Introduction

This is my seventh grade ALM final project on Alternative Energy Resources. For my project I will be covering wind energy, water power, and solar energy. For the wind power section, I would like to learn how wind is made, what a wind farm is, and the disadvantages. For solar energy, I would like to learn how we get energy from a simple little panel, some cool facts about it, and the disadvantages. And finally, for Hydropower, I'd like to learn the different types of dams, how they produce electricity, and the disadvantages. I know that these aren't all the alternative energy sources out there, but they're some of the biggest ones. Well, enjoy!

Wind Energy

What is Wind?

Wind is simple air in motion. It is caused by the uneven heating of the earth’s surface by the sun. Since the earth’s surface is made of different types of land and water, it absorbs the sun’s heat at different rates.
During the day, the air above the land heats up more quickly than the air over water. The warm air over the land expands and rises, and the heavier, cooler air rushes in to take its place, creating winds. At night, the winds are reversed because the air cools more rapidly over land than over water. In the same way, the atmospheric winds that circle the earth are created because the land near the earth's equator is heated more by the sun than the land near the North and South Poles.
Wind_energy.gif
Creation of WInd

Today, wind energy is mainly used to generate electricity. Wind is called a renewable energy source because the wind will blow as long as the sun shines.

Wind Farms

Wind farms are created when wind turbines are placed in the same location so they can produce large amounts of electricity. Due to rising energy prices and the result from the search for more alternatives, there are now thousands of wind farms in many countries around the world.
external image windaug012007.jpg

Disadvantages

Wind power can be very useful, but there are some disadvantages to it that you should know about, too.
First of all, the strength of the wind is not constant and can vary from zero to storm force. This means that wind turbines do not produce the same amount of electricity all the time. There will be times when they produce no electricity at all.
Another reason is that many people feel that the countryside should be left untouched, without these large structures being built. The landscape should be left in its natural form for everyone to enjoy.
Also, wind turbines are noisy. Each one can generate the same level of noise as a family car travelling at 70 mph.
A fourth reason is that a lot of people see large wind turbines as unsightly structures and not pleasant or interesting to look at. They disfigure the countryside and are generally ugly.
Also, large wind farms are needed to provide entire communities with enough electricity. For example, the largest single turbine available today can only provide enough electricity for 475 homes, when running at full capacity. How many would be needed for a town of 100,000 people?
Lastly, wind turbines can be pretty dangerous. just watch the videos below!





Solar Energy

How we get Energy

The sun has produced energy for billions of years. Solar energy is the sun’s rays (solar ) that reach the earth.
Solar energy can be converted into other forms of energy, such as heat and electricity. Today, people use the sun's energy for lots of things.
Solar energy can be converted to thermal energy and used to heat water for use in homes, buildings, and/or swimming pools and to heat spaces, inside greenhouses, homes, and other buildings.
Solar energy can be converted to electricity in two ways: Photovoltaic (Pv devices) or solar cells and Solar Power Plants.
Pv devices change sunlight directly into electricity. These devices are often used in remote locations that aren't connected to an electric grid. You can also find them in watches, calculators, and light up road signs.
Solar Power Plants indirectly generate electricity when the heat from solar thermal collectors is used to heat a fluid which produces steam that is used to power a generator.
external image solar_panel.jpg

Percentages

Research shows that an average household with an electric water heater spends about 25% of its home energy costs on heating water.
Solar water heaters offered the largest potential savings, with solar water-heater owners saving as much as 50% to 85% annually on their utility bills over the cost of electric water heating.You can expect a simple payback of 4 to 8 years on a well-designed and properly installed solar water heater. (Simple payback is the length of time required to recover your investment through reduced or avoided energy costs.)
You can expect a simple payback of 4 to 8 years on a well-designed and properly installed solar water heater. (Simple payback is the length of time required to
recover your investment through reduced or avoided energy costs.)
Solar water heaters do not pollute. By investing in one, you will be avoiding carbon dioxide, nitrogen oxides, sulfur dioxide, and the other air pollution and wastes created when your utility generates power or you burn fuel to heat your household water.

Disadvantage

Solar cells/panels, etc. can be very expensive.
Solar power cannot be created at night.
Very diffuse source means low energy production--large numbers of solar panels (which means larger land areas) are required to produce useful amounts of heat or electricity.
Only areas of the world with lots of sunlight are suitable for solar power generation.



Hydro-power

Different Types of Dams

Since the first large-scale dam was built in Egypt more than 5,000 years ago, engineers have devised various types of dams to withstand the forces of a raging river.

Arch Dams

Arch dams are good for narrow, rocky locations. They are curved, and the natural shape of the arch holds back the water in the reservoir. Arch dams, like the El Atazar Dam in Spain, are thin and require less material than any other type of dam.

Sneak a peek at the forces that affect arch dams.
El Altazar Dam
El Altazar Dam

Buttress Dams

Buttress dams may be flat or curved, but one thing is certain: a series of supports, or buttress, brace the dam on the downstream side. Most buttress dams, like the Bartlett Dam in Arizona, are made of reinforced concrete.

Check out the forces that affect buttress dams.
Bartlett Dam
Bartlett Dam

_
_
Embankment dams

Embankment dams are the most commonly built dams in the United States. They are massive dams made of earth and rock. Like gravity dams, embankment dams rely on their heavy weight to resist the force of the water. But embankment dams are also armed with a dense, waterproof core that prevents water from seeping through the structure. Tailings dams -- large structures that hold back mining waste -- are a type of embankment dam.

Check out the forces that affect embankment dams.
New Waddell Dam
New Waddell Dam


Gravity Dams


Gravity Dams are massive dams that resist the thrust of water entirely by their own weight. Most gravity dams, like the Grand Coulee Dam in Washington, are expensive to build because they require so much concrete. Still, many people prefer its solid appearance to the thinner arch and buttress dams.

Take at look at the forces that affect gravity dams.


Grand Coulee Dam
Grand Coulee Dam


All dams -- whether they're embankment, buttress, arch, or gravity -- must be maintained as they get older. Without proper maintenance, spillways can clog and concrete can crack. Some dams are even removed because they block the migration of fish.


How we get Energy (Hydropower) from Dams


Understanding the water cycle is important to understanding hydropower. In the water cycle, solar energy heats water on the surface, causing it to evaporate. This water vapor condenses into clouds and falls back onto the surface as precipitation. The water flows through rivers back into the oceans, where it can evaporate and begin the cycle all over again.
Water cycle, from http://www.eia.doe.gov/kids/energyfacts/sources/renewable/water.html#howhydroworks
Water cycle, from http://www.eia.doe.gov/kids/energyfacts/sources/renewable/water.html#howhydroworks
Mechanical energy is derived by directing, harnessing, or channeling moving water. The amount of available energy in moving water is determined by its flow or fall.Swiftly flowing water in a big river, like the Columbia River , carries a great deal of energy in its flow. So, too,with water descending rapidly from a very high point, like Niagara Falls. In either instance, the water flows through a pipe, or penstock, then pushes against and turns blades in a turbine to spin a generator to produce electricity. In a run-of-the-river system, the force of the current applies the needed pressure, while in a storage system, water is accumulated in reservoirs created by dams, then released when the demand for electricity is high. Meanwhile, the reservoirs or lakes are used for boating and fishing, and often the rivers beyond the dams provide opportunities for whitewater rafting and kayaking.
How a Hydropower Dam works, from http://www.eia.doe.gov/kids/energyfacts/sources/renewable/water.html#howhydroworks
How a Hydropower Dam works, from http://www.eia.doe.gov/kids/energyfacts/sources/renewable/water.html#howhydroworks

The Hoover Dam, one of the dams that produces hydropower completed in 1936 on the Colorado River between Arizona and Nevada, created Lake Mead, a 110-mile-long national recreational area that offers water sports and fishing in a desert setting.











Disadvantages


Dams are extremely expensive to build and must be built to a very high standard.

The high cost of dam construction means that they must operate for many decades to become profitable.

The flooding of large areas of land means that the natural environment is destroyed.

People living in villages and towns that are in the valley to be flooded, must move out. This means that they lose their farms and businesses. In some countries, people are forcibly removed so that hydropower schemes can go ahead.

The building of large dams can cause serious geological damage. For example, the building of the Hoover Dam in the USA triggered a number of earthquakes and has depressed the earth’s surface at its location.

Although modern planning and design of dams is good, in the past old dams have been known to be breached (the dam gives under the weight of water in the lake). This has led to deaths and flooding.

Dams built blocking the progress of a river in one country usually means that the water supply from the same river in the following country is out of their control. This can lead to serious problems between neighboring countries.

Building a large dam alters the natural water table level. For example, the building of the Aswan Dam in Egypt has altered the level of the water table. This is slowly leading to damage of many of its ancient monuments as salts and destructive minerals are deposited in the stone work from ‘rising damp’ caused by the changing water table level.


My Resources