Geothermal Power Plants

One very promising use of geothermal power is the generation of electricity with geothermal power plants. Areas with hot geothermal reservoirs can use this heat and steam to create electricity without having to spend money for fuel and without polluting the atmosphere or ground.

Geothermal power plants have much in common with traditional power-generating stations. They use many of the same components, including turbines, generators, heat exchangers, and other standard powergenerating equipment. All geothermal power plants use geothermal steam to turn a turbine. The turbine is attached to a generator that creates the electricity which is fed into a grid leading to individual users. See our animation below.

Every geothermal site has its own unique set of characteristics and operating conditions. For example, the fluid produced from a geothermal well can be steam, brine, or a mixture of the two; and the temperature and pressure of the resource can vary substantially from site to site. The chemical composition of the resource can contain dissolved minerals, gases, and other hard-to-manage substances. Geothermal power plants are designed to optimize power generation by taking these site-specific conditions into account.

Types of geothermal power plants:

There are four main types of geothermal power plants:
• Flash Steam Power Plants have reservoirs with water between 300 and 700 F (148 and 371 C). This water comes up from the well and is flashed (turned quickly) into steam, which powers a turbine.

• Binary cycle power plants have reservoirs with water between 250 and 360 F (121 and 182 C), which is not quite hot enough to generate enough steam to power a turbine. These plants use the heat from the water to heat another liquid with a lower boiling temperature, called a binary liquid. The binary liquid boils and produces steam to spin a turbine.

• Dry steam power plants have reservoirs that produce steam but not water. The steam is piped directly into the plant, where it spins a turbine.

• Hybrid or Enhanced power plants that combine geothermal heat with other sources of energy, such as methane.

All types of geothermal power plants have no emissions and can produce a large amount of power. Geothermal power is especially appealing because it is possible to have power plants of almost any size, from tiny 100 kilowatt plants to much larger 100 megawatt plants that are connected to national power grids. They can operate twentyfour hours a day every day of the year, but they can also vary operation according to demand.

 

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