Types of Geothermal Power Plants

All geothermal power plants use high-temperature (300°F to 700°F) hydrothermal resources with both water and heat. It requires steam to turn large turbines that run electrical generators.

The Geysers geothermal area works with dry steam available below the ground that can be used directly in the steam turbines. Likewise, in some areas, super-hot water is turned to steam within the power plant to turn the turbines.

The basic requirements for geothermal resources to generate electricity are heat, fluid, and permeability. Now let’s have a look at the different types of geothermal power plants and how they work.

Production of Geothermal Energy

The history of geothermal energy began in Larderello, Italy, 1904. It was the first time when geothermal power was used to generate electricity. So how does it works?

Geothermal power plants and Geothermal heat pumps are two main ways of capturing and using this energy.

Geothermal Power Plant

The geothermal power plants use steam from reservoirs to generate electricity. There are three types of geothermal power plant technologies developed for converting hydrothermal fluids to electricity. They are dry steam, flash steam, and binary cycle. The type of geothermal power plant selected for use depends on the state and temperature of the fluid.

How Does a Geothermal Plant Work

These power plants are set in areas with geysers, hot springs, or volcanic activity to utilize the heat right below Earth’s surface. Here we’ll provide you a basic understanding of how a geothermal plant works:

  1. First, The wells of 1 or 2 miles deep are drilled to pump out the hot water or steam under high pressure.
  2. When the water reaches the surface, it is turned into steam with a drop in the pressure.
  3. This steam then spins a turbine connected directly to a generator producing electricity.
  4. Later, the steam is transformed back to the water state in a cooling tower.
  5. This cooled water is then sent back underground to begin the process again.

Types of Geothermal Power Plants

Here are the primary types of geothermal power plants

1. Direct Dry Steam

These power plants use steam directly from the reservoir to turn generator turbines. The drawn steam is directed towards a turbine/generator unit that triggers a generator to produce electricity.

The underground resources of steam in the U.S. are:

  • The Geysers in northern California, the world’s largest single geothermal source of electricity
  •  Yellowstone National Park in Wyoming, with a geyser known as Old Faithful

This steam power plant omits the need to transport and store fuels. It is one of the earliest types of geothermal power plants used at Lardarello in Italy, in 1904. These plants emit excess steam and a very less amount of gases. It is used even today, as it is very environment-friendly.

2. Flash and Double Flash Cycle

These power plants can be used with hydrothermal fluids above 360°F. It takes the pumped out high-pressure hot water from deep inside the ground and converts it to steam. This steam powers a turbine for generating electricity. All the leftover water or liquid can be flashed again, in a second tank (double flash). This allows you to extract even more energy.

3. Binary Cycle

These power plants work on the water with low temperatures of about 225°F to 360°F.  It transmits the heat from geothermal hot water to another working fluid. This fluid goes through a heat exchanger that vaporizes it and drives a turbine.

During the whole process, the water and secondary fluid are kept separate and it is a closed-loop. So, virtually nothing is emitted to the atmosphere. The two types of resources that can operate in a binary cycle power plants are:

  • Enhanced Geothermal Systems (EGS)

An enhanced geothermal system can tap into the geothermal resources that are hard to reach due to lack of water, rock type, or location. The U.S. Geological Survey estimates a potential of 500,000 megawatts of EGS resource is obtainable in the western U.S.

  • Low-temperature or Co-produced Resources

These geothermal resources are found at a temperature lower than or equal to 300°F. Low-temperature resources can be used to generate electricity while co-produced hot water comes as a byproduct of oil and gas wells and is being tested for its capabilities to generate electricity.

In the future, the most commonly used geothermal power plant will be binary plants.

Advantages and Disadvantages of Geothermal Power

Advantages Disadvantages
Environment-friendly Surface Instability
Highly-efficient Greenhouse emissions
Highly Sustainable Depletion of geothermal sources
Reliable Source of energy Requires a large amount of land
Low maintenance cost High investment cost

Is Geothermal Power Renewable?

An additional benefit of geothermal power is that it can replenish itself. So, you will not run out of it until the end of time. Its dependency on the water makes it renewable. The geothermal power is replenished by rainfall and the internal heat of the earth.

Final Words,

The extraction of geothermal energy with geothermal power plants comes with a lot of advantages. Using a power plant for converting hydrothermal fluids to electricity may bring you convenience, but you cannot ignore some major environmental concerns. Such as the release of hydrogen sulfide gas and the disposal of remaining geothermal fluids consisting of low levels of toxins.