at Urbana-Champaign (UIUC) campus. This district-scale heating and cooling source will exploit the Illinois Basin, a low-temperature sedimentary basin with multiple potential sources of geothermal energy, including the St. Peter Sandstone and Mt. Simon Sandstone. DDU geothermal energy systems are believed to provide lower-emission alternatives compared to traditional heating and cooling methods; however, low-temperature, high-salinity DDU heat sources are less-frequently utilized. The primary objective of this project is to investigate the feasibility of implementing a geothermal heat recovery complex on the UIUC campus. A number of system characteristics are investigated, including heat-extraction performance, heat-deployment methods, well design alternatives, challenges of design commercialization, levelized cost of heat, and life cycle environmental impacts. The work in this paper focuses on a life cycle assessment (LCA) to quantify the overall environmental impacts and co-benefits of the system. The LCA was performed using a spreadsheet tool that was simultaneously developed to provide insight into the cradle-to-grave environmental impacts associated with the proposed geothermal system, as well as other deep direct-use systems with similar objectives. This tool allows for a more in-depth analysis of the feasibility of DDU systems with respect to the overall environmental impacts of the system. The impact categories that were evaluated within this LCA tool are ozone depletion, global warming potential (GWP), smog, acidification, eutrophication, and fossil fuel depletion. As an example of the environmental LCA results, with respect to the GWP category, if facilities in the agricultural research corridor at UIUC were heated through the use of the proposed DDU system, the GWP emissions associated with the use of traditional fuels such as propane and natural gas could be offset in approximately 10 years of operation. |