Developments in geothermal energy in Mexico—part thirty-five. Direct contact and surface condensers in geothermal electric power plants

Abstract

At present, direct contact condensers are the most widely used type in geothermal plants around the world. They have technical and economic advantages over surface condensers. The latter are only used where there are environmental problems associated with the release of polluting gases to the atmosphere, principally hydrogen sulphide. The non-condensable gas chemistry is an important factor in the decision to select direct contact or surface condensers. When plant emissions are strictly limited, surface condensers are used. In the Cerro Prieto geothermal field a total capacity of 620 MW e has been installed. The field is in a large open valley with constant winds. This provides very good dispersion of the hydrogen sulphide released. However, further increases in installed capacity will need to incorporate control of hydrogen sulphide releases. Thus the Comisión Federal de Electricidad (CFE) has plans to build future plants with surface condensers and sulphur recovery systems.