How Geothermal Power Plants Provide Clean Energy

What are some of the different ways to generate electricity from geothermal fluids? Read on to find out!
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What Are The Different Types Of Geothermal Power Production?

We recently used this space to look at the variety of ways that geothermal energy can be utilized. Today, let's hone in specifically on geothermal power production and look at the different ways that electricity can be generated from geothermal energy.

There are primarily three types of geothermal power plants: dry steam, flash steam, and binary cycle. Each of them uses hot water, steam, or a combination of the two to create power.

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Velika Ciglena geothermal power plant in Bjelovar, Croatia. Photo credit: Joseph Bonafin
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Velika Ciglena binary cycle geothermal power plant in Bjelovar, Croatia (Photo credit: Joseph Bonafin, 2019 GRC Photo Contest entry)
Dry Steam Geothermal Power Plants

Dry steam power plants use steam from underground to operate a turbine, which produces power. Dry steam plants were the earliest type of geothermal power plants built, the first of which was built in Larderello, Italy in 1904.

You can see dry steam power production in action at The Geysers in California. The Geysers are the world’s largest single source of geothermal power.

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Figure demonstrating the functionin of a dry steam geothermal power plant
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Figure taken from "A Guide to Geothermal Energy and the Environment", Geothermal Energy Association, 2007.
Flash Steam Geothermal Power Plants

Flash steam power plants are the most common type of geothermal power plants in use today. Hot water (ranging from 360°-700°F) is pressurized at high levels and pumped from the earth into a tank at the surface with much lower pressure. When the pressure is reduced, it causes the water to turn to steam, or "flash". This steam drives the turbine, which produces power.

Flash steam plants come in single, double and triple varieties, denoting the number of times the water is "flashed" into steam.

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Figure demonstrating functionality of a flash steam geothermal plant.
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Figure taken from "A Guide to Geothermal Energy and the Environment", Geothermal Energy Association, 2007.
Binary Geothermal Power Plants

In a binary power plant, pressurized hot water (below 400°F ) passes through a heat exchanger along with a second fluid (hence, the term binary) that has a much lower boiling point. This causes the second fluid to "flash" into vapor, which drives the turbine and generates electricity.

This type of power plant is considered a closed loop system because almost nothing except water vapor is emitted into the atmosphere. Because it’s such a clean source of energy, much of the geothermal electricity in the future could come from binary power plants. In fact, the vast majority of new geothermal plants in the U.S. since the year 2000 have been binary cycle plants.

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Figure demonstrating functionality of a binary cycle geothermal power plant.
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Figure taken from "A Guide to Geothermal Energy and the Environment", Geothermal Energy Association, 2007.