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Earth energy

Renewable geothermal energy

It comes from the thermal energy of the Earth. Thermal energy is the energy that determines the temperature of matter. Earth’s energy comes from the original formation of the planet and from radioactive decay of minerals. 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. The word “geothermal” comes from the Greek words “geo” – earth and “thermos” – heat. It is an inexhaustible energy source and the same way as the power from the Sun, Wind and Water it preceded life, the life that we explore in a form of fossil fuels.

History of geothermal energy

Hot springs have been used for bathing at least since paleolithic times. The oldest known spa is a stone pool on China’s Lisan mountain built in the Qin dynasty in the 3rd century BC, at the same site where the Huaqing Chi palace was later built. In the first century AD, Romans conquered Aquae Sulis, now Bath, Somerset, England, and used the hot springs there to feed public baths and underfloor heating. The admission fees for these baths probably represent the first commercial use of geothermal power. The world’s oldest geothermal district heating system in Chaudes-Aigues, France, has been operating since the 14th century. The earliest industrial exploitation began in 1827 with the use of geyser steam to extract boric acid from volcanic mud in Larderello, Italy.

In the 20th century, demand for electricity led to the consideration of geothermal power as a generating source. Prince Piero Ginori Conti tested the first geothermal power generator on 4 July 1904, at the same Larderello dry steam field where geothermal acid extraction began. It successfully lit four light bulbs. Later, in 1911, the world’s first commercial geothermal power plant was built there. It was the world’s only industrial producer of geothermal electricity until New Zealand built a plant in 1958.

Types of use

Geothermal electricity is electricity generated from geothermal energy. Technologies in use include dry steam power plants, flash steam power plants and binary cycle power plants. Geothermal electricity generation is currently used in 24 countries, while geothermal heating is in use in more than 70 countries.

Geothermal power is  immune to wind fluctuations or sun radiation. However, capital costs tend to be high. Drilling accounts for over half the costs, and exploration of deep resources entails significant risks.

Geothermal power is highly scalable: a small power plant can supply a rural village, though capital can be high.