16.3 – Renewable Energy Sources

Objectives Analyze the need for alternative energy sources. Compare the advantages and disadvantages of various alternate energy sources Describe alternate methods for generating electricity.

Renewable resource Can be replaced almost as quickly as it is used  Example: Because only about one billionth of the Sun’s energy falls on Earth, and because the Sun is expected to continue producing energy for several billion years, solar energy cannot be used up

Solar Energy Converted into electricity by a photovoltaic cell, or solar cell A solar cell contains one layer of electron-rich semiconductor material and one layer that is electron-poor

Solar cells Energy produced by solar cells is more expensive than energy produced with fossil fuels Energy from solar cells must be stored in batteries when the sun is not shining

Hydroelectricity Produced by moving water It is about twice as efficient as fossil fuels or nuclear power

Tidal energy Uses moving water As the tide comes in, the moving water spins a turbine that generates electricity The water is then trapped behind a dam At low tide the water behind the dam flows back out to the ocean, spinning the turbines and generating electric power

Tidal energy It can only be used in places when high and low tides are different enough

Windmills Can be used to generate electricity Wind spins a propeller that is connected to an electric generator Only useful when the wind blows consistently

Geothermal energy Thermal energy contained in hot magma Limited to areas where magma is close to the surface

Alternative fuels Hydrogen gas  It produces only water vapor when it burns and creates no pollution

Alternative fuels Biomass = renewable organic matter  Such as wood, sugarcane fibers, rice hulls, and animal manure  Burned in the presence of oxygen to convert the stored chemical energy to thermal energy

In-Class Assignment/Homework Formative Assessment - “Missed Conception” – students will discuss certain misconceptions that people have about energy and explain why those misconceptions exist 16.3 WKT Objectives Analyze the need for alternative energy sources. Compare the advantages and disadvantages of various alternate energy sources Describe alternate methods for generating electricity.