Renewable Energy Resources PDF

**How do humans use renewable energy resources?** By the end of this lesson, you should be able to describe how humans use energy resources and the role of renewable energy resources in society. Panels such as these can turn an unused city roof into a miniature solar energy plant. **[What are the...

**How do humans use renewable energy resources?** By the end of this lesson, you should be able to describe how humans use energy resources and the role of renewable energy resources in society. Panels such as these can turn an unused city roof into a miniature solar energy plant. **[What are the two main sources of renewable energy?]** An energy resource is a natural resource used to generate electricity and other forms of energy. Most of the energy used by humans comes from nonrenewable resources. These resources are used more quickly than they can be replaced. But renewable resources can be replaced almost as quickly as they are used. Most renewable energy resources come from the sun and some from Earth itself. **A) The Sun:** The sun\'s energy is a result of nuclear fusion. Fusion is the process by which two or more nuclei fuse together to form a larger nucleus. Fusion produces a large amount of energy, which is released into space as light and heat. Solar energy warms Earth, causing the movement of air masses. Moving air masses form winds and some ocean currents. Solar energy also fuels plant growth. Animals get energy by eating plants. Humans can harness energy from wind, moving water, plant and animal materials, and directly from the light and heat that comes from the sun. **B) Earth:** Energy from within Earth comes from two sources. One source is the decay of radioactive elements in Earth\'s mantle and crust, caused by nuclear fission. Fission is the splitting of the nuclei of radioactive atoms. The second source of energy within Earth is energy stored during Earth\'s formation. The heat produced from these sources radiates outward toward Earth\'s surface. Humans can harness this heat to use as an energy source. **Contrast Explain how energy production in the sun differs from energy production in Earth\'s interior.** Earth\'s internal energy comes from the process of nuclear fission and the events that formed Earth. **How might a renewable energy resource become nonrenewable?** All of the energy resources you will learn about in this lesson are renewable. That doesn\'t mean that they can\'t become nonrenewable resources. Trees, for example, are a renewable resource. Some people burn wood from trees to heat their homes and cook food. However, some forests are being cut down but are not being replanted in a timely manner. Others are being cut down and replaced with buildings. If this process continues, eventually these forests will no longer be considered renewable resources. **Apply Read the caption below, then describe what might happen if the community uses too much of the water in the reservoir.** A community uses this reservoir for water. The dam at the end of the reservoir uses moving water to produce electricity for the community. **Distinguish What is the difference between nonrenewable and renewable energy resources?** **How do humans use wind energy?** Wind is created by the sun\'s uneven heating of air masses in Earth\'s atmosphere. Wind energy uses the force of moving air to drive an electric generator or do other work. Wind energy is renewable because the wind will blow as long as the sun warms Earth. Wind energy is harnessed by machines called wind turbines. Electricity is generated when moving air turns turbine blades that drive an electric generator. Clusters of wind turbines, called wind farms, generate large amounts of electricity. Although wind energy is a renewable energy resource, it has several disadvantages. Wind farms can be placed only in areas that receive large amounts of wind. The equipment required to collect and convert wind energy is also expensive to produce and maintain. And the production and maintenance of this equipment produces a small amount of pollution. The turbine blades can also be hazardous to birds. Windmills such as these have been used for centuries to grind grain and pump surface water for irrigation. A wind-powered water pump can pull water from deep underground when electricity is not available. Wind farms are a form of clean energy, because they do not generate air pollution as they generate electricity. **Infer: What is the main benefit of placing these turbines in open water?** **How do humans get energy from moving water?** Like wind, moving water has kinetic energy. People have harnessed the energy of falling or flowing water to power machines since ancient times. Some grain and saw mills still use water to power their equipment. Electrical energy produced by moving water is called hydroelectric energy. Hydroelectric energy is renewable because the water cycle is driven by the sun. Water that evaporates from oceans and lakes falls on higher elevations and flows downhill in streams, rivers, and waterfalls. The energy in flowing water is converted to electrical energy when it spins turbines connected to electric generators inside the dam. Hydroelectric energy is a good source of energy only in locations where there are large, reliable amounts of flowing water. Another disadvantage of hydroelectric energy is that hydroelectric dams and their technology are expensive to build. The dams also can block the movement of fish between the sea and their spawning grounds. Special fish ladders must be built to allow fish to swim around the dam. **[How do humans use solar energy?]** Most forms of energy come from the sun---even fossil fuels begin with the sun as an energy resource. \_Solar energy\_ is the energy received by Earth from the sun in the form of radiation. Solar energy can be used to warm buildings directly. solar energy can also be converted into electricity by solar cells. **A) To Provide Energy as Heat:** We can use liquids warmed by the sun to warm water and buildings. Some liquids, such as water, have a high capacity for absorbing and holding heat. When the heat is absorbed by the liquid in a solar collector, it can be transferred to water that circulates through a building. The hot water can be used for bathing or other household uses, or to warm the building. The only pollution generated by solar heating systems comes from the manufacture and maintenance of their equipment. Solar heating systems work best in areas with large amounts of sunlight. **This calculator is powered by solar cells instead of a battery.** **B) To Produce Electricity** Solar collectors can also be used to generate electricity. First, heated fluid is used to produce steam. Then, the steam turns a turbine connected to an electric generator. Electricity can also be generated when sunlight is absorbed by a photovoltaic cell. A single photovoltaic cell produces a small amount of electricity. The electricity from joined photovoltaic cells can power anything from calculators to entire communities. Many cells must be joined together to form each solar panel, as shown in the solar power plant below. Solar power plants must be built in places with adequate space and abundant sunshine year-round. These requirements increase the costs of solar power. **Infer: Based on this image and your reading, what might be a disadvantage to using solar energy to supply electricity to a large community?** **[How do humans get energy from living things?]** Plants absorb light energy from the sun and convert it to chemical energy through photosynthesis. This energy is stored in leaves, stems, and roots. Chemical energy is also present in the dung of animals. These sources of energy make up biomass. A. **By Burning Biomass:** Biomass is organic matter from plants and from animal waste that contains chemical energy. Biomass can be burned to release energy. This energy can be used to cook food, provide warmth, or power an engine. Biomass sources include trees, crops, animal waste, and peat. Biomass is inexpensive and can usually be replaced relatively quickly, so it is considered to be a renewable resource. Some types of biomass renew more slowly than others. Peat renews so slowly in areas where it is used heavily that it is treated as a nonrenewable resource. Like fossil fuels, biomass produces pollutants when it burns. **These peat pellets will be used to generate steam in the power plant in the background. The steam will generate electricity by turning turbines.** B. **By Burning Alcohol:** Biomass material can be used to produce a liquid fuel called ethanol, which is an alcohol. The sugars or cellulose in the plants are eaten by microbes. The microbes then give off carbon dioxide and ethanol. Over 1,000 L of ethanol can be made from 1 acre of corn. The ethanol is collected and burned as a fuel. Ethanol can also be mixed with gasoline to make a fuel called gasohol. The ethanol produced from about 40% of one corn harvest in the United States would provide only 10% of the fuel used in our cars! **These wagons are loaded with sugar cane wastes from sugar production. The cellulose from these plant materials will be processed to produce ethanol.** **List What are three examples of how biomass can be used for energy?** **[How do humans use geothermal energy?]** The water in the geyser at right is heated by geothermal energy. Geothermal energy is energy produced by heat from Earth\'s interior. Geothermal energy heats rock formations deep within the ground. Groundwater absorbs this heat and forms hot springs and geysers where the water reaches Earth\'s surface. Geothermal energy is used to produce energy as heat and electricity. A. **To Provide Energy as Heat:** Geothermal energy can be used to warm and cool buildings. A closed loop system of pipes runs from underground into the heating system of a home or building. Water pumped through these pipes absorbs heat from the ground and is used to warm the building. Hot groundwater can also be pumped in and used in a similar way. In warmer months, the ground is cooler than the air, so this system can also be used for cooling. B. **To Produce Electricity:** Geothermal energy is also used to produce electricity. Wells are drilled into areas of superheated groundwater, allowing steam and hot water to escape. Geothermal power plants pump the steam or hot water from underground to spin turbines that generate electricity, as shown at right. A disadvantage of geothermal energy is pollution that occurs during production of the technology needed to capture it. The technology is also expensive to make and maintain. **Because Earth\'s core will be very hot for billions of years, geothermal energy will be available for a long time.** **List What are some advantages and disadvantages to using geothermal energy?** **Synthesize Which type of renewable energy resource would be best to use to provide electricity for your town? Explain your answer.** **Fill in the blanks with the term that best completes the following sentences.** 1 Organic matter that contains stored energy is called \_\_\_\_. 2 A resource that humans can use to produce energy is a(n) \_\_\_\_. 3 \_\_\_\_ is an energy resource harnessed from flowing water. **4 Describe Identify a major advantage and a major disadvantage of using renewable energy resources to produce electricity.** **5 Explain If renewable energy resources can be replaced, why do we need to conserve them? Use an example to support your answer.** **6 Describe What is the source of energy that powers wind and flowing water?** **True or False:** **1-Energy from the sun can be used to make electrical energy ( ).** **2-All of Earth\'s resources will last forever ( ).** **3-Food, cloth, rope, lumber, paper, and rubber come from plants ( ).** **4-Human activity can negatively affect Earth\'s resources ( ).** **5- Renewable energy resources can never run out ( ).** **6- Renewable energy resources do not cause any type of pollution ( ).** **7- Solar energy is the most widely used renewable energy resource in the United States ( ).** **8-Renewable energy resources include solar energy, wind energy, and geothermal energy ( ).** **Synthesize: You can often define an unknown word if you know the meaning of its word parts. Use the word parts and sentence below to make an educated guess about the meaning of the word geothermal:** geo- = Earth, therm- = heat Example sentence A geothermal power plant uses steam produced deep in the ground to generate electricity. geothermal: