-L’énergie de la terre

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geothermie une energie pour demain?

You don’t have to live in Iceland to enjoy the benefits of thermal hotsprings, or to produce electricity or heat greenhouses with geothermal energy. Even in central Paris, where there isn’t a volcano in sight, some buildings (such as the Maison de la Radio) are heated in this way. Other countries, from the United States to New Zealand and the Philippines, also use geothermal energy.

The Earth beneath our feet is hot rising in temperature by 5.4°F (3°C) every 320 feet (100 meters) and reaching 7,000?F (4,000°C) at its core. Water circulates within the Earth’s crust at different depths, and is heated by the surrounding rock. Some of this hot water breaks through to the surface in the form of hot springs or geysers.

This source of heat can be exploited in various ways. High-temperature underground water sources are used by geothermal power plants to produce electricity. At a depth of 1,650 feet (500 meters) beneath the Earth’s surface, super-heated water between 300°F and 650°F (150°C and 350°C) turns into steam, creating a pressure-cooker effect. The steam is accessed and used to drive a turbine which generates electricity. Geothermal resources suitable for electricity production are common around the Pacific (accounting for 28% of the electricity produced in the Philippines), in Russia and Central and Eastern Europe. But on a global scale, geothermal power meets less than 1% of electricity demand.

Low-temperature geothermal sources are used for heating buildings. Hot water between 70°F and 300°F (20°C and 150°C) circulating around porous rocks in the ground is piped into buildings, greenhouses, and fish farms. Finally, very low-temperature geothermal waters from closest to the Earth’s surface are used to power air conditioning units and heating systems of individual houses.

Today, technologies such as heat pumps and geothermal power plants are sophisticated and competitive enough to permit the development of this under-valued form of energy. With geothermal power, the Earth itself can provide us with a clean, renewable energy that is available night and day, and is completely safe for the environment.

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