Chapter 5: Energy Resources Section 2, Renewable Sources of Energy

What are we learning today? 1. What forms of energy does the sun provide? 2. What are some renewable sources of energy? Key Terms: Solar energy Hydroelectric power Biomass fuel Gasohol Geothermal energy

Renewable Sources of Energy I. Harnessing the Sun’s Energy- A. Solar energy- energy from the sun The sun constantly gives off energy in the forms of light and heat. 1. does not cause pollution 2. will not run out for billions of years 3. produces enough energy for 40 years in one day 4. Collection methods of solar power have been created

B. Solar Power Plants 1. rows of mirrors focus the sun’s rays to heat a tank of water. Water boils = steam = generates electricity C. Solar Cells 1. solar energy directly converted to electricity 2. has a negative and positive terminal

3. power calculators, lights and other small devices D. Passive Solar Heating 1. converts sunlight into thermal energy 2. occurs in a parked car on a sunny day Ex: -solar energy passes through windows and heats the seats and other car parts - inside temp of car increases as heat is transferred to the air

E. Active Solar Heating (pg. 167, Figure 7) 1. captures sun’s energy and uses pumps and fans to distribute the heat. a. 1 st light hits the solar cells = converted to thermal energy b. Water in pipes absorbs the thermal energy c. Heated water flows to a storage tank d. Pumps and fans distribute heat throughout the building

II. Hydroelectric Power Other renewable sources of energy include water, the wind, biomass fuels, geothermal energy, and hydrogen A. Hydroelectric power- is electricity produced by flowing water. 1. water turn turbines as it flows through tunnels at the bottom of a dam 2. most widely used source of renewable energy 3. provides a steady source of energy 4. does not create air pollution and is fairly inexpensive (once dam is built) 5. negative = most rivers have already been dammed. 6. damming a river can cause harm to an env’t

III. Capturing the Wind A. Wind energy = and indirect form of solar energy 1. different areas have different pressures due to uneven heating of the Earth’s surface 2. winds are created from differences in pressure 3. wind turns a turbine to generate electricity 4. does not cause pollution 5. drawbacks = few locations with winds that blow steady - wind generators are noisy -wind generators can be destroyed by too strong of winds

IV. Biomass Fuels- are made from living things Ex: wood, leaves, food wastes, manure A. Can be converted into other fuels 1. corn, sugar cane can be used to make alcohol Ex: gasohol-adding alcohol to gasoline - gasohol used as fuels for cars Ex: bacteria produces methane gas as it decomposes biomass materials= gas is then used to heat buildings Ex: Soybeans produce oil that is used as a fuel = biodiesel fuel

2. are renewable resources, but producing methan gas and alcohol is expensive 3. Not as widely used

V. Tapping Earth’s Energy- A. Geothermal energy- the intense heat from Earth’s interior that warms the magma 1. used to generate electricity 2. can capture the energy from the hot water and steam to heat homes 3. unlimited supply of cheap energy 4. Disadvantage = only few places where magma comes close to earth’s surface -drilling deep wells is expensive

The Promise of Hydrogen Power- A. Most all Hydrogen is combined with Oxygen in the form of water, so… B. Pure hydrogen is obtained by passing an electric current through water - takes more energy to produce than it provides to burn C. Hydroelectric and solar power plants can use the extra or unused energy to produce hydrogen D. Cars are now being developed to run on hydrogen fuel cells. - emissions would be water