5.3 Renewable Energy Resources
Lesson Objectives
- Describe different renewable resources, and understand why they are renewable.
- Understand that the sun is the source of most of Earth’s energy.
- Describehowenergyiscarriedfromoneplacetoanotherasheatandbymovingobjects.
- Understand how conduction, convection, and radiation transfer energy as heat when
renewable energy sources are used. - Understand that some renewable energy sources cost less than others and some cause
less pollution than others. - Explain how renewable energy resources are turned into useful forms of energy.
- Describe how the use of different renewable energy resources affects the environment.
Introduction
What if we could have all of the energy we needed and never run out of it? What if we
could use this energy without polluting the air and water? In the future, renewable sources
of energy may be able to provide all of the energy we need. Some of these resources can give
us “clean” energy that causes little or no pollution.
Plenty of clean energy is available for us to use. The largest amount of energy to reach
Earth’s surface is from solar radiation. Each year is 174 petawatts (1.74 x 1017 W) of
energy from the sun enter the Earth’s atmosphere. Because the planet’s interior is hot, heat
flows outward from the interior, providing about 23 terawatts (2.3 x 1013 W) of energy per
year. By contrast, the total world power consumption is around 16 terawatts (1.6 x 1013W)
per year. So solar or geothermal energy alone could provide all of the energy needed for
people if it could be harnessed.
Solar Energy
When you think of the sun, you probably think of two things—light and heat. The sun is
Earth’s main source of energy, and light and heat are two different kinds of energy that the
sun makes. The sun makes this energy when one element, called hydrogen, changes into
another element, called helium. Changing hydrogen into helium releases huge amounts of
energy. The energy travels to the Earth mostly as visible light. The light carries the energy
through the empty space between the sun and the Earth in a process calledradiation. We
can use this light from the sun as an energy resource called solar energy (Figure5.6).
Solarenergy is a resource that has been used on a small scale for hundredsof years. Its use on
a larger scale is just starting to ramp up and people increase production of renewable energy
sources. One focus of solar power development in the United States is the desert southwest.