« lessĪ thermodynamic analysis was performed in order to study the possibility of upgrading the thermodynamic performance of a direct-steam geothermal power plant through the use of a separating expander which produces work while achieving effective separation of the two phases. (5) Two-phase expanders in combination with steam turbines provide the highest output power. (4) Total flow machines, used alone, offer no performance advantage as compared to multi-stage direct flash steam, unless efficiency of total flow devices can be increased above current projections. (3) Multi-stage flash steam systems using steam turbines provide more output power than binary systems at all reservoir temperatures, using reasonable values for component performance. (2) Self-flowing stepped diameter wells provide more wellhead power than pumped wells (for equal production zone diameters) at nearly all reservoir conditions. The conclusions of this study are: (1) The flow rate from a self-flowing well can be substantially increased by increasing well bore diameter at and above the flashing level. Five conversion processes were compared with respect to fraction of available power converted to electric power: flash steam (steam turbines operating on steam from flash vaporization of the brine), dual steam (flash steam with two-phase expanders to recover the flash vaporization mechanical energy), total flow (two-phase expanders only), binary (heat transferred from the brine to a secondary working fluid), and flash more » binary (heat transferred from flashed steam to a secondary working fluid). Two brine production methods were compared with respect to available power at the wellhead: self flowing (brine lifted by steam from vaporization of the brine), and pumped (brine lifted by a mechanical pump and kept in the liquid state). A comprehensive list of references is provided for the reader who wishes to make an in-depth study of any of the topics mentioned. Technical data is presented in twenty-two tables forty-one figures, including eleven photographs, are also included to illustrate the text. Plans for future usage of geothermal energy are described for the above-mentioned countries and the following additional ones: the Azores (Portugal), Chile, Costa Rica, Guatemala, Honduras, Indonesia, Kenya, Nicaragua, and Panama. In some cases the economics of power generation are also presented. In each case, the geological setting is outlined, the geothermal fluid characteristics are given, the gathering system, energy conversion system, more » and fluid disposal method are described, and the environmental impact is discussed. Existing geothermal plants in the following countries are covered: China, El Salvador, Iceland, Italy, Japan, Mexico, New Zealand, the Philippines, Turkey, the Union of Soviet Socialist Republics, and the United States. Power plant performance and operating factors are defined and discussed. An introduction is given to various types of energy conversion systems for use with geothermal resouces.

This report constitutes a consolidation and a condensation of several individual topical reports dealing with the geothermal electric power stations around the world.

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