Matter & Energy


Matter is composed of atoms or groups of atoms called molecules. The arrangement of particles in a material depends on the physical state of the substance. In a solid, particles form a compact structure that resists flow. Particles in a liquid have more energy than those in a solid. They can flow past one another, but they remain close. Particles in a gas have the most energy. They move rapidly and are separated from one another by relatively large distances.

Geothermal Power Plants

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Geothermal Energy Plant
Geothermal energy plants generate electricity and heat by harnessing the heat energy contained within the earth. The earth transfers its energy to deep-lying circulating water, which the plants access with wells and pumps. Geothermal energy is attractive because it creates almost no environmental pollution. However, the number of sites where geothermal energy can be economically extracted is limited.

Geothermal reservoirs within about 5 km (about 3 mi) of Earth’s surface can be reached by drilling a well. The hot water or steam from wells can be used to turn turbine generators to produce electricity. A power plant that uses this natural source of hot water or steam is called a geothermal power plant.

At the beginning of the 21st century, there were some 380 geothermal power plants in 22 countries around the world with a combined installed capacity of about 8,000 megawatts. Geothermal energy provided 1.6 percent of the world’s total electricity, serving the electricity needs of about 60 million people, mostly in developing countries. About 2.5 percent of the electricity produced in the United States came from geothermal power plants. The electricity produced from geothermal power in the United States represented about 37 percent of the world’s output of electricity from geothermal power. The United States, the Philippines, Italy, Mexico, Indonesia, Japan, New Zealand, and Iceland are the largest producers of geothermal energy.

There are three types of geothermal power plants: flash steam plants, dry steam plants, and binary plants.