Among the renewable energy sources available today, geothermal energy is one of the most common ones. It is the heat derived within the subsurface of the earth, and it is carried to the earth’s surface by water and/or steam.
Geothermal energy is widely used for heating and cooling purposes or can be harnessed to produce clean electricity. Well, in this reading, we’ll explore what geothermal energy is, its applications, diagram, and how it works. We’ll also explore its advantages and disadvantages.
Let’s get started!
What Is Geothermal Energy?
Geothermal energy is thermal energy generated and stored in the earth. The word ‘geothermal’ has Greek roots with γη (geo), meaning earth, and θερμος (thermos), meaning hot.
It is renewable energy derived within the sub-surface of the earth and transported with water and/or steam to the earth’s surface. Thermal energy is the energy that determines the temperature of matter. Thus, it is known as thermal energy.
The geothermal energy of the earth’s crust originates from the original formation of the planet and from radioactive decay of materials and continual heat loss from the earth’s formation.
Furthermore, geothermal energy is a form of energy conversion in which heat energy from within the earth is obtained and harnessed for cooking, bathing, space heating, electrical power generation, and many more uses.
In a brief history of geothermal energy, it has been proven that native Americans used geothermal energy for cooking as early as 10,000 years ago.
In ancient times, baths heated by hot springs were used by the Greeks and Romans. And as for space heating, the Roman city of Pompeii during the 1st century CE used geothermal energy. it was initially limited to sites where hot water and steam were accessible.
Applications of Geothermal Energy
The use of geothermal energy is common in over 20 countries. The United States is recorded as the largest producer of geothermal energy in the world.
They have hosted the largest geothermal field known as the Geysers in California. The field is spread over 117 square kilometers and formed over 22 power plants, with an installed capacity of over 1.5 GW.
Iceland has also made good use of geothermal energy since 1907, describing itself as a ‘pioneer’ of geothermal power. Over 25% of energy is produced from five geothermal power plants.
They were successful due to the 600 hot springs and 200 volcanoes in the country. The applications of geothermal energy can be divided into three categories: direct use, geothermal heat pumps, and electric power generation.
Related: What is Thermal Energy? its Examples and How it is Produced
Direct Uses of GeoThermal Energy
The direct uses of geothermal energy involve the use of heated water from the ground without the need for any other heating source. The direct of geothermal resources is at low temperature, which ranges from about 50 to 150 0C (122 and 302 °F).
Low-temperature geothermal water and steam have been used to warm single buildings and whole districts where numerous buildings are heated from a central supply source. Also, most swimming pools, greenhouses, balneological (therapeutic) facilities at spas, and aquaculture ponds have been heated with geothermal resources.
Other common applications of direct uses of geothermal energy include cooking, industrial uses such as drying fruits, vegetables, and timber, milk pasteurization, and large-scale snow melting.
Geothermal Heat Pumps
Geothermal heat pumps (GHPs) are used to heat buildings in the winter and cool them in the summer. They took advantage of the relatively stable moderate temperature conditions that are obtained within the first 300 meters (1000 feet) of the surface.
Most GHP temperatures are found at shallower depths, such as 6 meters (about 20 feet) of the earth’s surface. Consequently, the heat can be used to warm buildings during winter, when the air temperature falls below that of the ground.
Similarly, during summer, warm air is drawn from a building and circulated underground, where it loses much of its heat and is returned.
Electrical Power Generation
Geothermal energy is used to generate electricity based on the temperature and the fluid (steam) flow. Electricity is produced in three ways in geothermal power plants.
These three different designs control the behavior that is used to drive electrical generators. The excess water vapor produced at the end of each process is condensed and returned to the ground, where it is reheated for later use.
This is why geothermal power is considered a form of renewable energy.
Diagram
Types of GeoThermal Energy Plant
Geothermal power plants come in three different types: dry steam, flash, and binary.
Dry Steam
The dry steam design takes steam directly from fractures in the ground to drive a turbine. The heated water vapor is funneled directly into a turbine that drives an electrical generator.
Flash Plants
The flash plant pulls high-pressure hot water from underground and mixes it with cooler, low-pressure water. This, in turn, creates steam that is used to drive a turbine.
Pressurized high-temperature water is drawn from beneath the surface into containers at the surface known as flash tanks. This is where the sudden decrease in pressure causes the liquid water to flash or vaporize into steam.
The flash is then used to power the turbine-generator set. Finally,
Binary-Cycle
The binary-cycle power plants employ stem driven off a secondary working fluid such as ammonia and hydrocarbon contained within a closed loop of pipes to power the turbine-generator set.
In this process, geothermally heated water is drawn up through a different set of pipes, and much of the energy stored in the heated water is transferred to the working fluid through a heat exchanger.
The working fluid then vaporizes and passes through the turbine in order to rotate it. It then recondensed and piped back to the heat exchanger.
How Does Geothermal Energy Work?
How geothermal energy works is less complex and can be easily understood. First of all, let me explain how geothermal energy is produced. Wells of up to a mile deep or more are dug into underground reservoirs so that geothermal resources can be obtained.
These resources can be exploited from naturally occurring heat, rock, and water permeability. Also, enhanced geothermal systems, which enhance or create geothermal resources through the hydraulic stimulation process. These geothermal resources are further used to drive turbines linked to electricity generators.
The working of geothermal energy can differ depending on its end applications. I earlier mentioned the three basic uses of geothermal energy. here I will be explaining how geothermal energy is used for electric power generation.
Related: What is Tidal Energy? Its Diagram and How it Works
Advantages and Disadvantages of Geothermal Energy
Pros:
Below are the advantages of geothermal energy in its various applications.
- Environmentally friendly than conventional fuel sources such as fossil fuels.
- Geothermal energy is renewable; it can last decades.
- Geothermal energy is widely used.
- It is sustainable, stable, and a reliable source of energy.
- The energy can be used for heating and cooling in direct usage.
- No fuel is required.
- The energy generation process has been improved by new technologies, making it a rapid evolution.
- Its power output is simple to predict.
Cons:
Despite the numerous pros of geothermal energy, some limitations still occur. Below are the cons of geothermal energy in its various applications.
- Location is restricted; that is, geothermal plants must be built in places where energy is accessible.
- Environmental side effects due to the digging as some gases stored under the earth are released into the atmosphere.
- Geothermal energy can trigger earthquakes due to the alteration in the earth’s structure as a result of digging.
- High manufacturing cost of geothermal plants.
- High sustainability of geothermal energy fluid is required to be pumped back into the underground reservoirs faster.
Conclusion
Geothermal energy is renewable energy derived within the sub-surface of the earth and transported with water and/or steam to the earth’s surface. Thermal energy is the energy that determines the temperature of matter.
Thus, geothermal energy is known as thermal energy. The applications of geothermal energy can be divided into three categories: direct use, geothermal heat pumps, and electric power generation.