Geothermal energy

The Earth is hot inside. This heat comes from deep down. It stays hot because of how our planet was made.

People have used this heat for a long time. They used hot springs for baths. Long ago, even the Romans used hot water for heat. Now, we use this heat to make power. This power can light up our homes. It works all the time. It does not care about the weather. It is a great way to get energy.

The Earth is very hot inside. This heat is called geothermal energy. The word comes from Greek roots. It means "hot Earth." This heat comes from two main ways. Some heat is left over from when the planet formed. Other heat comes from radioactive decay. This is a natural way that rocks stay warm.

People have used this heat for a very long time. Early people used hot springs for bathing. Long ago, the Romans used hot water for heat under floors. Today, we use this heat to make electricity. Geothermal power plants make power at a steady rate. They do not need the sun or wind to work. This makes them very reliable.

Most plants are built near the edges of tectonic plates. These are the places where the Earth's crust is thin. In 2019, there were 13,900 megawatts of this power available. That is a big amount of power for the whole world. Many countries use it to help their people.

Geothermal energy is the heat found inside the Earth. The name comes from Greek words meaning "hot Earth." This heat comes from two main sources. Some is leftover from when the planet formed. Most comes from radioactive decay in rocks. This decay keeps the Earth's interior very warm.

This energy is very reliable for humans. Unlike the sun or wind, it works at a constant rate. It does not change with the weather. There is enough of this heat to meet all our energy needs.

There are different ways to use this heat. One way is through hydrothermal systems. These systems use naturally occurring hot water or steam. In a flash plant, steam from a well powers the machinery. In a binary cycle plant, hot water heats a different liquid. This liquid turns into vapor to spin a turbine.

Some people also use enhanced geothermal systems. This involves pumping water into bedrock to create a reservoir. This helps us find heat in more places. These methods turn heat into useful power.

Humans have used geothermal heat for thousands of years. People used hot springs for bathing in the Paleolithic era. The Romans used hot springs for public baths and floor heating. In 1827, people in Italy used steam to extract boric acid. The first geothermal power generator was tested in 1904.

Prince Piero Ginori Conti tested it in Larderello, Italy. It successfully lit four light bulbs. The first commercial power plant followed in 1911. This was the only industrial producer for many years.

Today, geothermal energy is a large global industry. In 2019, there were 13,900 megawatts of geothermal power available worldwide. The United States has a large share of this capacity. In 2019, the US held 3.68 gigawatts of power.

Many countries rely on this energy for electricity. Iceland, Kenya, and the Philippines use it a lot. In 2019, the industry employed about 100,000 people. The cost to make this power has gone down over time. In 2021, a new plant in the US cost about $0.05 per kilowatt-hour.

Geothermal energy is a renewable resource. This means we use it much slower than the Earth makes it. Most plants are built near tectonic plate boundaries. These are places where the Earth's crust is thinner.

This makes it easier to reach the heat. Geothermal plants also produce very little carbon dioxide. They emit less than 5% of the gases that coal plants do. This makes it a cleaner way to power our world. It connects the deep heat of our planet to our daily lives.

Geothermal energy is thermal energy extracted from the Earth's crust. The name comes from Greek roots meaning "hot Earth." This energy is a vital resource for heating and electricity. It is considered renewable because the heat extraction rates are insignificant compared to the Earth's total heat content. Unlike solar or wind power, geothermal plants produce power at a constant rate. They do not depend on changing weather conditions. This makes geothermal energy a very reliable source of power for the planet.

The heat inside our planet comes from two main sources. About 20% of this is residual heat from planetary accretion, which is the process of the planet's formation. The remaining heat comes from the radioactive decay of naturally occurring isotopes. For example, granite with high thorium content can power the high temperature of rock through decay.

The Earth's internal thermal energy flows to the surface by conduction. This happens at a rate of 44.2 terawatts (TW). Meanwhile, radioactive decay replenishes this heat at a rate of 30 TW. These rates are more than double humanity's current total energy consumption.

There are several ways to capture this energy. Hydrothermal systems use naturally occurring reservoirs of hot water or steam. Vapor-dominated plants, like those at Larderello, use superheated steam from temperatures between 240 and 300 °C. Liquid-dominated reservoirs (LDRs) are more common near volcanoes. Flash plants are often used with these liquid sources. In a flash plant, steam is separated from liquid via cyclone separators to drive generators.

Another method is the binary cycle power station. This uses an organic fluid to capture energy from lower temperatures. In 2006, a plant in Alaska used this to produce electricity from a record low temperature of 57 °C.

When natural water is not available, engineers use enhanced geothermal systems (EGS). This process involves injecting water to hydraulically fracture bedrock. This creates an artificial hot water reservoir.

This technology allows us to access heat in a greater geographical range. Most traditional plants are built near tectonic plate boundaries. At these boundaries, the crust is thinner and the heat is closer to the surface. This makes it easier and more efficient to extract the energy.

Humans have used geothermal heat for millennia. People used hot springs for bathing during the Paleolithic era. In the first century CE, Romans used hot springs for public baths and underfloor heating. The world's oldest geothermal district heating system has operated in France since the 15th century. Industrial use began in 1827 in Larderello, Italy, to extract boric acid. In 1904, Prince Piero Ginori Conti tested the first geothermal power generator.

It successfully lit four light bulbs. The first commercial plant followed in 1911.

The geothermal industry is a significant global economic force. As of 2019, 13,900 megawatts (MW) of geothermal power was available worldwide. The industry employed about 100,000 people in 2019. The cost of generating this power has decreased significantly. During the 1980s and 1990s, costs fell by 25%. By 2021, the US Department of Energy estimated that a new plant costs about $0.05/kWh.

This makes it an increasingly competitive energy source.

Geothermal energy provides a cleaner alternative to fossil fuels. Geothermal electric stations emit an average of 45 grams of carbon dioxide per kilowatt-hour. This is less than 5% of the emissions produced by coal-fired plants. Many countries rely heavily on this resource. Iceland, El Salvador, Kenya, the Philippines, and New Zealand all use geothermal energy for a significant share of their power. As of 2024, countries like Costa Rica and El Salvador use it to provide a large percentage of their national electricity.