Electrical Production From Moderate Temperature Geothermal Brines

Direct contact binary cycles may be used to develop electrical power from moderate temperature geothermal brines. For a simple Rankine cycle using direct contact heat exchangers isobutane is preferred as a working fluid for brines at temperatures greater than 138°C. Pentane appears more attractive at lower temperatures. For all moderate temperature application, however, the use of bottoming cycles, multi-turbine, multi-fluid cycles, yields significantly better performance.