Alternative Energy
Earth and Space
Earth’s Energy Resources: Geothermal
Geothermal energy comes from heat deep under the ground. This energy is
produced in the core of Earth.
Geothermal energy can be captured as steam or hot water. It can be found at hot
springs, geysers, and volcanoes. Most geothermal sites are found near hot spots.
These are places where magma from deep within Earth comes closer to the surface.
In the United States, Hawaii and states in the west have the most geothermal sites.
Geothermal energy can also be used to make electricity. The steam turns the
turbines on giant generators. The generators produce electricity.
California has the most power plants that use geothermal energy. “The Geysers” in
Northern California has been producing electricity this way since 1960.
Hot water from the ground can be sent through pipes throughout a building to
provide heat for the building. This is done in Iceland.
Using geothermal energy to produce electricity is a very clean process. No fuels are
burned, so these power plants give off very little harmful material.
Geothermal power plants release less than 1% of the carbon dioxide given off by
power plants that burn fossil fuels. However, geothermal energy is typically available
only at its source and cannot be easily stored and transported for use in another
place. Also, geothermal plants cost a lot of money to build.
After use, the water is injected back into the earth.
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Alternative Energy
Earth and Space
Earth’s Energy Resources: Hydroelectricity
Hydroelectric energy comes from moving water. Swiftly flowing rivers or falling water
can carry large amounts of energy. This energy can be used by machines or for
generating electricity. Many hydropower sources in the U.S. can be found in the
mountain states in the west and near the Great Lakes.
Water pushes against the blades of a turbine to spin a generator that makes
electricity.
Dams can be built to capture the energy from a river. They can stop the flow of the
river and create reservoirs to store the water. The water is released when it is
needed.
Hydropower facilities can change the water temperature and river’s flow. This can
harm aquatic wildlife. Also, the dams can change where the river flows, and the
reservoirs can flood the surrounding land.
However, making electricity this way does not release pollution into the air or
produce chemical runoff or toxic waste.
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Alternative Energy
Earth and Space
Earth’s Energy Resources: Biofuels
Biofuels come from living materials. Plants capture energy from the Sun. This energy
is transferred to animals when they eat plants. The most common sources of biofuels
are trees, crops, manure, and garbage.
One way to release the energy captured in biomass is by burning.
All sorts of waste materials can be burned to create steam and electricity. In wasteto-energy plants, these materials are burned just like coal to make steam. The steam
turns the turbines that produce electricity. However, these power plants cost more
than conventional ones that burn fossil fuels.
The energy trapped in garbage can be converted in other ways, too. When dead
plants and animals decay, they produce methane. This is a colorless, odorless gas.
Wells drilled into some landfills tap into the methane-produced electricity.
Biomass materials can also be changed into transportation fuels. Biodiesel can be
made from vegetable oils and animal fats. Texas has more biodiesel capacity than
any other state in the nation!*
Burning biomass can pollute the air, but not as much as fossil fuels do. On the other
hand, it reduces the amount of garbage stored in landfills.
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Alternative Energy
Earth and Space
Earth’s Energy Resources: Wind
Wind energy comes from moving air. It is created when the Sun heats Earth.
The windiest places are the tops of hills, open plains or shorelines, and gaps
between mountains. In southern California, wind blows more in the summer due to
the extreme heating of the desert during the day. At night, cooler air from the Pacific
Ocean rushes in. However, in Montana, the wind blows more in the winter.
Texas has the largest wind market in the nation, responsible for 7.8% of electricity
generated in 2010.*
Modern wind machines can be as tall as a 20-story building. Each blade can span
200 feet across. At wind farms, dozens of windmills cover a large area. The world’s
largest wind farm is in Texas and has 421 wind machines!
Wind machines can only run when the wind blows about 14 mph or more. At most
wind farms, the wind is only right for producing electricity about two-thirds of the
time.
Windmills are a clean energy source.
No fuels are burned, so no pollution is created.
Wind energy is a renewable resource.
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Alternative Energy
Earth and Space
Earth’s Energy Resources: Solar
Solar energy comes from the Sun.
Life on Earth depends on the Sun’s energy.
We can use the Sun’s energy to warm spaces or heat water.
Solar energy can also be used to produce electricity. At solar thermal power plants,
curved mirrors reflect sunlight onto a pipe that contains a special liquid. When the
liquid is heated, it is used to produce steam for generators that make electricity. The
largest solar power plants in the world are located in California’s Mojave Desert.
Texas is also a leader in the amount of electricity it can produce from solar energy.
West Texas alone has 75% more exposure to direct sunlight than east Texas,
making it a good place for projects supporting energy production from sunlight.*
Another way to produce electricity from sunlight is through photovoltaic cells.
The energy can be used directly or stored in batteries.
Solar energy is clean since no fuels are burned. The amount of solar energy
available depends on the time of day, season, weather conditions, and our location
on Earth, and there’s no sunlight available at night!
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