Reservoirs and dams: A good idea for hydroelectricity?

Hydroelectric power generation is labelled as one of the most reliable power sources, both on sustainability and eco-friendliness levels.
In 2007, Brazilian scientists conducted studies on human-made reservoirs and dams, and the results were totally unexpected.
More recently as well, scientists at the Washington State University reached similar results concerning gas emissions from dams and reservoirs: these structures cause the release of important quantities of methane.
Discussion about this issue will be divided into three parts: firstly the conclusions of the researches, secondly the impacts of reservoirs and dams on our environment and thirdly the main possible solutions to solve this issue.



Firstly, Brazilian researchers found in 2007 that methane emitted from water reservoirs is responsible for about 4% of human-caused climate change. Other researchers working at the Washington State University recently concluded that reservoirs release one gigaton of greenhouse gases (GHG) each year, which amounts to Canada’s total emissions. Yet reservoirs’ GHG emissions are estimated to account for 1.3% of our total carbon footprint, which is considerable. GHG emissions from reservoirs depend on its depth, capacity, and the temperature of the air surrounding it, as tropical climate for example raises GHG emissions of reservoirs located in such regions.


Secondly, reservoirs help the development of microorganisms. They absorb CO2 and release methane gas, which has 84 times the global warming capacity of CO2. Moreover, when the reservoir is first filled, already rotting organic matters as plants and soils liberate methane, while during the lifetime of the reservoir, carbon-rich plankton and plants, detritus and other organisms are as well emitting gas.
Therefore, reservoirs highly contribute to the global warming and earth’s pollution, while their first purpose is to be one of the main green, non-polluting power generation sources.


Thirdly, despreservoirite the fact that policies commonly integrated hydroelectric power using reservoirs and dams technologies, and considered it as reliable, renewable and green, solutions may be experienced. On one side, new technologies may help to capture the methane released and thus reuse it to generate electricity. Consequently, less dams will be needed and the methane-caused pollution will be restrained. On another side, an important role is played by International Rivers (an international organization that works for the protection of rivers and the communities depending on it)  in lobbying, awareness campaigns and education policy. Decision-makers and every other responsible persons should be aware of their actions and their consequences. For example, the Executive Board of Kyoto’s Protocol Clean Development Mechanism was convinced (mostly because of the action of International Rivers) that hydro projects with large reservoirs could not apply anymore for carbon credits on the carbon market, which is a step forward to limit the damage. The board is now aware that projects using dams and reservoirs may pollute more than they contribute to avoid carbon dioxide emissions.

In conclusion, hydroelectric projects using dams and reservoirs are highly polluting: the development of microorganisms in the reservoirs causes methane to be released in the atmosphere and hence contributes to the global warming. Nevertheless, solutions do exist: catching and storing the emitted methane for electricity generation, awareness campaigns, environmental impact studies, lobbying for a more responsible environmental policy, etc.
In the energy sector, no miracle is possible for a healthy and respectful transition. Things should be analysed meticulously, pragmatically and harmoniously in order to reach a viable future.


picture :
picture :
WSU News, Washington Post



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