By Ira Leiviskä
The Hoover Dam in Nevada, United States
Hydropower is considered to be a green, environmentally friendly source of energy. After all, it is based on moving water, which earth has a vast supply of. Surely it is a better alternative to fossil fuels, which release major greenhouse gas emissions. Or is it?
What is hydropower?
The most common way of utilizing hydropower is through a power plant which is usually situated in a dam that has been built into a river. The plant normally has three parts: the plant where the electricity is generated, the dam which controls the flow of the water, and a reservoir where the water is stored. The water flows through turbines which spin a generator and transform the movement into electricity. Then it can be transported into homes and factories via electric lines.
Hydropower can also be produced with the tidal movements of water, but tidal plants are still few and far between. This way of producing hydroelectricity is nonetheless being studied, and could possibly be a success in coastal areas.
A cheap and clean choice
Hydropower is a good source of electricity in the sense that once the plant has been built, there are very few costs. The river flow is basically free and infinite as long as rain falls and snow melts. Also, the reservoir enables the flow of water through the system to be controlled, so that the power plant can respond to demand more easily. From this point of view, it is better than other so called renewable energy sources, like wind and solar power. Hydropower is also clean in the sense that there are no such greenhouse emissions as when burning fossil fuels, nor radioactive waste like in nuclear plants.
Destroying natural habitats
Although hydropower may sound like a dream solution to the global warming problem, this is not quite true. It has been measured that large reservoirs in tropical areas cause greater carbon and methane emissions than burning coal or natural gas. This is due to the large amount of vegetation which decomposes in anaerobic conditions under the water. This may also happen in colder environments, where the excess nutrients in the water cause algal blooms.
Another environmental detriment of reservoirs is that they harm wildlife by filling their habitat with water. Large reservoirs can even destroy forests and agricultural lands. In addition, dams prevent migrating fish like salmon from swimming upstream to spawn.
So what to think?
There are disadvantages in every form of energy production, so to avoid all the negative effects is nearly impossible. Still, the use of renewable energy sources has far fewer disadvantages than the use of non-renewable alternatives, such as fossil fuels. For example, hydro power doesn’t produce air pollutants, unlike coal and natural gas, which can cause health effects such as breathing problems, neurological damage and cancer. Coal burning emits also sulfur, which produces acid rain and leads to damages in the forests and aquatic ecosystems.
Although, hydropower is already a better solution than non-renewable energy sources, there are still problems that need to be faced. To minimize the environmental effects of hydropower, the industry should favor narrow and deep riverbeds that can store more water with less damage to the surrounding environment. The reservoirs can also be used, for example, in agricultural irrigation, flood control and for recreational purposes in order to make the best out of the situation. In addition, to ensure that the nutrient levels stay optimal and that the anaerobic decomposition is avoided, the reservoir water needs to be aerated regularly. It is also important to assist the upstream migration of fish by providing fish ladders and cannons. To read more about this subject, check Rena’s upcoming blog post about fish cannons.
The future of energy production lies in the development of the sustainable and renewable energy sources, so be conscious and keep on reading this blog to get more information about environmental issues!
Degree Programme in Energy and Environmental Engineering,
Tampere University of Applied Sciences