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Hydropower!!!!!!!

Emma Khazzam!!

Académie de la Capitale!!

Mme Neena!!

11th grade, Physics!!

The 29th of January, 2014

Water is life. Nothing could survive with out it. It is found everywhere, from the oceans below to the air around us. Water is vital to our existence. Two thirds of our bodies are composed of water. Not only is water an essential part of life, but it is an amazing source of power. Harnessing power from water has been an enormous benefit to the human race. Sixty percent of Canada’s electricity comes from Hydropower.  It is 1

the most efficient and least expensive method of creating electricity in the United States. Water’s power can be used to make electricity anywhere in the world, as long as there is falling water. Hydropower is an extremely successful way of generating electricity.!!

How do we get energy from water? All energy comes from one source; the sun. When the heat of the sun evaporates the water from oceans, it gets transformed into vapour which rises up against gravity. This is the beginning of the hydrologic cycle (figure 1). The vapour condenses into clouds and when the clouds get too heavy, gravity forces rain or snow to fall. The rain returns to the earth and flows into tiny rivulets and streams, then into large rivers, and finally into oceans, and the cycle begins again. During the hydrologic cycle, the force of the water after it falls and flows until it reaches the ocean, can exceed several million horsepower. This is the force humans attempt to harness when they build hydroelectric power plants. !!

Electricity is the flow of electrons in a conductor or metal wire. This is called a current of electricity. Electrons have tiny negative changes which create a magnetic force, but electrons can move if you "push" them with a magnet, which is how the generator in hydropower plants works. A still lake might have potential energy but it can not generate power until the water moves.!!

How does hydroelectricity work? The force of gravity causes rain and snow to fall, streams to gush, and rivers to flow, as seen in the hydrologic cycle. Hydroelectricity extracts the energy from the water as it moves and flows by. Simply, hydroelectricity works by using energy from moving water to turn a turbine, which spins a electric generator, which is the motor that produces electricity. The turbine converts water power into rotational power, then the generator converts the rotational power into electrical power. Power is never created, it is only converted. !!

Humans have been using contraptions, such as waterwheels, to contain water power for hundreds of years. The amount of power that can be collected depends on three things: the head, the flow and the tubing design. Without the head and the flow, water power can not be produced. The flow is the water quantity, measured in volume per second or gallons per minute. The head is the difference in elevation between the water intake and the turbine, expressed in meters, if measuring the vertical elevation, or PSI (pounds per square inch) if measuring the pressure. If the vertical drop is higher, then the pressure will increase. The pressure from the falling water spins the turbines at a high speed, which generates power. If the pressure of the water increases, the amount of power will grow. Pressure is added by putting the water in a container, such as a tube or a reservoir, and the weight of the water applies pressure on the bottom of

� "Backgrounder Water Power." 1

the container. When an opening is placed at the bottom of the container, the water will cascade downwards. If turbines are at the bottom, then the water will turn the turbines at a high speed and generate electricity. There are two common ways of harnessing the energy from hydropower; dams and run-of-river.!!

A dam is a wall of water-tight material built across a river to block the flow of the water (figure 2). They are used to raise the head, which causes the pressure to increase. When the water from the reservoir is released, it flows through a pipe called a penstock which carries the water to the turbine. The water rushes around the turbines causing them to turn. As the turbines spin, the generator turns, converting the kinetic energy from the water into electricity. The electricity goes though transmission lines that connect our homes and business providing us with hydroelectricity. !!

Run-of-river, micro-hydro or low-impact facilities (figure 3) are more environmentally friendly then dams. Run-of-river hydro uses water that is available at the moment that is it available. These low-impact facilities work by diverting some of the river's flow, carrying it to a turbine, then returning the water downstream. Small dams are made to ensure that the intake of the penstock is always underwater. Using the force of gravity, the penstocks carry the water to the turbines. As the turbines spin, energy is converted and electricity is sent through transmission lines. After the water flows through the turbine, a channel returns it to the river of origin. Run-of-river centres are simple to instal and maintain, and produce important local jobs because the local people can maintain their own systems. There are many benefits to run-of-river facilities, as there are many benefits of hydropower over all.!!

The benefits of hydropower are numerous. One of the most important advantage is that hydroelectricity is a renewable energy source. It uses the energy from the movement of the water to produce electricity, without reducing the quantity of water. The greenhouse gas emissions are ultra-low in Canadian hydropower. The hydro facilities are durable, some have even lasted more than 100 years! It is extremely efficient. In modern stations 95% of hydropower can be converted into electricity.  The water used 2

to turn the turbines in dams are stored in reservoirs, which means that they can produce electricity on demand. It is cost effective and certain, thus it can provide long-term price stability, which is affordable and attractive to consumers. Hydropower is renewable and abundant.!!

Hydropower is an extremely clean source, but it has disadvantages. Initial, short term capital costs for building hydropower projects can be very high. Only governments and large corporations can afford to build them. The impact on the ecology can be large. Upstream from the dam, areas are flooded and natural migrations can be blocked. Engineers have tried to help the migration of fish by building fish ladders which are narrow artificial streams that flow next to the power plant to bypass it. Hydro can also affect the area downstream, causing the water to rise and fall drastically on a daily basis and reducing the amount of organisms that can live in the region. When an area is

� (MJ Whiticar, University of Victoria)2

flooded for a reservoir, the trees get covered in water. Trees contain a small amount of mercury, and when they are flooded, some of the mercury seeps out of the tree. The mercury is absorbed by small organisms, which get eaten by larger creatures, which then get eaten by bigger animals and so on until a large animal at the top of the food chain contains an abnormal amount of mercury. The mercury can potentially harm the animal. The reservoirs from dams create new, human-made lakes that can alter erosion patterns, natural acoustics and local scents. Though by itself electricity is clean, how it is generated is not as clean.!!

Compared to other energy sources, hydropower is exceptional in many ways (figure 4). After the initial high capital costs, the operating costs are low and since it is flexible, hydro is more efficient and economical than other sources. The amount of greenhouse gases, or GHG, is minimal whereas other power plants that use coal, gas or oil, have much larger GHG. For example, if you use, on average, 10 000 kWh per month. If your electricity comes from coal, 200 000 pounds of CO2 would be emitted to create the electricity for you personally. If your electricity came from hydropower, the CO2 emissions would be zero! Even after the sun goes down and the wind stops blowing, hydro power keeps on generating electricity.!!

Water is awe inspiring, renewable and powerful. Its power is so abundant that humans are able to harness some of its power for their own purposes. Hydropower has its benefits and its disadvantages, but “when water is harnessed with patience, skill and respect, it is indeed a precious and inexhaustible natural resource.”  3

� Antoine de Saint-Exupéry, French author and aviator3

Figure 1

Figure 2

Figure 3

Figure 4

Bibliography:!!Websites:!"Backgrounder Water Power." re-energy. Green Learning. Web. 21 Jan 2014. <http://www.re-energy.ca/docs/water-power-bg.pdf>.!!Woodward, Richard. "How Dams Work." That Dam Site. N.p., n.d. Web. 27 Jan 2014. <http://members.optusnet.com.au/~engineeringgeologist/page5.html>.!!"10 REASONS FOR PROMOTING THE HYDROELECTRICITY." . ITAIPU. Web. 29 Jan 2014. <http://www.itaipu.gov.br/en/energy/10-reasons-promoting-hydroelectricity>.!!"Run-of-River Hydropower in BC." . Watershed Watch Salmon Society Coquitlam, British Columbia, n.d. Web. 29 Jan 2014. <http://www.watershed-watch.org/publications/files/RoR-CitizensGuide.pdf>.!!"Hydro Systems Overview." The Guide to Hydropower. Canyon Industries, n.d. Web. 29 Jan 2014. <http://www.canyonhydro.com/guide/index.html>.!!"How Hydropower Works." Why Hydro Power. N.p., n.d. Web. 29 Jan 2014. <http://www.whyhydropower.com/HydroTour2a.html>.!!MJ Whiticar, University of Victoria, . "Large-Hydro." . Energy Bc, n.d. Web. 29 Jan 2014. <http://www.energybc.ca/profiles/largehydro.html!!Museum:!Canada Science and Technology Museum!!Books:!Hydro Québec, . Electricity from the power station to the home. 3rd quarter. Canada: !2004. Print.!!Davis, Scott. Microhydro. Canada: New Society Publishers, 2003. Print.!!Parker, Steve. Water Power. USA: Gareth Stevens Publishing, 2004. Print.