Hydroelectric+Pumped+Storage


 * Hydroelectric Pumped Storage **

__HISTORY:__ Around the world, more than 1 billion people are provided with power by hydropower plants, as they provide about 24% of the world's electricity. [1]

Moving water, for thousands of years, has been the most commonly used source of renewable energy. In towns and cities across the Roman Empire, along with ancient Greece, rivers and streams powered mills as a way to grind corn. In England alone by the 14th century, more than 5,000 mills were producing water. But, during this time period, these mills were never used to generate electricity. It wasn’t until the late 19th century that generating electricity was found as the new use for waterpower. The first hydropower plant in the United States, on the Fox River in Appleton in 1882, began by generating 12 kilowatts (enough to power 250 light bulbs) worth of power. It was this power station that began the trend of hydropower plants producing electricity on rivers. [4]

The first pumped storage plant was known as the Rocky River project. This storage system was built on the Rocky River in Connecticut in 1929. This was the first system to use two separate storage reservoirs, an upper and a lower reservoir, which were situated at different levels.[5]

There are three types of Hydroelectric plants systems: Impoundment, Diversion, and Pumped storage[2]. For this page, we will focus on Pumped Storage.

__PUMPED STORAGE: How Pumped Storage Systems Work:__ Hydroelectric plants uses the energy from water to power a process that turns water into electricity we can use. The water used in this process is first trapped in a dam, or an artificial lake where it will remain until it is needed to produce electricity. This process involves the water flowing from the dam, through a tunnel which leads to a turbine. Once the water reaches the turbine, the force from the water spins a generator. The generator is connected to a transformer, which is where the water is turned into electricity as the generator is spinning.[1] (See diagram below)

(http://science.howstuffworks.com/hydropower-plant1.htm) [1]

__Energy Types:__ The process of Hydroelectric Pumped Energy Storage produces and uses many different forms of energy throughout the process. Before the process begins, the water trapped in the dams waiting to be used is in the form of Stored Energy. The stored energy quickly turns to Kinetic Energy once the penstock (opening to allow water access to the turbine) opens and releases the water. The water has now turned to Kinetic Energy because it is motion [1]. Once the water has entered the turbine and has caused it to begin spinning, the water is turned into Mechanical Energy once it reaches the power station. From there, the water is turned into Electrical Energy in the form we can use. This the electricity that is produced from this process. Because hydroelectric stations are always generating power and electricity, hydroelectric power is a renewable resource, and will not run out any time soon. [2]

The amount of energy generated from Hydroelectric Pumped Storage is determined by two factors: 1) Water Flow: as water flow increases, so does the electricity generated 2) Amount of Hydraulic Head: distance between the water surface and the turbines, as the head increases, so does the electricity generated. The head is largely dependent on the amount of water in the reservoir [1]

(http://www.daviddarling.info/encyclopedia/H/AE_hydroelectric_power.html) [2]

__The Generator:__ The Generator is the part of the Pumping System that converts the water into the electricity we use in our everyday lives There are four main parts to a generator: (http://science.howstuffworks.com/hydropower-plant2.htm) (http://www.powerauthority.on.ca/Storage.asp?StorageID=1609&SiteLanguageID=1) [3]
 * Shaft: holds all the parts together
 * Excitor: sends an electrical current to the rotor
 * Rotor: a series of large electromagnets that spin inside the stator
 * Stator: tightly- wound coil of copper wire

 __Pumped Storage Plant:__ In a conventional hydropower plant, the water from the reservoir flows through the plant, exits and is carried down stream. This is known as a pumped- storage plant. A pumped-storage plant has two main reservoirs:
 * 1) Upper Reservoir: Water flows from this reservoir through the hydropower plant to create electricity
 * 2) Lower Reservoir: Instead of the exiting water flowing into lakes, rivers and streams, it flows into a lower reservoir, where it is kept until it is needed to generate electricity

The water that flows from the lower reservoir to the upper reservoir is pumped through a reversible turbine. This is operated during times where only a small amount of electricity is needed. During high peak times, the water is pumped back down to the lower reservoir to be converted into electricity.

Electricity needs and amounts vary depending on the time of day. When there is a low demand for electricity, the water is pumped up into the upper reservoir to be stored for high demand times. When a large amount of electricity is needed, the water is pumped back down from the upper reservoir to the lower reservoir and then generates electricity. Because an enormous amount of power is needed throughout the world every day, it is extremely important that hydroelectric storage systems store enough water to ensure they will be able to produce enough electricity when needed. If not enough water is stored for electricity production, power failures and outages may occur which could effect large parts of the world. [1]

Because Hydroelectric Pumped Storage systems rely heavily on water, the hydroelectric system greatly depends on the Hydrologic cycle.

Water can be in many different forms throughout the cycle. It can be a liquid, a solid or a gas, and because wind currents are constantly circulating, the water changes state frequently. The sun also generates wind currents and air- current cycles, which drives the Earth's water supply through the Hydrologic cycle.

As the sun heats liquid water, it evaporates into the air. As the water is being evaporated, the air rises due to the heat. As it rises, the air is becoming cooler, and because of the temperature change, the liquid changes to water vapour. It then cools and condenses into water droplets. When enough water droplets have condensed into one area, precipitation then occurs. When the rain falls, some water is trapped in the dams created by the hydroelectric pumping plants. This water will eventually be transferred into electricity. A problem may occur is there is a lack of rain, causing a lack of water to enter the pumping system. This causes a shortage of electricity produced. [1]

__The Hydrologic Cycle:__ (http://science.howstuffworks.com/hydropower-plant3.htm) [1]

__Advantages and Disadvantages of Hydroelectric Power:__ Advantages:
 * Clean fuel source, because it is fueled by water
 * It doesn't pollute the air, for example: the burning of fossil fuels, coal or natural gas greatly pollutes the air
 * Relies on the water cycle, which is powered by the sun, making it a renewable power source
 * Because engineers control the flow of water through the system, hydropower is available as needed
 * Provides benefits in addition to clean electricity: water supply and flood control [2]

Disadvantages:
 * Because of the unnatural dams set up in order for the pumping system to function, fish populations are greatly impacted. Because of the artificial dams, fish are not able to migrate upstream or downstream to spawning grounds or the ocean
 * In order to help the fish swim upstream, fish ladders and elevators or fish trucks are used to help them get upstream. The fish trucks trap the fish, are then carried upstream in their trucks and then released. In order to help fish swim downstream, fish are diverted from turbine intakes by inserting screens or using underwater sounds and lights to distract them
 * Hydropower can impact the quality and flow of the water. This system takes away levels of oxygen in the water which kills aquatic life
 * Hydropower can also be heavily impacted by a drought. Because the system relies so heavily on water, if there is a lack of water, electricity cannot be produced
 * Hydropower stations also impact local environments, local habitats and animals because building large hydropower plants take up an enormous amount of space [2]
 * Building Hydroelectric Pumped Storage facilities is very expensive to build and maintain

An example of a Hydroelectric Pumped Storage System currently in use is the Hoover Dam or also known as the Boulder Dam, in Arizona. The construction of the Hoover Dam began in 1931 and was completed in 1936. The Hoover Dam was built in order to control flooding along the Colorado River. Today, the Hoover Dam is used to produce electricity. [6]

__Bibliography:__

Author Unknown. (2010) Arizona Leisure: Vacation Guide. // Hoover Dam //. Retrieved May 23, 2010, from http://www.arizona-leisure.com/hoover-dam.html

Bonsor, Kevin. (2010).How Stuff Works. // How Hydropower Plants Work // . Retrieved May 23, 2010, from How Stuff Works: http://science.howstuffworks.com/hydropower-plant.htm Darling, David. (2010) The Encyclopedia of Alternative Energy and Sustainable Living. // Hydroelectric Power //. Retrieved May 23, 2010, from http://www.daviddarling.info/encyclopedia/H/AE_hydroelectric_power.html Dennis, J. (2010). Hydroelectric Power. // New Book of Popular Science //. Retrieved May 23, 2010, from Grolier Online http://nbps.grolier.com/cgi-bin/article?assettype=t&assetid=40349 40

Ontario Power Authority (2010) Waterpower. // Technology //. Retrieved May 23, 2010, from http://www.powerauthority.on.ca/Storage.asp?StorageID=1609&SiteLanguageID=1

Smith, Brent. (2008) Hydropower Projects. // The History of Pumped- Storage //. Retrieved May 23, 2010, from Symbiotics http://www.symbioticsenergy.com/projects/pumped/pumped-history.html

[1] http://science.howstuffworks.com/hydropower-plant.htm [2] http://www.daviddarling.info/encyclopedia/H/AE_hydroelectric_power.html [3] http://www.powerauthority.on.ca/Storage.asp?StorageID=1609&SiteLanguageID=1 [4] http://nbps.grolier.com/cgi-bin/article?assettype=t&assetid=4034940 [5] http://www.symbioticsenergy.com/projects/pumped/pumped-history.html [6] http://www.arizona-leisure.com/hoover-dam.html