P. Y aswanth K umar S anjay s ir 1

T opic NON-CONVENTIONAL SOURCE OF ENRGY 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 has a low impact on the environment; however, there are few sites where geothermal energy can be extracted economically. 2

Geothermal Energy, energy contained in intense heat that continually flows outward from deep within Earth. This heat originates primarily in the core. Some heat is generated in the crust, the planet’s outer layer, by the decay of radioactive elements that are in all rocks. The crust, which is about 5 to 75 km thick, insulates the surface from the hot interior, which at the core may reach temperatures from 4000° to 7000° C (7200° to 12,600° F). Where the heat is concentrated near the surface, it can be used as a source of energy. 3

Geysers are caused when underground chambers of water are heated to the boiling point by volcanic rock. When heat causes the water to boil, pressure forces a superheated column of steam and water to the surface. Because most geothermal reservoirs are capped by overlying rock, the heated water cannot escape, remaining underground instead. If a geothermal reservoir is sufficiently close to the surface, the heated water can be piped to the surface and used to produce energy. 4

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. 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. 5

Flash Steam Plants  Most operating geothermal power plants are flash steam plants. In a flash steam plant, hot water from wells is piped into the plant, where, released from the high pressure of its underground location, some of the hot water boils (flashes) to steam. The force of the expanding steam is used to spin a turbine generator, which produces electricity. After turning the turbine, the geothermal water, along with the condensed steam, is piped back down into the reservoir to be reheated so it can be used again. 6

Dry Steam Plant  This dry steam geothermal reservoir, which supports 20 operating power plants, produces about 1,000 megawatts of electricity, enough to supply power to nearly 2 million people.  While most geothermal reservoirs produce hot water, a small number produce mostly steam. Steam from such a reservoir is used in a dry steam plant. In such a plant, the steam is piped directly through a turbine generator. 7

Binary power plants  Binary power plants can generate electricity using geothermal reservoirs of lower temperature, increasing the number of geothermal reservoirs in the world that can potentially be used for generating electricity. Binary power plants are generally more expensive to build and operate than flashed steam plants. However, binary power plants use geothermal heat and water more efficiently and have no emissions. 8

Surface of the Sun The surface layer of the Sun is called the photosphere. Sometimes hot gas can shoot thousands of miles above the photosphere, as this picture shows. 9

Solar Energy, radiation produced by nuclear fusion reactions deep in the Sun’s core (see Nuclear Energy). The Sun provides almost all the heat and light Earth receives and therefore sustains every living being. The atmosphere and clouds absorb or scatter the other half of the incoming sunlight. The amount of light that reaches any particular point on the ground depends on the time of day, the day of the year, the amount of cloud cover, and the latitude at that point. 10

International Space Station The International Space Station gets its power from solar panels. Solar Power These solar panels convert energy from sunlight directly into electricity. Solar power is a renewable source of energy it will never run out. 11

Indirect collection solar energy  People can make indirect use of solar energy that has been naturally collected. Earth's atmosphere, oceans, and plant life, for example, collect solar energy that people later extract to power technology. Flat plate collectors are typically flat, thin boxes with a transparent cover that are mounted on rooftops facing the Sun. For applications such as air conditioning, central power generation, and many industrial heat requirements, flat plate collectors cannot provide carrier fluids at high enough temperatures to be effective. 12

Approximately 30 percent of the solar power reaching Earth is consumed by the continuous circulation of water, a system called the water cycle or hydrologic cycle. The Sun’s heat evaporates water from the oceans. The oceans also collect and store solar energy. Plants, through photosynthesis, convert solar energy to chemical energy, which fuels plant growth. People, in turn, use this stored solar energy through fuels such as wood, alcohol, and methane that are extracted from the plant life (biomass). Fossil fuels such as oil and coal are derived from geologically ancient plant life. People also eat and digest plants, or animals fed on plants, to obtain energy for their bodies. 13

Solar Home In this solar home in Corrales, New Mexico, a flat plate solar collector (lower right) provides energy to heat water pumped by the windmill. The water is stored in large drums on the side of the home. Solar Heating Flat plate collectors utilize the sun’s energy to warm a carrier fluid, which in turn provides usable heat to a household. The carrier fluid, which in this case is water, flows through copper tubing in the solar collector, and in the process absorbs some of the sun’s energy. Next, the carrier fluid moves to the heat exchange, where the carrier fluid warms water that is used by the household. Finally, a pump moves the carrier fluid back to the solar collector to repeat the cycle. 14

Wind Farm These turbines are part of a wind farm located near Lake Benton, Minnesota. This region is one of the most productive wind energy sites in the Midwestern United States. 15

Wind Energy  Wind Energy, energy contained in the force of the winds blowing across the earth’s surface. When harnessed, wind energy can be converted into mechanical energy for performing work such as pumping water, grinding grain, and milling lumber. By connecting a spinning rotor (an assembly of blades attached to a hub) to an electric generator, modern wind turbines convert wind energy, which turns the rotor, into electrical energy.  Egyptians may have been the first to capture wind energy when they sailed boats up the Nile River beginning around the 4th century BC. Wind energy has been harnessed on land since the first windmill was developed by the ancient Persians in the 7th century AD. Windmills have since been used to mill grain, pump water, saw timber, and provide other forms of mechanical energy.  In the late 20th century, windmills were developed to convert wind energy into electric power. 16

 Modern wind energy systems consist of three basic components: a tower on which the wind turbine is mounted; a rotor that is turned by the wind; and the nacelle, which houses the equipment, including the generator, that converts the mechanical energy in the spinning rotor into electricity. 17

W IND E NERGY AND THE ENVIRONMENT Although wind energy is a relatively clean means of generating electricity, there are associated impacts. One of these is the potential of an array of turbines to alter the visual quality of the landscape, especially when located in a scenic area. In addition to aesthetic concerns, noise associated with spinning wind turbine rotors has generated complaints from the public, although recent technology has done much to address this issue. 18