This type requires a fluid temperature of at least 150o C and can use the turbine type of atmospheric (back-pressure) or condensing. Back-pressure type is simpler and cheaper. The dry steam that comes directly from the wells or from the flashing process in the separators for wet wells flowed into the turbine and then released into the air/ atmosphere as shown in the following figure.
With this type, the steam consumption (for the same inlet pressure) per generated kWh is nearly twice as the condensing type. Nevertheless, this type is very useful as pilot plants, stand-by plant, for isolated wells or for the generation of electricity for test wells during field development. This type is simple and relatively fast in the installation and generally available to the small size (2.5 to 5 MWe).
Condensing type has more additional equipment, more complex, larger size and requires a longer time (twice) for the construction and installation compared with the type of back-pressure. However, this type requires steam consumption which is approximately half of the type of back-pressure. In general, the capacity of condensing power plant type for one unit is 55-60 MWe, but today many power plants have capacity of 110 MWe.