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 usedExample: 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 waterIt is about twice as efficient as fossil fuels

or nuclear power

Tidal energy

Uses moving waterAs the tide comes in, the moving water

spins a turbine that generates electricityThe water is then trapped behind a damAt 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 generatorOnly useful when the wind blows

consistently

Geothermal energy

Thermal energy contained in hot magmaLimited to areas where magma is close to

the surface

Alternative fuels

Hydrogen gasIt produces only water vapor when it burns and

creates no pollution

Alternative fuels

Biomass = renewable organic matterSuch 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

Missed Conception” – students will discuss certain misconceptions that people have about energy and explain why those misconceptions exist

16.3 WKT Directed Reading WKTs