Science ~ chapter 12 energy and material resources

Science ~ chapter 12energy and material resources Miss Nelson

Section 1 Renewable Sources of Energy

Anticipatory set What other sources can you name besides coal, oil, and natural gas?

standards S 6.6.a- Students know the utility of energy sources is determined by factors that are involved in converting these sources to useful forms and the consequences of the conversion process S 6.6.b- Students know the different natural energy and material resources, including air, soil, rocks, minerals, petroleum, fresh water, wildlife, and forests; and know how to classify them as renewable or nonrenewable

The big idea What forms of energy does the sun provide? What are some renewable sources of energy?

Key terms • Solar energy – energy from the sun • Hydroelectric power – electricity produced using the energy of flowing water • Biomass fuel – fuel made from living things

Key terms • Gasohol – a mixture of gasoline and alcohol • Geothermal energy – heat from Earth’s interior • Tide – the regular rise and fall of Earth’s waters along its shores

Renewable sources of energy Read Renewable Sources of Energy on page 485 of your textbook.

Harnessing the sun’s energy The sun constantly gives off energy in the forms of light and heat

Harnessing the sun’s energy • Solar energy is the source (either directly or indirectly) of most other renewable energy resources • Solar energy does not cause pollution, and will not run out for billions of years • Disadvantages • It is only available when the sun is shining • Sunlight is very spread out – to obtain a large amount of power, it is necessary to collect solar energy from a large area

Solar power plants • One way to capture the sun’s energy involves using giant mirrors • In a solar power plant, rows of mirrors use the sun’s rays to heat a tank of water • The water boils, creating steam, which can be used to generate electricity

Solar cells • Solar energy can be converted directly into electricity in a solar cell • Has a negative and positive terminal (like a battery) • When light hits the cell, and electric current is produced • Solar cells power some calculators, lights, and other small devices

Passive solar heating • Can be used to heat buildings • Converts sunlight into thermal energy • Distributed with pumps or fans • Just like a car heating up on a hot day

Active solar heating • Captures the sun’s energy and then uses pumps and fans to distribute the heat • Light strikes the dark metal surface of a solar collector • Converted to thermal energy • Water is pumped through pipes in the solar collector to absorb the thermal energy • The heated water flows to a storage tank and fans distribute the heat throughout the building

Harnessing the sun’s energy Read Harnessing the Sun’s Energy on page 486 of your textbook

Hydroelectric power Other renewable sources of energy include: • Water • Win • Biomass fuels • Geothermal energy • The tides

Hydroelectric power • Solar energy is the indirect source of water power (heat from the sun drives the water cycle) • Hydroelectric power is electricity produced by flowing water • A dam across a river controls the flow, which turns turbines creating power • Hydroelectric power is the most widely used source of renewable energy

Hydroelectric power Read Hydroelectric Power on page 488 of your textbook

Wind power • Is also an indirect form of solar energy • The sun heats the Earth’s surface unevenly. As a result, different areas of the atmosphere have different temperatures and air pressures, which causes wind as air moves from one area to another • Wind can be used to turn a turbine and generate electricity

Wind power • The fastest growing energy resource • Drawbacks: • Many areas do not have sufficiently strong winds to support wind farms • Wind farms require a lot of land • Wind often blows strongest in scenic areas, where people object to seeing wind turbines

Wind power Read Wind Power on pages 488-489 of your textbook

Biomass fuels • Wood was probably the first fuel ever used for heat and light • Wood belongs to a group of fuels called biomass fuels • Are made from material that was once part of a living thing • Other biomass fuels include leaves, food wastes, and manure • Biomass fuels can also be converted into other fuels • Some crops can be used to make alcohol; adding this to gasoline forms gasohol, and can be used in fuel for cars • Methane gas can be used to heat buildings

Biomass fuels • Are renewable resources • …but it takes time for new trees to replace those that have been cut down • Are not widely used in the United States

Biomass fuels Read Biomass Fuels on page 489 of your textbook

Tapping earth’s energy • Below Earth’s surface are pockets of very hot liquid rock called magma • In some places it is very close to the surface • The intense heat from Earth’s interior that warms the magma is called geothermal energy • In certain places (Iceland and New Zealand) magma heats underground water to a boiling point • Hot water and steam can be valuable sources of energy

Tapping earth’s energy • Geothermal energy is an unlimited source of cheap energy • Disadvantages: • Only a few places where magma comes close to Earth’s surface • Other places, very deep wells would be needed to tap this energy

Tapping earth’s energy Read Tapping Earth’s Energy on page 490 of your textbook

Tidal energy • The tides are the regular rise and fall of Earth’s waters along its shores • Caused by the gravitational pull of the moon and sun • Tidal power plants have been built to take advantage of this regular motion • Although it is a clean, renewable source of energy, it has several limitations • There are only a few places in the world where the tides are high and low enough to build plants • A dam across a bay would block boats and fish from passing through

Tidal energy Read Tidal Energy on page 491 of your textbook

Check for understanding What two forms of energy does the sun supply? What are two reasons that solar energy has not replaced energy from fossil fuels?

Check for understanding What two forms of energy does the sun supply? The two forms of energy the sun produces are heat and light energy. What are two reasons that solar energy has not replaced energy from fossil fuels? Tworeasons that solar energy has not replaced energy from fossil fuels are that solar energy is only available when the sun is shining, and that it must be collected from a very large area.

Guided practice List five renewable energy sources other than solar energy. Which of these forms are actually indirect forms of solar energy? Explain.

Guided practice List five renewable energy sources other than solar energy. Fiver non-solar renewable energy sources are wind, water, biomass, geothermal, and tidal energy. Which of these forms are actually indirect forms of solar energy? Explain. Wind and water energy are actually indirect forms of solar energy because water power depends on the water cycle, which is driven by the sun, and wind energy depends on uneven heating of the Earth by the sun.

Independent practice Complete Energy 12-2 Independent Practice

Science ~ chapter 12 energy and material resources