RENEWABLE ENERGY SOURCES: AN OVERVIEW
-Wind energy is a clean and renewable source of electricity.
-Through uneven heating of the atmosphere by the sun and the rotation of the earth on its axis, winds are created. Wind energy is captured by huge turbines that propel our skies. These turbines convert the winds kinetic energy into mechanical power. Most of the mechanical power is then converted to electricity by a generator and is used to power homes, factories, and schools.
- In order for wind energy to be effective, proper winds and land features are crucial
This diagram displays the average wind power found across the U.S.
How is Wind Energy Measured?
and land use exclusions for wind class of 3 and higher.)
Wind turbines convert wind energy into electricity, contrary to how a fan works. Fans use electricity to create winds. Huge propeller blades whip around in the air to create quite an amazing sight. There are two basic types of turbines, horizontal-axis and vertical-axis, composed of three basic parts. The tower, which supports the entire craft, the rotor, converts winds into a rotation shaft energy, and the drive train, where you find the gears and generator. Wind passes over the surfaces of the blade. It passes by the longer side of the blade quicker than the other. Pressure is created on both sides of the blade, the differing pressures causes a force called aerodynamic lift which in turn causes the rotation of the propellers. Another force called “drag” is created through this process. It impedes the “lift” force and through the ingenuity of the blades and craft, “drag” is sought to be minimized for optimal output.
Turbines are mostly found in groups called wind farms in which all
the power produced is sent to a “mother” plant and the electricity
is distributed to consumers. The size of the turbines is directly correlated
to the amount of energy it can produce. For example, larger turbines
with a propeller span the size of a football field can power 1,400 homes.
A smaller turbine, with propeller span of about 17 feet can supply electricity
for a small business. There is a simple way to calculate a rough estimate
of how many households a turbine can supply. Using this calculation,
one can assume that a typical turbine (660 kW) can provide for 400 homes.
Great Wind energy animation: http://www.eere.energy.gov/consumerinfo/ (click on how a wind turbine works)
Positives of Wind Energy:
-Wind is renewable, and no matter how much wind we use to supply energy, it will always remain
-Wind energy is clean, non-polluting and free as well
-Turbines can reduce emissions of carbon dioxide (leading greenhouse gas), sulfur dioxide, and nitrogen oxides. Approximately 1.5 pounds of carbon dioxide are emitted per kW when fuel is used for energy (based on U.S. average fuel mix). An average wind turbine will prevent the three million pounds of carbon dioxide emissions. WOW!
-A single 750 kW turbine will stop as much carbon dioxide emissions as 500 acres of forest could.
-Water Usage: According to California Energy Commission, wind consumes 0.004 L/kW, nuclear energy consumes 2.3 L/kW, and coal consumes 1.9 L/kW. The only consumption of water by wind is used to clean the turbines. It uses less than 1/1600 as much water than nuclear does.
-Energy Balance, the comparison of energy used to manufacture vs. energy produced by the source. Often measured in “payback time”, which is the time necessary to produce the same amount of energy it took to manufacture the product. Wind energy’s average “payback time” is three to five months. It will produce more than thirty times more energy in its ten to twenty year reliability than used to produce the craft.
Negatives of Wind Energy:
-Noise is a concern of those near the wind energy sites. Most of the noise is masked by the wind itself, but they can still be heard.
-Visual Impact: Turbine locations are normally in open landscape, making them highly visible. Some feel that this is a problem, others do not
-concerns is the avian and bat mortality. These creatures fly into the rotors of the turbines. Federally protected birds and bats near wind farms have raised awareness with the fish and wildlife agencies. Industries and their engineers have been busy however to improve these issues through more proper siting, insulated materials, and research on landscape and the organisms living there
-Winds aren’t always there when you need them...
-Where to put the turbines? Use of remote land, agriculture, etc...
The most recent advancement in wind technology is already well on its way, off-shore turbines. Winds are significantly stronger and much steadier at sea and if we can capture this energy, they will be much more effective than the on-land turbines. The largest proposal in the U.S. is near Cape Cod where the water is relatively shallow and far enough away from the coast for the turbines to be effective. There are not very many sites in the U.S. in consideration because that depth of the water increases the cost of the structures. Other concerns include disruptions with shipping, fishing and marine life. As the demand for renewable resource increases, these technologies will be taken into more consideration.