Forgot Password?
Home arrow GreeniacsArticles arrow Energy arrow Hydroelectric Power
Written by Andrew Parker   
Share |
Monday, 27 June 2011

Hydroelectric Power
Hydropower, which is energy harnessed from the power of falling water, has been used around the world for thousands of years.1 The first hydroelectric power plant in the United States went online in 1882, and within a few decades hydroelectric power made up approximately 40% of U.S. electricity.2 Hydropower now constitutes only 10% of U.S. electricity production, and nearly 20% of electricity generated around the world.3 In the realm of renewable energy, hydroelectricity is dominant – it is responsible for more than 90% of all energy produced from renewable sources in the United States.4

How Hydroelectricity Works
The mechanics of hydroelectric power production are not too different from those of coal-fired power plants. Both use a source of energy—water in the case of hydropower or coal for traditional energy production—to run an electricity-generating turbine. In the case of coal, steam moves the turbine that powers the generator, while falling water is used for hydroelectric plants.5 Dams must be built in order to create a source of falling water, and thus hydropower. Because gravity plays an important role in the process, dams are located at points where a river drops in elevation. Engineers can control the amount of water that flows through the dam, thereby altering the rate of electricity production.6

http://static.howstuffworks.com/gif/hydropower-plant-parts.gif 7


Advantages of Hydroelectricity
One of the primary advantages of hydroelectric power is its reliance on a renewable resource—water.8 Hydroelectricity requires no fuel to run other than water, which is naturally recycled and replenished through rainfall. As a result, the viability of hydroelectricity is not subject to variations in fuel cost, production and availability.9 The constant supply of water not only solves the fuel problem, it also allows for flexibility and control in levels of electricity production. Whereas solar and wind energy generators are at the mercy of fluctuations in their natural power sources—cloudy or calm days, respectively—hydroelectric plants have a steady flow of water that can even be adjusted in order to provide more power at peak times.10

Another benefit provided by the simple power source is smooth operation. Once they come online, hydroelectric power plants can be mostly automated and require very little attention or maintenance. Indeed, they have proven to be quite long-lasting, with some functioning well past the 50-year mark.11 Hydroelectric power is also the cheapest method of electricity production, largely because of the reasons described above. Hydroelectric plants require minimal resources after their initial construction and none at all to acquire and process energy, which means that they are incredibly efficient to operate.12

Hoover Dam Address
The Hoover Dam, which provides electricity for Nevada, California and Arizona 13


Disadvantages of Hydroelectricity
Hydroelectric power is not perfect. If it was a perfect energy source, there would be no need to debate so many different alternative energy sources! One of the key drawbacks to this type of energy production is that hydroelectric plants only work in specific locations. They must be built on a river, of course, and the site must provide a suitable drop in elevation to run the generator.14 While the costs of operation are minimal, as discussed above, initial construction costs certainly are not. Building a new plant can often be extremely expensive, especially if there is not already an existing dam in place.15 In addition to building the dam, electric generators and transmission lines must also be built.16

Hydroelectric plants tend to run smoothly, but they are not immune to failure. Floods in particular can cause serious problems for a dam, as they can exert much more pressure on the dam than it is intended to withstand. One of the largest failures in history occurred in 1975 at China’s Banqiao Dam. Although the dam was built for extreme levels of flooding, a typhoon in August created flood levels higher than engineers had ever anticipated and caused the dam to collapse. 26,000 people died from the flooding itself, while tens of thousands more died as a result of disease and water contamination in the aftermath of the flood.17 Finally, while hydroelectric power plants do not use fossil fuels, they still produce emissions. This is not due to the electricity generation itself. Rather, the construction of a plant causes flooding in the nearby area, which often kills many plants and trees and leads to the release of methane as they decompose.18 This also leads to loss of biodiversity, another major threat to our environment.

Controversy Surrounding Hydroelectricity
Constructing a new hydroelectric plant is not as simple as finding a good location and starting to build. In recent decades, scientists and environmentalists have been paying close attention to the impacts of hydroelectric power plants on their surrounding environment. One of the most critical issues is the safety of local fish populations. In the Northwestern States, dams have prevented thousands of salmon from traveling upstream to spawn and have also blocked their passage on the way back down.19 John Seebach, director of the Hydropower Reform Initiative, acknowledged the difficulty of the issue: “Hydropower does have pretty significant and serious impacts on rivers… It also provides some pretty significant benefits in terms of power production. So it’s a tricky balance to get those benefits while trying to minimize those impacts.”20

In response to the concerns over disrupting fish populations, the hydroelectric power industry developed ways to protect the passage of fish without interrupting the operation of their generators. Workers at Rocky Reach Dam in Washington, for example, recently completed a nearly $300 million project that included the creation of a “mile-long safe passage tunnel” that will keep the route traversable for the millions of fish that pass through annually.21 Beyond such alterations, there is pressure from advocacy groups and the government for industry leaders to find new ways of minimizing their environmental impact. The Department of Energy recently encouraged “low-head, low-power” facilities—which are smaller units that would be able to produce significant amounts of electricity with a reduced level of environmental impact. 22

In developing nations, the enormous potential of hydroelectric power is being weighed against the potential environmental impacts of new hydroelectric installations. There has been heated debate around new dams in Brazil, Chile, and Laos, among other countries, as environmentalists and downstream residents voice their concerns over the potential consequences—both known and unknown. 23

Hydroelectricity’s Future
There are signs that hydroelectric power will play a growing role in the coming years. The National Hydropower Association aims to double the amount of hydroelectric power generated in the U.S. over the next 15 years, a process made easier by increasing concern over climate change and by the fact that only a small fraction of the nation’s 82,600 dams currently have hydroelectric generators.24 New hydroelectric facilities began running in unprecedented numbers in both 2008 and 2009, suggesting that if the current environmental concerns can be addressed quickly and efficiently, hydroelectric power will have a very bright future.25 Of further interest, wave power from our oceans is an emerging renewable energy source, and has less of an impact on fish and human populations than hydroelectricity.26 We will have to watch and see where the power of water can take us.

Browse all Greeniacs Articles Browse all Greeniacs Guides        Browse all Greeniacs Articles
_______________________________________________________________________________

1http://inventors.about.com/library/inventors/bl_lester_pelton.htm
2Id.
3http://www.fwee.org/abhydro.html
4Id.
5http://ga.water.usgs.gov/edu/hyhowworks.html
6Id.
7http://science.howstuffworks.com/environmental/energy/hydropower-plant1.htm
8http://www.nationalatlas.gov/articles/people/a_energy.html
9http://www.ehow.com/list_6883807_pros-_amp_amp_-cons-hydroelectric-power.html
10Id.
11Id.
12http://environment.nationalgeographic.com/environment/global-warming/hydropower-profile/
13http://www.visitingdc.com/las-vegas/hoover-dam-directions.asp
14http://www.ehow.com/list_6883807_pros-_amp_amp_-cons-hydroelectric-power.html
15Id.
16http://www.nationalatlas.gov/articles/people/a_energy.html
17http://www.britannica.com/EBchecked/topic/1503368/Typhoon-Nina-Banqiao-dam-failure
18http://www.nytimes.com/2011/05/16/business/
global/16iht-green16.html?pagewanted=2&_r=1&ref=hydroelectricpower
19http://articles.latimes.com/2009/jul/27/nation/na-hydro-power27
20Id.
21Id.
22http://topics.nytimes.com/topics/news/business/
energy-environment/hydroelectric-power/index.html
23http://www.nytimes.com/2011/05/16/business/global/
16iht-green16.html?_r=1&ref=hydroelectricpower
24http://articles.latimes.com/2009/jul/27/nation/na-hydro-power27
25http://www.nytimes.com/2011/05/16/business/global/
16iht-green16.html?_r=1&ref=hydroelectricpower
26http://www.greenenergyhelpfiles.com/wavepower.htm




Add your comment
RSS comments

Only registered users can write comments.
Please login or register.

Click here to Register.  Click here to login.
Last Updated ( Tuesday, 28 June 2011 )

SEARCH GREENIACS.COM

Green Facts

  • Recycling 1 million laptop computers can save the amount of energy used by 3,657 homes in the U.S. over the course of a year.

  • One recycled aluminum can will save enough energy to run a 100-watt bulb for 20 hours, a computer for 3 hours, or a TV for 2 hours.

  • Recycling 100 million cell phones can save enough energy to power 18,500 homes in the U.S. for a year.

  • Bamboo absorbs 35% more carbon dioxide than equivalent stands of trees.

  • You’ll save two pounds of carbon for every 20 glass bottles that you recycle.

  • The World Health Organization estimates that 2 million people die prematurely worldwide every year due to air pollution.

  • 77% of people who commute to work by car drive alone.

  • Glass can be recycled over and over again without ever wearing down.

  • Current sea ice levels are at least 47% lower than they were in 1979.

  • Recycling aluminum saves 95% of the energy used to make the material from scratch.

  • Nudge your thermostat up two degrees in the summer and down two degrees in the winter to prevent 2,000 pounds of carbon dioxide from entering the atmosphere.

  • Due to tiger poaching, habitat destruction, and other human-tiger conflicts, tigers now number around 3,200—a decrease in population by about 70% from 100 years ago.

  • You will save 300 pounds of carbon dioxide for every 10,000 miles you drive if you always keep your car’s tires fully inflated.

  • A single quart of motor oil, if disposed of improperly, can contaminate up to 2,000,000 gallons of fresh water.

  • Turning off the tap when brushing your teeth can save as much as 10 gallons a day per person.

  • Recycling for one year at Stanford University saved the equivalent of 33,913 trees and the need for 636 tons of iron ore, coal, and limestone.

  • Every week about 20 species of plants and animals become extinct.

  • In the United States, automobiles produce over 20 percent of total carbon emissions. Walk or bike and you'll save one pound of carbon for every mile you travel.

  • If every U.S. household turned the thermostat down by 10 degrees for seven hours each night during the cold months, and seven hours each weekday, it would prevent nearly gas emissions.

  • Refrigerators built in 1975 used 4 times more energy than current models.

  • Rainforests are being cut down at the rate of 100 acres per minute.

  • An aluminum can that is thrown away instead of recycled will still be a can 500 years from now!

  • Americans use 100 million tin and steel cans every day.

  • Shaving 10 miles off of your weekly driving pattern can eliminate about 500 pounds of carbon dioxide emissions a year.

  • You will save 100 pounds of carbon for each incandescent bulb that you replace with a compact fluorescent bulb (CFL), over the life of the bulb.

  • Less than 1% of electricity in the United States is generated from solar power.

  • A steel mill using recycled scrap reduces related water pollution, air pollution, and mining wastes by about 70%.

  • For every 38,000 bills consumers pay online instead of by mail, 5,058 pounds of greenhouse gases are avoided and two tons of trees are preserved.

  • Americans throw away more than 120 million cell phones each year, which contribute 60,000 tons of waste to landfills annually.

  • Plastic bags and other plastic garbage thrown into the ocean kill as many as 1,000,000 sea creatures every year.

  • 82 percent of greenhouse gas emissions in the U.S. come from burning fossil fuels.

  • A laptop consumes five times less electricity than a desktop computer.

  • States with bottle deposit laws have 35-40% less litter by volume.

  • In California homes, about 10% of energy usage is related to TVs, DVRs, cable and satellite boxes, and DVD players.

  • It takes 6,000,000 trees to make 1 year's worth of tissues for the world.

  • Washing your clothes in cold or warm instead of hot water saves 500 pounds of carbon dioxide a year, and drying your clothes on a clothesline six months out of the year would save another 700 pounds.

  • A tree that provides a home with shade from the sun can reduce the energy required to run the air conditioner and save an additional 200 to 2,000 pounds of carbon over its lifetime.

  • Americans throw away enough aluminum to rebuild our entire commercial fleet of airplanes every 3 months

  • American workers spend an average of 47 hours per year commuting through rush hour traffic. This adds up to 23 billion gallons of gas wasted in traffic each year.