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Debate: Hydroelectric dams

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Should hydroelectric dams be a part of plans to combat global warming?

Background and context

Dams have existed for thousands of years for various purposes, such as irrigation and flood-control. In the 19th century, they began to be used for hydroelectricity, and by the 20th century, they had become a mainstay of electricity generation. As of 2005, hydroelectric power, mostly from dams, supplied 19% of the world's electricity, and over 63% of renewable energy. Yet, dams have been the subject of significant controversy among environmentalists in recent decades, mainly due to the local environmental costs of dams to river ecosystems.
Largely for this reason, new dam construction has wained, and dams have been de-emphasized as a renewable energy source. With the emergence of the global warming crisis, though, hydroelectric dams, which generate massive quantities of electricity without burning fossil fuels, have received attention once again. The main question and debate is whether governments should include, prioritize, and even subsidize modern hydroelectric dams in 21st-century plans to combat global warming? Multiple questions frame this debate: Can dams help substantially reduce greenhouse gas emissions and combat global warming? Are dams carbon neutral? While hydroelectric generation does not itself release greenhouse gases into the atmosphere, what about the energy used in constructing dams as well as the reservoir created behind a dam (deforestation and decomposition)? Do dams generate enough 0-emission electricity to have a large-scale impact in cutting emissions? Can hydroelectricity grow to help replace coal? Are dams "renewable", or do they have a limited life on rivers? How do dams impact river ecosystems? Are hydroelectric dams economical, or do they require significant subsidization? How do dams compare to other electricity sources on price? Do dams provide needed irrigation waters to farms? Do they supply needed water to surrounding populations? What human rights issues are involved in the construction of dams and the frequent displacement of local peoples? Are dams aesthetic? Do they provide recreational space? Finally, does the political and popular will exist to make hydroelectric dams a major component of plans to combat global warming?

See Wikipedia's article on hydropower for more background.

Contents

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Global warming: Can hydropower help cut emissions, fight global warming?

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Yes

  • Dams cut emissions and fight main crisis: global warming Many environmentalists complain that hydroelectric dams have environmental costs at the local level to river ecosystems. While this is true, it is important to recognize that hydropower is essentially 100% clean when it comes to global warming. This is because it burns no fossil fuels and so emits no greenhouse gases. If we conclude that global warming is the greatest environmental crisis facing mankind, the fact that hydropower helps fight it should weigh much more heavily than the local ecosystem costs.
  • Steps can be taken to limit Methane emissions from dam reservoirs A 2000 World Commission on Dams report concluded: "All large dams and natural lakes in the boreal and tropical regions that have been measured emit greenhouse gases… some values for gross emissions are extremely low, and may be ten times less than the thermal option. Yet in some cases the gross emissions can be considerable, and possibly greater than the thermal alternatives".[1] This indicates that dams can be created that emit "ten times less than the thermal option". The methods used to create these clean dams can and should be followed, can eliminte concerns regarding Methane emissions, and can preserve hydroelectric power as a global warming solution.
  • Hydropower is a clean alternative to coal. Coal is the greatest source of electricity in the world. In places like the United States, it constitutes over 50% of the electric energy supply. It is also one of the greatest emitters of greenhouse gases and, therefore, contributors to global warming. Replacing coal, therefore, is one of the greatest priorities in the fight against global warming. Hydrolectric power, as a primary electricity supplier around the world, can act decisively as a substitute to coal electricity generation. Because hydroelectric emits 0 greenhouse gases, it is a highly valuable substitute for coal, and thus a major tool in the fight against global warming.
  • Hydropower is capable of scaling to fully replace coal. The World Energy Council Hydropower Data shows that hydropower is presently generating about 3,000 TWh (Terrawatt hours, or millions of megawatt hours annually). If we include both high head (hydropower dams) and low head (run-of-the-river micro plants) systems using current technologies, the world can probably economically generate almost 15,000 TWh annually.[2] This means that hydropower could move from its current position of supply roughly 10% of all electricity demand globally to supplying upwards of 50%. Some argue that "we have enough economically usable river water resources to generate virtually 100% of current global electrical demand."[3] This is a very important conclusion, as it means that hydropower is a viable long-term 0-emissions alternative to coal, the biggest culprit in the global warming crisis.
  • Hydropower is more proven/reliable than other renewables Unlike the many uncertainties and risks surrounding modern renewable and green alternatives, there are no uncertainties in regards to the technologies used in hydropower, the price-competitiveness of it, and the electricity return for any given dam project. In the face of the global warming crisis, the reliability of hydroelectricity as a 0-emission alterntive source of energy should be embraced.


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No

  • Dams eliminate forests that absorb CO2 from the atmosphere. Forests and plant life are important carbon sinks, sucking CO2 (a greenhouse gas and contributor to global warming) from the air in the process of photosynthesis. Forests are, therefore, important in the fight against global warming. Killing trees by cutting them down to make room for dams and their infrastructure, by flooding them upstream under a dam's reservoir, or by diminishing downstream nutrient flows all eliminates these important carbon sinks. This only contributes to the greenhouse gas effect and global warming.
  • Constructing dams burns massive quantities of fossil fuels Dams are massive steal and concrete objects constructed in remote areas. The amount of energy required in creating and transporting steal and pouring concrete for dams is unparalleled by any other modern engineering endeavor. Fossil fuel is the primary fuel used to power the equipment and vehicles that perform these tasks. Dam construction, therefore, emits massive quantities of greenhouse gases and contributes mightily to global warming.
  • The world's rivers are covered with dams; room for expansion is limited. Sixty per cent of the length of the world's large river systems are at least moderately or severely fragmented by dams. In this context, there is not much more room for expanding hydroelectric power, particularly if we value keeping a portion of the world's rivers free of dams. This means that dam hydroelectricity cannot expand very much, and so should not be seen as a major part of new energy plans and solutions to global warming.[4]
  • Industrialized countries have tapped most of their hydropower. Industrialized countries have tapped most of their hydroelectric potential. The expansion of it is mainly in un-industrialized countries. This is an important limitation to the future of hydroelectricity.
  • Mass of dam reservoirs has shifted Earth's gravitational field. The amount of water captured in dams has shifted the weight of the earth toward the equator which in turn effects the earth's gravitational field. This has the potential to destabilize the earth generally, and possibly in ways that interact negatively with global warming.
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Renewable: Are dams a renewable resource?

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Yes

  • Dam hydroelectricity is a renewable energy resource. Rivers never stop flowing as they are an integral part of the perpetual water cycle. The sun will always cause water to evaporate and rain down on mountains, continually replenishing the flow of rivers and the supply of hydroelectric energy. This makes dams a fully renewable resource.


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No

  • Dams are not renewable as they clog rivers over time All dams block silt from moving down stream. Silt and other debris build up behind dams, clogging the flow of water more and more each year until a river becomes effectively "clogged" and a dam becomes inoperable. Because dams are unsustainable in this way, they cannot be called "renewable".


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Ecosystems: Are the costs of dams to wildlife and ecosystems worth it?

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Yes

  • Fish ladders allow fish to swim upstream of dams. While many continue to argue that dams inherently prevent the movement of fish upstream to spawn, this is simply not true. Dams can be built with fish ladders, which allow fish to navigate up and around a dam to reproduce. As long as all future dams are built in this way, this argument against dams should be dropped.
  • Dam reservoirs can actually create fish habitats. While dams do diminish the spawning of many fish, the reservoirs created by dams can also create new habitat for fish.
  • Most animals can adapt to the flooding of land near a river. Most animals that live near rivers have to be able to adapt to natural floods and can easily do the same with the slow (not rapid) flooding of the area above a dam in the creation of a reservoir. Most animals are not killed by this process and adapt just fine.
  • Natural floods occur often so a dam-generated flood no big deal. Environmentalists do not cry foul when natural floods occur and destroy plant life and wildlife. Why should they cry foul when it is done by a dam?
  • Dams provide flood control that can protect wildlife and habitats. Dams can open and close to regulate river flows and avoid natural flooding. This protects wildlife and vegetation alike.
  • Many aquatic species have no problem adapting to impounded waters. Aquatic life living in rivers is typically capable of adapting to changing environmental conditions, including the impounding of waters.


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No

  • Dams can destroy marine fisheries Dams disrupt river-borne flows of freshwater and nutrients into oceans, which destroy marine fisheries. Patrick McCully. "Big dams, big trouble". New Internationalists. March 2003 - "Sixty per cent of the length of the world's large river systems are at least moderately or severely fragmented by dams and related withdrawals of water for irrigation...This massive replumbing of the world's rivers is a major reason for the rapid loss of freshwater species. Around a third of freshwater fish species are classified as extinct, endangered or vulnerable. A significant but unknown share of shellfish, amphibians, plants and birds that depend on freshwater habitats are also extinct or at risk."
  • Flooding from dams can disrupt wildlife populations. The upstream flooding from dams and the lasting reservoir permanently displaces wildlife that have previously inhabited the land. A significant portion of this wildlife is not displaced, but actually killed.
  • Big dams can cause damaging earthquakes. This is due to the weight of water in reservoirs, which can induce geological, tectonic activities.
  • Big dams can lead to coastal erosion. This is because the sediments that eventually fill reservoirs would previously have flowed out through estuaries and been washed back by waves to protect the shoreline.
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Economics: What are the economic pros and cons of hydropower?

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Yes

  • Dams are economically viable and often highly profitable. The Grand Coulee Dam in the U.S. state of Washington, for instance, has generated about $15 Billion in revenues during its years of operation, with actual operating costs of $5.7 Billion.[5]
  • Dams last over a hundred years; good return on investment Alan Ervine, professor of water engineering at Glasgow University, said in April 2008, "Hydropower is far cheaper compared to other renewable sources. Each of the large dam schemes will probably last for 100 years. So they have good cost-effectiveness."[6]


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No

  • Dams can flood populated areas and displace people at great cost. The reservoir created by dams often floods populated areas up stream, displacing the former residents of these areas. Displacing a group of people in this way means disrupting their economic productivity and causing their unemployment. This comes at great economic cost. It also comes at great emotional cost to the displaced.
  • Hydroelectric dams require massive initial capital investments. Hydroelectric dams are massive projects that require tens of millions of dollars, and sometimes billions of dollars to construct. This is a very steep initial investment.
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Agriculture: Do dams help or harm agriculture?

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Yes

  • Dams provide flood control that helps protect farms. Natural flooding can be easily mitigated in rivers with dams because the dam can be opened and closed to regulate flow and avoid flooding. This protects agriculture and farms in and around the river.


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No

  • Dams can flood farmland at great economic cost. Dams create reservoirs that often flood farmlands up stream. This ends the economic productivity of this farmland, sometimes at great cost.
  • Dams strip the downstream soil of needed nutrients. Rivers carry nutrients downstream, upon which much river-side plant-life and agriculture depends. Dams block the transport of these nutrients, which can dramatically damage the fertility of downstream soils.


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Water supply: Are dams an important form of storing and supplying water?

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Yes

  • Dams supply water and help counter global water shortages Global warming has the consequence of distorting rain fall globally. It creates greater rainfall in some areas and greater drought and water shortages in others. In areas where global warming is causing water shortages, dam reservoirs provide a good solution by helping store water.


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No

  • There are better ways to store water than dams. Underground water-storage is a superior alternative to storing water in dam reservoirs. The main reason is that storing water above ground risks contamination, evaporation, damage to ecosystems, and flooding.


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Human rights: Are dams consistent with human rights?

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Yes

  • 2 billion people lack electricity; dams are a major solution. Almost 2 billion people, both urban and rural poor, have no access to electricity at all. Dams are seen as a primary component of supplying these people with reliable electricity. Dams are, therefore, a primary component of development and modernization in poor countries. In this context, dams can make major contributions to improving living standards and human rights globally.
  • Human-rights abuses do not inherently accompany dams. While human rights abuses might have accompanied dams in the past, they are not an inherent component of hydropower. Human rights abuses can be effectively eliminated with sound monitoring and regulation.
  • Human displacement does not inherently accompany dams. Dams can be better located to minimize the displacement of human populations.
  • The displacement of humans can be done more sensitively. The displacement of humans can be done with greater sensitivity to the displaced. This can include cash payments to the displaced as well as employment offerings or job retrainings. These are appropriate measures and can sufficiently minimize the impact on the displaced.
  • Dams are not the only projects that displace people. Many major societal projects displace people. Governments frequently and legitimately have the right of eminent domain to seize land for such projects as highways and public water works. Dams should not be alienated in this regard.


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No


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Safety: Are dams safe for humans?

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Yes

  • Modern dams are virtually 100% safe from collapse. It is true that dams have collapsed in the past. But, these dam collapses occurred where modern technologies and regulations were not employed. With these technologies and regulations in place, there is virtually no risk of future dam collapses.
  • China's 1975 dam crises should not be used against modern dams. It was built in the early 1950s by China's early communist regime with virtually no safety regulations in place. It was also the result of the catastrophic Typhoon Nina, events which do not occur around most dams.


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No

  • Dams can burst at great cost to human life. Dams hold a massive amount of water behind them in their reservoirs. In the event of a dam collapsing, this water can be unleashed on a population at great cost to human life. In 1975, two large dams burst in central China that killed as many as 230,000 people.[7]


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Recreation: Do dams create good recreational areas and activities?

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Yes

  • Reservoirs created by hydropower dams act as recreational areas. The large reservoirs created by dams create open bodies of water that are much more suitable for boating, water skying, fishing, and other activities. These recreational activities are good in of themselves, but can also act as an important economic stimulus for communities.


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No

  • The construction of dams destroys previous recreational opportunities. In order to create a large vertical drop for power generation, dams are often build on rivers that have a significant gradient and whitewater rapids. Because of this, many reservoirs flood rivers that previously provided whitewater rafting and kayaking opportunities. Furthermore, fishing is often better in free-flowing rivers and reservoirs.
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Aesthetics: Are dams aesthetic?

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Yes

  • Dams are often viewed as magnificent and beautiful. There is a reason why dams are major tourist attractions. They are a magnificent and awe-inspiring site to see.
  • The "greenness" of renewable hydropower is beautiful. The fact that dams burn no fossil fuels and emit no greenhouse gases is a beautiful thing. With this perspective in mind, dams can be viewed as beautiful.


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No

  • Hydropower ruins beautiful landscapes. Hydropower and their reservoirs destroy natural landscapes and impose man-made creations upon them. This tarnishes the beauty of pristine river ecosystems.
  • Big dams are man-made monstrosities. Big dams are monstrous man-made concrete objects.
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Demolishing dams: Is it a bad idea to demolish dams?

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Yes

  • Demolishing dams does not cause rivers to return to normal. The silt built up behind dams will not simply wash down a river when a dam is demolished. Instead, the silt will distribute itself more slowly along the river, changing and even damaging the riparian zone ecosystem there. The article, "Tales of the Undamned", documents this problem. While this may be seen as a cost of building dams in the first place, it should also be seen to negate the main argument for demolishing dams: that it will somehow improve the environment.


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No

  • Dams are an environmental injustice and should be demolished. Dams have been wrongly constructed on rivers around the world. They damage a river ecosystem and effectively rape the earth, exploiting it for it resources without concern for the environmental destruction. Each day that a dam continues to exist is an additional day in which these injustices are perpetrated. For this reason, dams around the world should be demolished.
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Politics: Is hydropower politically feasible? Public opinion?

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Yes


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No

  • Damming cross-border rivers can cause international disputes. It is common that a river crosses through two different nations. The nation "upstream", if it chooses to dam the river, can degrade the value of it where it crosses through the other nation. This can cause disputes and even conflict.


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Pro/con sources:

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Yes


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No

See also

External links


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