全球地热资源分布图

Earth’s crust is broken into huge plates that move apart or push together at about the rate our fingernails grow. Convection of semi-molten rock in the upper mantle helps drive plate tectonics.

地热电厂
Natural steam from the production wells power the turbine generator. The steam is condensed by evaporation in the cooling tower and pumped down an injection well to sustain production.

地热电厂发动机组：早期的类型

地热发电机组：干蒸汽式
In dry steam power plants, the steam (and no water) shoots up the wells and is passed through a rock catcher (not shown) and then directly into the turbine. Dry steam fields are rare.

The first geothermal power plants in the U.S. were built in 1962 at The Geysers dry steam field, in northern California. It is still the largest producing geothermal field in the world.

The first modern geothermal power plants were also built in Lardello, Italy. They were destroyed in World War II and rebuilt. Today after 90 years, the Lardello field is still producing.
20 plants are still operating at The Geysers. Wastewater from nearby cities is injected into the field, providing environmentally safe disposal and increased steam to power plants.

地热发电机组：闪蒸式
Flash steam power plants use hot water reservoirs. In flash plants, as hot water is released from the pressure of the deep reservoir in a flash tank, some if it flashes to steam.
Flash technology was invented in New Zealand. Flash steam plants are the most common, since most reservoirs are hot water reservoirs. This flash steam plant is in East Mesa, California.

This flash plant is in Japan. In flash plants, both the unused geothermal water and condensed steam are injected back into the periphery of the reservoir to sustain the life of the reservoir.
This plant operates in the middle of crops in the Imperial Valley, California. High mineral contents of some southern California geothermal reservoirs provide salable byproducts like silica and zinc.

地热发电机组：二元介质式
In a binary cycle power plant (binary means two), the heat from geothermal water is used to vaporize a "working fluid" in separate adjacent pipes. The vapor, like steam, powers the turbine generator.
In the heat exchanger, heat is transferred from the geothermal water to a second liquid. The geothermal water is never exposed to the air and is injected back into the periphery of the reservoir.

In the heat exchanger, heat is transferred from the geothermal water to a second liquid. The geothermal water is never exposed to the air and is injected back into the periphery of the reservoir.
This power plant provides about 25% of the electricity used on the Big Island of Hawaii. It is a hybrid binary and flash plant.