PROS AND CONS OF HYDROPOWER DAMS
NOT SO FREE ENERGY FROM FLOWING WATER
Debates about hydropower dams focus on the flooding of millions of acres to provide electrical power. To some, both the dollar cost and environmental price of hydropower have been unacceptable.
But dams are the basis of most hydropower used today. While hydropower dams are controversial, they do work. Dam projects to harness the massive power of the rivers of the world will continue for decades. Each of these projects will need to address a number of public concerns.
[Note: much of the information used in this section comes from the
World Commission on Hydropower Dams
. Herein referred to as the WCD. The World Commission on Dams is a body of the United Nations.]
ENVIRONMENTAL FRIENDLINESS -
On the negative side, large hydropower dams flood a lot of land. They displace wildlife and people. Conservationists and sport fishermen alike have legitimate concerns over large fish kills when turbines are running. And there are more problems.
Large dams alter the natural flow of rivers and cause problems with migrating fish. Other fish that spawn in moving water find little water flow in areas impounded by dams.
New Scientist - Hydropower’s Dirty Secret
report documents claims that hydropower dams in forested areas can actually produce more greenhouse gasses than fossil fuel plants of the same output. If vegetation is left in place when the lake floods, the dead material will emit methane as it decays. This process can go on for years, indefinitely in areas that are intermittently flooded and dried. The report also states that many hydropower dams also eliminate vast forested areas that had been removing CO2 from the atmosphere.
But there is a good side. Hydropower dams create recreation areas and large fish habitats. Many aquatic species have no problem adapting to impounded waters. And the power generated by flowing water produces no carbon dioxide or pollutants.
Though many acres of ground are sacrificed when reservoirs fill with water, millions of acres of ground that would otherwise be barren are brought to life through irrigation.
Millions of people are served with water that would not be available without dams that form water reservoirs that serve metropolitan areas around the world.
And we are learning to use our dams in more environmentally friendly ways than in the past. The
Hydropower Reform Coalition
is a grass roots conservation group concerned with negative environmental impacts of large hydropower dams as many of them exist today.
No, the Hydropower Reform Coalition doesn’t suggest we destroy all of the dams; though they have secured the removal of some. They believe strongly that dams must be operated with regard for the well being of the river habitat. They work through government regulations and license renewal procedures to secure implementation of better conservation practices by the operators of all dams.
Hydropower Research Foundation
is a hydropower advocacy group. The focus of the organization is the need to develop more hydropower but they also advocate environmentally sound development of hydropower resources.
Are hydropower dams cost effective? It depends.
Some projects could not exist without government involvement. Bigger, longer dams are less likely to make economic sense if we look only at the cost to generate electricity. But many, including those built by governments of the world, pay for themselves over time.
According to the WCD, hydropower dams can be profitable in a pure economic sense. WCD information shows that the Grand Coulee Dam in the U.S. state of Washington has generated about $15 Billion in revenues during its years of operation, with actual operating costs of $5.7 Billion. This dam is a good example of a multiple use project that generates electricity and provides irrigation water.
The Tucurui Dam in Brazil reflects electrical generating costs in the range of $.05 per kilowatt hour, which makes it competitive with fossil fuel generation.
And Bagnell Dam located in the U.S. state of Missouri, is a privately built and privately owned hydro-power dam that has been profitably generating electricity for Missouri customers since 1931.
Dams can also provide water reservoirs, flood control, water for irrigation, and recreation. These added uses encourage dam building and add to the cost effectiveness.
People are drawn to water, so dams are often close to the population centers they serve. Over 45,000 dams have been built and more are being developed.
Although the power available from hydro-power dams is limited, it is a vital energy resource. The WCD states states that, “Hydropower provides 19% of world’s total electricity supply with 24 countries depending on it for more than 90% of their supply.”
World Energy Council Hydropower Data
shows that hydropower is presently generating about 3,000 TWh (Terra-watt hours annually). And, if we include both high head (hydropower dams) and low head (run-of-the-river micro plants) systems using current technologies, we can probably economically generate almost 15,000 TWh annually just from river hydropower.
The total estimated hydropower generating capability of world river resources is about 40,000 TWh annually. But that includes such economically unsound notions as, say, stretching a waterwheel across the Mississippi River to get, maybe, a megawatt of generation capacity that might cost fifty times the amount you now pay for electricity.
Happily, there is no need to go broke building mile wide waterwheels. We have enough economically usable river water resources to generate virtually 100% of current global electrical demand. And we have the technology and know how to do it in far more environmentally sound ways than in the past.
To some, dams and lakes are things of beauty, to others, an environmental nightmare. But like them or not, dams are, and will continue to be important tools of civilization.
As you will see on the Pros and Cons of Run of the River Hydro page, there are ways to harvest power from the rivers of the world without flooding millions of acres. And rivers are only part of the incredible hydropower resources available to us.
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