Wind Energy

1. Wind Energy • Wind energy is a form of indirect solar energy • The atmosphere is warmed by the radiant energy of the sun. • Wind is caused by the uneven warming of the atmosphere, the varying topography of the earth, and the rotation of the earth. • The flow of the wind is modified by the earth’s terrain, obstacles (such as trees and buildings), bodies of water, etc. • A wind turbine converts the kinetic energy in wind into electricity. • The kinetic energy of the wind rotates the blades of a wind turbine. • The blades rotate a shaft and convert the kinetic energy of wind into mechanical energy. • The shaft of the turbine is connected to a generator, which converts the mechanical energy to electrical energy. Source: Wind Energy Program, U.S. Department of Energy (http://www.eren.doe.gov/wind/)

2. Hydropower • Hydropower is a form of indirect solar energy • Water constantly moves through a global hydrological cycle driven by the sun. • Water evaporates from the surfaces of lakes and oceans and rises into the atmosphere. • The moist warm air rises, cools, and condenses to forms clouds. • Water is transported through the atmosphere in clouds and as water vapor. • Water precipitates to the surface of the earth in the form of rain, snow, sleet, or freezing rain. • Water flows into lakes, rivers and streams and is carried back to the oceans. • Hydropower plants convert the kinetic energy of falling water into electricity. • A dam is built to control the flow of water, increase the elevation, and form a reservoir to harness the potential energy of elevated water. • As water is released, gravity causes water to flow through the penstock. • The moving water turns a turbine at the base of the dam, converting the kinetic energy of water into mechanical energy. • The shaft of the turbine is connected to a generator, which converts the mechanical energy to electrical energy. Source: Hydropower Program, U.S. Department of Energy (http://hydropower.inel.gov/more.htm)

3. Source: USGS (http://wwwga.usgs.gov/edu/hyhowworks.html)

4. Fossil Fuels • Fossil Fuels are the remnants of organisms that lived 300 million years ago. • The sun provides energy which plants use to produce energy through photosynthesis. • Plants accumulate energy throughout life and eventually die. • Plant life decays and is buried under water and rock at very high pressures. • These ancient seas recede, exposing fossil fuels such as coal and petroleum buried in the rock. • For every ten feet of plant matter, there is roughly one foot of coal. • Fossil Fuel burning plants convert chemical energy into thermal energy, thermal energy into mechanical energy, and mechanical energy into electrical energy. • A boiler combusts fuel, and uses the resulting heat to boil water. • This high pressure steam processes through the plant, powering a turbine. • The shaft of the turbine is connected to a generator, which converts the mechanical energy to electrical energy. Source: Fossil Fuel Program, U.S. Department of Energy (http://fossil.energy.gov)

5. Solar Power • On the sun, fusion reactions continually occur, releasing energy – solar radiation. • Two pairs of protons fuse, and the two products of these reactions fuse with an additional proton. • The three proton nuclei then fuse together to form beryllium-6, which is highly unstable. • The beryllium-6 decays into a helium nucleus (alpha particle) and two protons. • Along the way, gamma rays, or solar radiation (γ), is released. • Some of this solar radiation reaches the earth and strikes a photovoltaic cell. • Light that is not reflected and has a specific amount of energy is absorbed by the cell. • The energy absorbed from the light frees electrons from the semiconducting layers, generating an electric current. • This power can then be used at the source, or stored until a later time when it is needed. Source: Fusion Energy Sciences Program and Photovoltaics Program, U.S. Department of Energy (http://wwwofe.er.doe.gov, http://www.eren.doe.gov/)

6. Nuclear Power • Nuclear fission occurs inside what is known as a reactor. • A neutron collides with a uranium nucleus and is absorbed • The nucleus is induced to split into two smaller nuclei (fission products) and other neutrons. • The mass that is lost in the process is released in the form of thermal energy. • The other neutrons cause further fission reactions. • The energy released from fission is used to generate electrical energy. • Water surrounding the reactor is boiled by the thermal energy released in fission. • The thermal energy of the newly produced steam powers a turbine. • The mechanical energy of the turbine generates electrical energy in the same way as a wind turbine, or the turbine in a fossil fuel plant. Source: Nuclear Energy Program, U.S. Department of Energy (http://www.eia.doe.gov)

7. Geothermal Power • Thermal energy from molten rock heats water below the surface of the earth. • Underground water, stored under high pressure, is heated by molten rock. • A heat pump takes this warm water, which either boils under the lower pressure, is already steam, or is used to boil a second liquid with a lower boiling point than water. • The resulting steam then powers a turbine, and electrical energy is generated. • Water is pumped back into the ground, where it is again heated and placed under high pressure. Source: Geothermal Energy Program, U.S. Department of Energy (http://www.eren.doe.gov/RE/geothermal.html)

8. Biomass Power • Energy from the sun is absorbed by trees and other organic life forms. • Solar radiation, the product of fusion, is absorbed by plants and converted to energy by a process known as photosynthesis. • Plants grow, and are eventually used for industrial or agricultural purposes. • Organic material left over from these primary uses are collected by combustion plants. • Biomass fuel is used in the same way as fossil fuel, to convert chemical energy into thermal energy, thermal energy into mechanical energy, and finally mechanical energy into electrical energy. Source: Biomass Fuels Program, ONRL (http://www.ornl.gov)

9. 2. Transmission Substation 3. High Voltage Transmission Lines 1. Power Plant steps the voltage up to 69,000 - 765,000 V moves power over long distances on the transmission grid generates 3-phase AC power 6. Distribution Power Lines 5. Distribution Substation 4. Subtransmission Steps the voltage down to 22,000 – 69,000 V steps the voltage down to 4160 -36,000V Moves power over distribution grid to points-of-use Generation, Transmission, & Distribution

10. Small Substation Distribution Power Lines 2400 – 15,000 Volts 480Y/277 Volts 1200 A Residential Uses 120/240 Volts Distribution Industrial Uses 6. Distribution Power Lines Commercial Uses