Feasibility and Risk Study of a Geothermal Power Plant at the Salton Sea KGRA

This report contains the results of a feasibility and risk study performed by Bechtel National, Inc. and the Ben Holt Company under contract to the San Diego Gas and Electric Company (SDG&E). The purpose of the study was to define the most technically feasible and lowest cost near-term energy conversion process for a 50 MWe geothermal power plant at the Salton Sea known Geothermal Resource Area (KGRA). Using the latest information from the Geothermal This report contains the results of a feasibility and risk study performed by Bechtel National, Inc. and the Ben Holt Company under contract to the San Diego Gas and Electric Company (SDG&E). The purpose of the study was to define the most technically feasible and lowest cost near-term energy conversion process for a 50 MWe geothermal power plant at the Salton Sea known Geothermal Resource Area (KGRA). Using the latest information from the Geothermal Loop Experimental Facility (GLEF), which is currently in operation at the Salton Sea KGRA, conceptual designs, capital cost estimates, and busbar energy production cost estimates were developed for power plants employing several versions of flashed steam and flash binary energy conversion processes. A power plant and well field risk analysis was also performed. The results show that while the flashed steam plant has the advantage of lower plant capital cost, the brine flow rate required by the binary plant is lower. This results in busbar energy production costs for the two plants that are the same. However, the risk analysis indicates that the technical risks are less for the flashed steam further work at the GLEF. The version of the flashed steam process with lowest energy production cost was the dual-flash process with three 50 percent capacity trains of flash tanks with unmodified brine. Thus, it was determined that GLEF testing in the immediate future should be directed primarily toward this process. A series of GLEP tests and further studies were defined for the purpose of alleviating or minimizing the major risks associated with the flash steam process. The most important risks were found to be those associated with brine handling. They include producing the brine, carrying it through the plant, and injecting it into the subsurface formation. The report includes details of costs of a binary plant and a flash plant. [DJE-2005