environmental science chapter 18 section 1. energy from sources that are constantly being formed. ...
TRANSCRIPT
Renewable Energy Today
Environmental ScienceChapter 18 Section 1
Energy from sources that are constantly being formed.
Examples:◦ Solar◦ Wind◦ Water◦ Earth’s heat
Renewable Energy
Only a small fraction of the sun’s energy reaches the Earth.
The energy is enough to power the wind, plant growth, and the water cycle.
All forms of energy come either directly or indirectly from the sun.
Solar Energy – Power from the Sun
Passive Solar Heating◦ Uses the sun’s energy to heat something directly.◦ May use windows facing the direction where the
sun strikes most directly in order to heat a building.
◦ Could potentially eliminate heating bills, but can definitely greatly reduce them.
Solar Energy – Power from the Sun
Solar Energy – Power from the SunPassive Solar Heating
Active Solar Heating◦ Energy from the sun is gathered by collectors and
used to heat water or to heat a building.◦ Collectors are usually mounted on a roof and
capture the sun’s energy.◦ Used primarily for water heating.
Solar Energy – Power from the Sun
Photovoltaic Cells◦ Convert the sun’s energy into electricity.◦ Solar cells have no moving parts.◦ Solar cells produce a very small electrical current,
so it cannot meet all of our energy needs.◦ Solar energy production has doubled every four
years since 1985.◦ Provide energy for more than 1 million households
in the developing world.
Solar Energy – Power from the Sun
Solar Energy – Power from the Sun
Wind Farms◦ Large arrays of wind turbines.◦ In CA, supply electricity to 280,000 homes.◦ Wind turbines take up little space, so can be
placed on farms where the land can still be used for other purposes.
Wind Power – Cheap and Abundant
An Underdeveloped Resource◦ Scientists estimate that the windiest spots on
Earth could generate more than ten times the energy used worldwide.
◦ One problem is transporting the electricity from rural areas where it is generated to urban centers where it is needed.
Wind Power – Cheap and Abundant
Biomass fuel◦ Plant material, manure, and any other organic
matter that is used as an energy source.◦ Renewable: wood and dung.◦ Nonrenewable: fossil fuels.
Biomass – Power from Living Things
Methane◦ A byproduct of bacteria decomposing organic
waste.◦ Gas that is used for heating and cooking.◦ Some landfills in the U.S. use the produced
methane to generate electricity.◦ Britain opened the first dung-fired power station
in 2002.
Biomass – Power from Living Things
Alcohol◦ Ethanol can be made by fermenting fruit or
agricultural waste.◦ Corn is a major source of ethanol.◦ Cars and trucks can run on gasohol (a blend of
gasoline and ethanol).
Biomass – Power from Living Things
Hydroelectric energy◦ Energy produced from moving water.◦ Renewable resource that accounts for about 20%
of the world’s electricity.◦ Canada, U.S., Brazil, China, Russia, and Norway
are the major producers (in decreasing order).
Hydroelectricity – Power from Moving Water
The Benefits of Hydroelectric Energy◦ Hydroelectric dams are expensive to build, but
relatively inexpensive to operate.◦ Do not release air pollutants that cause acid
precipitation.◦ Tend to last longer than fossil fuel-powered plants.◦ Provide benefits such as flood control and water
for drinking, agriculture, industry, and recreation.
Hydroelectricity – Power from Moving Water
Disadvantages of Hydroelectric Energy◦ A dam changes a river’s flow.◦ A reservoir floods large areas of habitat above the
dam and ecosystems downstream are disrupted by reduced water flow.
◦ Fertile sediment does not travel as far downriver.◦ If a dam bursts, people may perish and property
may be destroyed.
Hydroelectricity – Power from Moving Water
Geothermal energy◦ Deposits of water in the Earth’s crust are heated
by energy within the Earth.◦ The heat below Earth’s crust can be used to
generate electricity.◦ Geothermal power plants pump heated water or
steam from rock formations and use the water or steam to power a turbine that generates electricity.
◦ The water is returned to the Earth’s crust where it can be heated and used again.
Geothermal Energy – Power from the Earth
Geothermal Heat Pumps: Energy for Homes◦ More than 600,000 homes in the U.S. are heated
and cooled using geothermal heat pumps.◦ Temperature of the ground is nearly constant
year-round.◦ Heat pump is a loop of piping that circulates a
fluid underground. In summer, the ground is cooler. In winter, the ground is warmer.
Geothermal Energy – Power from the Earth
Geothermal Energy – Power from the Earth