Hydroelectricity is electricity generated by hydropower, i.e., the production of power through use of the gravitational force of falling or flowing water. It is the most widely used form of renewable energy. Once a hydroelectric complex is constructed, the project produces no direct waste, and has a considerably different output level of the greenhouse gas carbon dioxide (CO2) than fossil fuel powered energy plants. Worldwide, hydroelectricity supplied an estimated 715,000 MWe in 2005. This was approximately 19% of the world’s electricity, and accounted for over 63% of electricity from renewable sources.
Hydroelectric Power
By Michael Ashcroft
Hydroelectric power, or “hydroelectricity”, is the extraction of energy from moving water.
Where Does Hydroelectric Power Come From?
The sun evaporates water off oceans which then falls as rain and returns to the oceans as rivers. The story is continued by the Earth’s gravity, which pulls the water towards the sea level. What we do is use falling or moving water to power a turbine which generates electricity.
Photo: ga.water.usgs.gov
Types of Hydroelectric Power
There are only really two ways of implementing this: on a large scale, and on a small scale. The basic principles are the same, essentially, only the size of the turbines changes. The most well known method is large scale hydro, which tends to involve damming a river, creating an artificial lake and allowing water to pass through the dam in a controlled way.
The most famous example of this kind of dam is probably the Hoover Dam, on the border between Nevada and Arizona, in the USA. In modern terms, it is actually a lightweight in terms of energy production from hydroelectricity!
Small scale hydroelectric power is really much less impressive, as it is far less obvious. Small scale hydro is used to power small communities who are lucky enough to have flowing water nearby – damming is not really necessary. All you need to do is place a turbine into a river and plug it in, really, which makes it attractive to those wanting to do it themselves. Unlike solar and wind power, however, most people do not have easy access to a river or stream!
Environmental Concerns
The environmental impacts of large scale hydroelectricity require some discussion. In terms of greenhouse gas emissions, the technology is wonderful, as all the energy comes from moving water and not from any form of combustion. As with most things, such gases are emitting in the construction phase, however.
The problems arise when you consider the impact on the local region directly. You suddenly get a large lake formed behind the dam that did not exist before, and the river on the other side of the dam reduces in volume. This has a rather large impact on local wildlife and ecosystems. Unlike wind and solar technologies which tend to have only a minimal impact on their environment, large scale hydro can seriously affect its environment.
There are also only so many rivers that can be dammed, and we certainly don’t want to dam every single river available due to the Environmental impacts. There is also a rather entertaining website which shows the impacts of a well run and a poorly run dam, which you might like to investigate.
Michael Ashcroft is a Physics student at Imperial College London, with a passion for Environmental and Energy issues. In fact, he hopes to make this his career. He’s also a keen musician and photographer, and writes articles on Environmental topics for his website. For more articles, please visit http://www.howtopowertheworld.com
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