Does Geothermal Energy Come From Tectonic Plates?

Table of Contents

What is Geothermal Energy?

Geothermal energy is heat derived from the natural heat of the earth’s interior. It is a renewable energy source that utilizes the heat generated in the earth’s core and stored in rocks and fluids within the earth’s crust (https://www.energy.gov/eere/geothermal/geothermal-basics). The word “geothermal” comes from the Greek words geo (earth) and therme (heat).

Geothermal energy consists of thermal energy generated and stored in the Earth. The geothermal energy of the Earth’s crust originates from the original formation of the planet, from radioactive decay of minerals, and from solar energy absorbed at the surface. The geothermal gradient, which is the difference in temperature between the core of the planet and its surface, drives a continuous conduction of thermal energy in the form of heat from the core to the surface (https://www.twi-global.com/technical-knowledge/faqs/geothermal-energy).

Geothermal energy is considered a renewable energy source because the heat emanating from the interior of the Earth is continuously replenished.

How Geothermal Energy Works

Geothermal energy is thermal energy generated and stored in the Earth (
https://www.ucsusa.org/resources/how-geothermal-energy-works). It originates from the heat within the Earth’s core produced by the slow decay of radioactive particles, as well as heat from the Earth’s mantle and crust. The high temperatures in the Earth’s interior provide a nearly limitless supply of heat. This heat constantly flows outward towards the surface.

The Earth has a geothermal gradient, which means that the temperature increases with increasing depth from the Earth’s surface (
https://www.energy.gov/eere/geothermal/electricity-generation). Areas with high geothermal gradients can reach temperatures of over 200°C just a few kilometers deep. In some places, magma comes close enough to the surface to heat underground water into superheated steam.

This naturally occurring steam can be tapped at the surface and used to drive turbines and generate electricity. Hot water near the Earth’s surface can also be pumped up and run through a heat exchanger to provide hot water and heat for various applications.

Types of Geothermal Energy Systems

There are three main types of geothermal energy systems:

Hydrothermal Systems

Hydrothermal systems utilize naturally occurring pockets of steam or hot water located underground to generate geothermal energy. Wells are drilled into geothermal reservoirs to pump the steam or hot water to the surface. The steam can then be used to drive turbines and generate electricity. According to the Department of Energy, hydrothermal systems are currently the most common form of geothermal power generation.

Enhanced Geothermal Systems (EGS)

EGS, also known as engineered geothermal systems, work by pumping water into hot dry rocks deep underground at high pressures. This creates new cracks and fissures in the rocks, allowing water to circulate through and become heated. The now superheated water is pumped back to the surface to generate electricity. EGS systems are not yet widely used but have great potential, especially in areas without natural hydrothermal reservoirs.

Direct Use

Direct use geothermal systems utilize reservoirs of hot water near the Earth’s surface for applications like heating buildings, greenhouses, fish farms, and bathing. According to Executive Cooling, hot water is accessed via wells or hot springs and can be used directly or in heat pumps to provide heating and hot water. Direct use systems are simple and efficient for localized heating applications.

Uses of Geothermal Energy

Geothermal energy has a wide variety of uses, with the top three being electricity generation, heating, and agricultural applications.

One of the main uses of geothermal energy is to generate electricity. Geothermal power plants use steam from reservoirs of hot water found deep underground to spin turbine generators and produce electricity. According to the U.S. Department of Energy, geothermal power plants produced about 17 billion kilowatt-hours of electricity in 2021, which was enough to power around 1.5 million average U.S. households.

Geothermal energy is also commonly used for heating purposes, often through geothermal heat pumps. These systems take advantage of the constant temperatures underground to control temperatures above ground. They can be used to heat individual homes, buildings, districts, or even entire cities. Iceland notably uses geothermal energy to heat around 90% of its buildings.

In agriculture, geothermal energy can be used to heat greenhouses and dry crops. The heat can enable plants to grow year-round in colder climates and helps foods like vegetables, fruits, and grains dry faster after harvesting. Geothermal heat has also been used to pasteurize milk at dairy facilities.

Other applications include aquaculture, industrial processes, bathing, and recreational purposes like hot springs and spas. Overall, geothermal energy provides reliable and sustainable heating and power across many aspects of daily life.

Geothermal Energy and Tectonic Plates

Geothermal energy is often found along tectonic plate boundaries where there is volcanic activity. The movement of tectonic plates causes magma deep within the Earth to rise closer to the surface, which heats up rocks and water in the crust. This allows higher temperature geothermal resources to form.

For example, Iceland is located on the Mid-Atlantic Ridge, which is the tectonic plate boundary between the North American Plate and the Eurasian Plate. This divergence of plates causes magma upwelling from the mantle, creating many hot spots and volcanoes across Iceland. This makes Iceland an ideal location for geothermal energy, providing over 25% of the country’s electricity needs [1].

Another example is along the Pacific “Ring of Fire”, where the Pacific Plate meets and collides with surrounding plates. This convergent plate boundary has high earthquake and volcanic activity, creating geothermal resources across countries like the United States, New Zealand, and Indonesia. Around the rim of the Pacific Ocean, geothermal energy provides over 6.5 gigawatts of power [2].

In summary, the earth’s tectonic plate movements often indicate where substantial geothermal resources can be found. The geologic activity from plate boundaries results in ideal conditions for geothermal energy generation.

Advantages of Geothermal Energy

Geothermal energy offers several key advantages that make it an attractive renewable energy source. Some of the main benefits of geothermal energy include:

Renewable – Geothermal energy is considered renewable because the heat from the Earth’s core is constantly being replenished (1). The geothermal energy available in reservoirs can be sustained indefinitely if the reservoirs are managed properly.
Sustainable – Geothermal power plants produce electricity 24/7 and do not rely on variable sources like wind or sunlight. The consistent energy production makes geothermal a reliable and sustainable energy source (2).
Reduces emissions – Geothermal energy produces minimal emissions because it does not require the burning of fossil fuels. The emissions from geothermal power plants are typically at least 90% lower per kWh than conventional fossil fuel plants (1).

Overall, geothermal stands out as a clean, renewable alternative to fossil fuels. The ability to harness geothermal energy in a sustainable way with low emissions makes it an attractive option to reduce dependence on coal, oil, and natural gas.

Disadvantages of Geothermal Energy

While geothermal energy has many benefits, it also comes with some drawbacks. One of the main disadvantages of geothermal energy is the high upfront costs required for installation. Drilling geothermal wells can be an expensive process, with costs often ranging from $300,000 to $1 million per well, according to this source. The actual geothermal power plant also requires significant capital to construct.

Another disadvantage is that geothermal energy is restricted to specific geographical locations. Geothermal power plants need to be built in areas with optimal underground temperatures and geologic features, usually found along tectonic plate boundaries and seismically active zones. This limits where geothermal plants can be built, as noted in this overview.

There are also some emissions associated with geothermal energy. While geothermal plants emit far fewer greenhouse gases than fossil fuel plants, geothermal reservoirs can release small amounts of chemicals, gases, and heavy metals that must be managed and controlled, as explained in this article. Proper reservoir development and plant operation helps minimize any potential emissions.

Future of Geothermal Energy

Geothermal energy has significant potential for growth in the coming decades with the development of enhanced geothermal systems (EGS). EGS allows for the production of geothermal energy from areas that lack natural hydrothermal resources by creating artificial reservoirs in hot dry rock through hydraulic fracturing. According to research from the MIT Energy Initiative, EGS could provide 100 gigawatts of electricity in the United States by 2050, meeting around 10% of the nation’s energy needs¹. Globally, the International Energy Agency projects installed geothermal capacity could grow from 14 gigawatts today to almost 60 gigawatts by 2050 under their Sustainable Development Scenario². Realizing this potential will require advances in areas like subsurface imaging and modeling, drilling technologies, and reservoir stimulation techniques.

With increased investment and research, geothermal energy using EGS has the capability to provide consistent, baseload renewable power across large swaths of the world. Hybrid geothermal systems combining geothermal, solar, and storage technologies also show promise as a way to provide clean firm power³. While growth may start slow, geothermal’s advantages as a renewable source of electricity, heating, and cooling ensure it will play an expanding role in the global energy transition.

Major Geothermal Countries

Some of the leading countries using geothermal energy include:

United States – The U.S. generates the most geothermal power in the world, with over 3,700 MW of installed capacity. Major geothermal fields are located in California, Nevada, Utah, Hawaii, Idaho and Oregon.
Philippines – The Philippines ranks second globally in geothermal power generation with almost 2,000 MW of installed capacity. The country sources over 20% of its electricity from geothermal.

Indonesia – Indonesia has over 2,400 MW of installed geothermal capacity, making it third in the world. The country has 40 active geothermal fields spread across different islands.
Mexico – Mexico has just under 1,000 MW of installed geothermal capacity and is rapidly expanding development. Major geothermal plants are located at the Cerro Prieto field.

These countries heavily utilize their substantial geothermal resources, accounting for a significant portion of renewable energy generation. Continued expansion of geothermal power will help them meet rising electricity demands in a sustainable manner.

Conclusion

In summary, geothermal energy comes from harnessing the natural heat within the earth. This heat comes from natural radioactive decay in the earth’s core, residual heat from planetary accretion and core formation, and frictional heating caused by denser core material sinking downward. While tectonic plate movement releases some of this heat, geothermal energy does not directly come from tectonic plates.

Rather, geothermal energy utilizes the constant temperature gradients that exist in the earth’s crust, independent of tectonic activity. Areas with current or geologically recent volcanism and tectonic movement often have higher temperature gradients that make geothermal energy extraction more viable. However, geothermal resources can be found across all types of geologic settings if drilling deep enough.

In conclusion, while geothermal energy relies on the earth’s internal heat, which is partially dissipated by tectonic processes, the energy itself does not directly originate from plate tectonics. Geothermal energy harnesses the planet’s vast natural thermal resources, providing a sustainable and renewable source of power.