Hydropower is easily one of the oldest forms of green energy, probably even predating the term. It rivals wind power in how ancient it is, with the Greeks being known to grind flour with hydropower as far back as 2,000 years ago.[1] Its age makes modern fossil fuel use seem like a fad.
How Does Hydropower Work?
The basic approach to hydropower hasn’t changed in its history since its inception. Just like when the Greeks were using it, modern hydropower plants rely on the fact that water flows downhill. The key technology that all hydropower relies on is the water wheel, which is simply a device that spins when water hits it. Older designs generally relied on something that looked like a paddle boat wheel to spin the water. [2] Modern systems are significantly more advanced.
Modern approaches to hydropower usually involve the damming of a river to increase water pressure. The water is then let out through a small tube that leads to the water wheel, generally a fairly small, compact device that forces the water to push it out of the way if it wants to continue its downward motion. Because of the high pressure and steep angle, hydropower plants can spin their water wheel, which in turn spins the generator at incredible speeds. [3]
The Pros of Hydropower
Hydropower is one of the greenest of green technologies. After it is built, very little needs to be done in order to keep the plant in operation. And hydropower plants have some of the longest lives among power plants, with some expected to last half a century with minimal maintenance. In fact, according to the government, the combined maintenance cost and operation cost of a hydroelectric plant is only slightly higher than that of a fossil fuel plant, without the need for any fuel.
Hydropower plants are often also built where a dam was already going to be built, meaning that the actual cost of the power plant is extremely low. This is reinforced by government statistics showing that hydroelectric power has one of the lowest original plant price among power plants, even lower than fossil fuel steam. The only thing that beats hydropower plants for initial cost of opening are natural gas plants.
The Cons of Hydropower
Hydroelectric power isn’t without its drawbacks, however, and they help explain why hydropower only accounts for 20% of the world’s energy production.
The most obvious problem with generating electricity from water is fairly obvious: A source of water to generate power is needed. Also necessary is a strong river that can easily be dammed off to increase pressure before building a hydropower plant can even be contemplated.
But the damming process can also be quite destructive. As demonstrated by China’s Three Gorges dam, large hydropower plants flood large areas with water and cut off streams that could be vital to communities of animals and people downstream. [4] Also, many species of fish are migratory, using the major rivers as their conduits, and dams cut them off from their spawning areas. Beyond that, the flooding destroys large swaths of habitat, replacing it instead with a new biome. New species move in, and the old ones either move out or starve. Many biologists protest the creation of new dams, even as other environmental activists laud their construction as a means of saving the planet. [5]
Hydropower is Here to Stay
Regardless of the environmental impact, hydropower is here to stay. They are comparatively inexpensive, require little maintenance, and there will be rivers needing to be dammed will into this century. And at every dam, there is a potential power plant. Even if we stopped building dams today, our current ones will last us well into the next half of the century.
Sources:
1. http://www1.eere.energy.gov/windandhydro/hydro_history.html
2. http://www.fallsmill.com/
3. http://hydropower.inel.gov/hydrofacts/plant_costs.shtml
4. http://www.guardian.co.uk/environment/2010/jan/22/wave-tidal-hydropower-water
5. http://www.internationalrivers.org/node/1545
