Heber Geothermal Project, binary-cycle demonstration plant. Volume II. Proposal abstract

San Diego Gas and Electric (SDG and E) believes that the binary-cycle offers an improved method of converting moderate temperature geothermal resources into electric power. The process, shown schematically in figure 1-1, has significant advantages over existing methods of geothermal power generation. The advantages of the binary process are that greater amounts of power can be generated from a given resource, fewer wells are needed to support a given power output, and the binary-cycle is expected to be more economical than the flash process for this type of resource. Another advantage is that the binary-cycle is a closed process and thus enhances environmental acceptability. In addition, this process is applicable to a larger range of the nations geothermal reservoirs. It is estimated that 80% of the nation's hydrothermal resources can be classified as moderate temperature (300 to 410 F) resources. The flash process, commonly used to convert high temperature geothermal resources to electric power, is technically feasible for moderate temperature resources. However, when compared to the binary process for moderate temperature applications, the flash process conversion efficiency is lower, environmental impacts may require abatement, and power production costs may not be commercially competitive