How Hydropower Plants Work

Around the globe, hydropower plants generate nearly 24 percent of the world's electricity and supply over a billion people with power. The world's hydropower plants generates a combined amount of 675,000 megawatts, the energy equivalent of 3.6 billion barrels of oil, according to the National Renewable Energy Laboratory. There are over 2,000 hydropower plants operating in the United States, making hydropower the country's biggest renewable energy source.

The Enormous Power of Water

Watching a river flow, it is amazing to know amount of force it drags along. Have you ever been water rafting, then you must have experienced a small bit of the water power. Rapids are created as a river,dragging along a huge quantity of water downhill,forcefully through a narrow passageway. As the river is forces it way through small opening, its flows rapidly. Floods are typical examples of the huge amount force a large volume of water can exert.

Hydropower plants utilize water's energy and apply simple mechanics to transform the energy to electricity. Hydropower plants are normally based on a simple concept of water flowing forcefully through a dam turns a turbine, which turns a generator.

The following are basic components of a conventional hydropower plant:
1.Dam: Nearly all hydropower plants depend on a dam that holds back water, creating a large reservoir. Most times, the reservoir is used as a recreational lake, such as Lake Roosevelt at the Grand Coulee Dam in Washington State.

2.Intake : Gates on the dam open and gravity draws the water via the penstock, a pipeline leading to the turbine. Water pressure builds up as it flows through this pipe.

3.Turbine: The water strikes and turns the huge blades of the turbine, which are fitted to the generator above it using a shaft. The typical type of turbine for hydropower plants is the Francis Turbine, resembles a large disc,having curved blades. A turbine weighing up to 172 tons and can rotate at 90 revolutions per minute (rpm).

4.Generators: As the turbine blades rotates, so does a combination of magnets within the generator. Giant magnets rotate close to copper coils, generating alternating current (AC) by making electrons move.

5.Transformer: The transformer within the powerhouse retrieves the AC and transforms it to higher-voltage current.

6.Power lines : Out of every power plant come four wires: the three phases of power being produced at once with an additional neutral or ground common to all three.

7.Outflow: Used water is moves through pipelines, known as tailraces, and flows back to the river downstream.

The water in the reservoir is viewed as stored energy. When the gates are opened , the water flowing via the penstock transforms to kinetic energy because it is in motion. The quantity of electricity generated depends on several factors. Two of the most common factors are the volume of water flow and the level of hydraulic head. The head refers to the distance between the water surface and the turbines. As the head and flow increases, so does the electricity generated. The head normally depends on the quantity of water in the reservoir.

Hydropower BackStory

Use of hydropower reach its peak in mid-20th century, but the idea of using water to power machinery can be traced back to thousands of years. A hydropower plant is basically an oversized water wheel. About 2,000 years ago, the Greeks were said to have employed water wheel for grinding wheat to flour.These ancient water wheels, were similar to turbines of today, spinning as a stream of water hits the blades. The gears of the wheel ground the wheat into flour.

Pumped-Storage Plants
Another type of hydropower plant is known as the pumped-storage plant. In a normal hydropower plant, the water from the reservoir flows through the plant, leaves and is taken down stream. A pumped-storage plant has two reservoirs:
1.Upper reservoir :Similar to a typical hydropower plant, a dam creates a reservoir. The water in the reservoir flows through the hydropower plant to generate electricity.

2.Lower reservoir - Water leaving the hydropower plant flows into a lower reservoir instead of re-entering the river and flowing downstream.

Using a reversible turbine, the plant is able to pump water back to the upper reservoir. This is quickly done in off-peak hours. Technically, the second reservoir refills the upper reservoir. By pumping back water into the upper reservoir, the plant now has enough water to generate electricity during times of high consumption.

The Generator

The main part of the hydroelectric power plant is the generator.All hydropower plants have several types of these generators.

The generator, generates electricity and the bases of generating electricity in this mode is to rotate a set of magnets within coils of wire. This process moves electrons,that produces electrical current.

The Hoover Dam with a total of 17 generators, each of which generates up to 133 megawatts. The total capacity of the Hoover Dam hydropower plant peaks at 2,074 megawatts. Each generator consists of some basic components:
1. Shaft
2. Excitor
3. Rotor
4. Stator

As the turbine rotates, the excitor sends electric current to the rotor. The rotor consists of a set of large electromagnets that spins inside a tightly-wound coil of copper wire, known as the stator. The magnetic field between the coil and the magnets generates an electric current.

In the Hoover Dam, a current of 16,500 amps passes from the generator to the transformer, where the current is multiplied to 230,000 amps before being transmitted.

Hydrologic Cycle

Hydropower plants take advantage of a naturally occurring, continuous process -- the process that makes rain to fall and rivers to rise. Day by day, our planet loses a little amount of water via the atmosphere as ultraviolet rays tear water molecules apart.Simultaneously, new water comes out from the inner part of the Earth via volcanic activity. The quantity of water created and the amount of water lost is all most the same.

At any point in time, the globe's total volume of water,exist in several forms. It can be liquid,in form of oceans, rivers and rain; solid,in form of glaciers; or gaseous,in form of the invisible water vapor in the air. Water changes it states as it moves round the globe by wind currents. Wind currents are generated by the heating activity of the sun. Air-current cycles are generated by the sun shining more at the equator than at any other place on the globe.

Air-current cycles powers the Earth's water supply via a cycle of its own,known as the hydrologic cycle.As the sun heats up liquid water, the water evaporates,turning into vapor in the air. The sun also heats up the air, making the air to increase in the atmosphere. The air becomes it rises higher up, condensing into water droplets.After enough droplets accumulate in a particular area, the droplets become heavy enough to fall back to the Earth as precipitation.

The hydrologic cycle is quite important to hydropower plants because they rely on water flow. If there is a lack of rain near the plant, water will not accumulate upstream. If no water collects up stream, less water flows through the hydropower plant and less electricity is generated.

Notable Large Dams
1.The largest hydroelectric power plant in the world is the Itaipu power plant,owned by Brazil and Paraguay. Itaipu produces peak power of 12,600 megawatts.

2.The second largest hydroelectric power plant is the Guri power plant,on Caroni River in Venezuela. It produces peak power of 10,300 megawatts.

3.The largest U.S. hydroelectric power plant is the Grand Coulee power station on the Columbia River in Washington State. It produces peak power of 7,600 megawatts and is being upgraded to produce peak power of 10,080 megawatts. 

Hydroelectric Footwear 
The basic concept of hydropower is to harness the power of a liquid in motion to turn a turbine blade. Normally, a large dam has to be built in the middle of a river this purpose. A recent invention is taking advantage of the concept of hydropower on a smaller scale to generate electricity for portable electronic devices.

An inventor names Robert Komarechka of Ontario, Canada,came up with the concept of inserting miniature hydropower generators within the soles of shoes. He believes these miniature turbines can generate enough electricity to power any gadget. In May 2001, Komarechka registered a patent for his unique foot-powered device.

There's a very basic principle to how we walk: The foot falls heel-to-toe during each step. As your foot lands on the ground, force is brought down through your heel. When you prepare for your next step, you roll your foot forward, so the force is transferred to the ball of your foot. Komarechka apparently noticed this basic principle of walking and has developed an idea to harness the power of this everyday activity.

There are five parts to Komarechka's "footwear with hydroelectric generator assembly," as described in its patent:
  • Fluid - The system will use an electrically conductive fluid. 
  • Sacs to hold the fluid - One sac is placed in the heel and another in the toe section of the shoe. 
  • Conduits - Conduits connect each sac to a microgenerator. 
  • Turbine - As water moves back and forth in the sole, it moves the blades of a tiny turbine. 
  • Microgenerator - The generator is located between the two fluid-filled sacs, and includes a vane rotor, which drives a shaft and turns the generator.
As a person walks, the compression of the fluid in the sac located in the shoe's heel will force fluid through the conduit and into the hydroelectric generator module. As the user continues to walk, the heel will be lifted and downward pressure will be exerted on the sac under the ball of the person's foot. The movement of the fluid will rotate the rotor and shaft to produce electricity.

An exterior socket will be provided to connect wires to a portable device. A power-control output unit may also be provided to be worn on the user's belt. Electronic devices can then be attached to this power-control output unit, which will provide an steady supply of electricity.

"With the increase in the number of battery-powered, portable devices," the patent reads,"there is an increasing need to provide a long-lasting, adaptable, efficient electrical source." Komarechka expects that his device will be used for powering portable computers, cell phones, CD players, GPS receivers and two-way radios.

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