1. SB p.80 ex.1 (10-15 sent)
2. Read and translate
Common
Alternative Energy Sources
Reduce Toxins, Preserve
Natural Resources With Renewable Energies
Updated April 20, 2017
There are many reasons the world is looking for alternative energy sources
in an effort to reduce pollutants and greenhouse gases. Alternative or
renewable energy sources show significant promise in helping to reduce the
amount of toxins that are by-products of energy use and help preserve many of
the natural resources that we currently use as sources of energy.
To understand how alternative energy use can help preserve the delicate
ecological balance of the planet, and help us conserve the non-renewable energy
sources like fossil fuels, it is important to know what type of alternative
energy is out there.
Let's take a look at some of the most common sources available.
1. Wind Power
Wind energy harnesses the power of the wind to propel the blades of wind
turbines. The rotation of turbine blades is converted into electrical current
by means of an electrical generator. In the older windmills, wind energy was
used to turn mechanical machinery to do physical work, like crushing grain or
pumping water. Wind towers are usually built together on wind farms. Now, electrical currents are harnessed by large-scale wind farms that are used by national electrical grids as well as small individual
turbines used for providing electricity to isolated locations or individual
homes. In 2005, worldwide capacity of wind-powered generators was 58,982
megawatts, their production making up less than 1 percent of worldwide
electricity use.
Pros
- Wind power produces no pollution that can
contaminate the environment, Since no chemical processes take place, as in
the burning of fossil fuels, there are no harmful by-products left over.
- Since wind generation is a renewable source of
energy, we will never run out of it.
- Farming and grazing can still take place on land
occupied by wind turbines which can help in the production of biofuels.
- Wind farms can be built off-shore.
Cons
- Wind power is intermittent. Consistent wind is
needed for continuous power generation. If wind speed decreases, the
turbine lingers and less electricity is generated.
2. Solar Power
Solar energy is used commonly for heating, cooking, the production of electricity, and
even in the desalination of seawater. Solar power works by trapping the sun's rays into solar cells where this sunlight is
then converted into electricity. Additionally, solar power uses sunlight that hits solar thermal panels to convert sunlight to heat
water or air. Other methods include using sunlight that hits parabolic mirrors
to heat water (producing steam), or simply opening blinds or window shades to
allow entering sunlight to passively heat a room.
Pros
- Solar power is a renewable resource. As long as
the Sun exists, its energy will reach Earth.
- Solar power generation releases no water or air
pollution because there is no chemical reaction from the combustion of
fuels.
- Solar energy can be used very efficiently for
practical uses such as heating and lighting.
- The benefits of solar power are seen frequently
to heat pools, spas, and water tanks all over.
Cons
- Solar power does not produce energy if the sun is
not shining. Nighttime and cloudy days seriously limit the amount of
energy produced.
- Solar power stations can be very expensive to
build.
3. Geothermal Energy
Geothermal literally means "earth heat." Geothermal energy
harnesses the heat energy present underneath the Earth. Hot rocks under the
ground heat water to produce steam. When holes are drilled in the region, the
steam that shoots up is purified and is used to drive turbines, which power
electric generators.
Pros
- If done correctly, geothermal energy produces no
harmful by-products.
- Once a geothermal plant is built, it is generally
self-sufficient energy wise.
- Geothermal power plants are usually small and
have little effect on the natural landscape.
Cons
- If done incorrectly, geothermal energy can
produce pollutants.
- Improper drilling into the earth can release
hazardous minerals and gases.
- Geothermal sites are prone to running out of
steam.
4. Hydroelectric Energy
Hydroelectric power comes from the potential energy of dammed water driving
a water turbine and generator.
Another variation is to make use of water's kinetic energy or undammed sources such as tidal power. Hydropower works
by harnessing the gravitational descent of a river that is compressed from a
long run to a single location with a dam or a flume. This creates a location
where concentrated pressure and flow of water can be used to turn turbines or
water wheels to drive an electric generator. Electric generators powered by
hydropower can be run backward as a motor to pump water back up for later use.
Pros
- Water can be accumulated above the dam and released
to coincide with peaks in demand. So, unlike other types of power
stations, hydroelectric power stations can promptly increase to full
capacity.
- Electricity can be generated constantly, because
there are no outside forces, unlike other forms of alternative energy,
which affect the availability of water.
- Hydroelectric power produces no waste or
pollution since there is no chemical reaction to produce power.
- Water used for hydropower can be reused.
Cons
- Dams can be very expensive to build.
- There needs to be a sufficient and powerful
enough supply of water in the area to produce energy.