How Geothermal Energy Works – A Comprehensive Overview of the Process

How Geothermal Energy Works

The heat from the Earth’s core provides an abundant renewable energy source. This is a clean, green, and inexpensive form of power that reduces greenhouse gases and fossil fuel use.

The simplest geothermal power plants pull hot steam directly from underground reservoirs. The steam rotates a turbine, which activates a generator to produce electricity.

Dry Steam Plants

Geothermal energy is generated when hot water or steam rises to the surface through volcanoes, fumaroles, or geysers. Some of this naturally occurring heat is also found underground, where it’s pumped through pipelines under the ground to homes and businesses for heating purposes.

Geothermal electricity is produced when steam from the reservoirs is used to spin turbines, activating generators and producing power. The resulting mechanical energy is converted into electricity by transformers and then delivered to the electrical grid via transmission lines.

Flash Steam Plants

While solar panels and wind turbines have the spotlight in the renewable energy world, geothermal takes its quiet, behind-the-scenes approach to heating homes and powering businesses to another level. Geothermal energy, though more flashy and easy to visualize, is just as powerful and can play a crucial role in the energy industry’s future.

In a flash steam plant, extremely hot water is pumped from the ground under high pressure. When it reaches the surface, the pressure drops and the water turns into steam, which powers a turbine that spooks a generator to produce electricity. After the steam is used, it is pumped back underground, and the cycle begins again.

Geothermal energy can also be generated through a binary cycle plant. In a binary plant, moderately hot water is transferred via heat exchangers to an organic compound like isobutene (which boils at a lower temperature than water). This liquid fuels a turbine that spooks generating units and produces electricity.

Binary Cycle Plants

Many places on Earth have geothermal energy. Hot springs, for instance, are a thermal energy source used for bathing, heating homes, and more. They often contain silica and sulfur dioxide, two noxious gases that can cause environmental problems.

A geothermal power plant can take advantage of the same heat under the ground by using the force of vapor to turn a turbine that activates a generator and produces electricity. The cooled steam then condenses into water, and the cycle starts again.

Pressurized geothermal water passes through a heat exchanger and another fluid with a much lower boiling point in a binary-cycle plant. The organic working fluid vaporizes in the heat exchanger and drives a turbine to generate electricity. The cooled fluid is then returned to the heat exchanger to start the cycle. In this way, the fluid never contacts the atmosphere, and practically no emissions are released to the environment.

Geothermal Power Plants

Geothermal energy plants pull hot water or steam from reservoirs underground, use it to power turbines and generate electricity, and then return it as warm water. This process can be repeated many times a day.

Geothermal resources are abundant in some areas. People have long used these natural heat sources for bathing and heating homes.

Using the same technology, geothermal plants produce electricity by pumping water under high pressure as deep as two miles underground. When the water reaches the surface, it is heated by the ambient temperature of the area and turns to steam. This steam spins a turbine that powers a generator, sending the electricity to the electric grid. The steam then returns to its reservoir, which can be re-injected as new hot water or used in a geothermal heating system at your home.