[转载]Tidal Energy

April 11, 2014

Tidal energy, also referred to as tidal power, is a renewable source of energy generated by harnessing the kinetic energy of ocean currents and tides. Even though it is still in its infancy stage, it does show signs of a bright future. It has a capacity of producing 64,000 MWe* (Megawatt electrical) power and is much more reliable than solar and wind energy. Owing to this, the proponents of tidal power are of the firm belief that it has the capacity to become a major source of power in the future.

Mankind has been exploiting the kinetic energy of the oceans since the Middle Ages. Back then, it was harnessed to operate huge mills in Europe and some parts of North America. As technology advanced, things became more refined. Today, tidal energy is harnessed by building a huge dam across the river estuary. The dam features some tunnels built in such a manner that whenever the water goes in during the high tide, or flows out during the low tide for that matter, it flows through these tunnels and rotates the turbines inside them, thus generating electricity.

While the whole process comes across as pretty simple, there are a few complications involved.

Every source of energy has its pros and cons; tidal energy is no exception. The fact that it is a non-polluting source of energy, is by far its biggest advantage. Today, when serious questions are being raised about the pollutive nature of fossil fuels, tidal power comes as the best source of energy, as it neither generates waste, nor harmful emissions.

More importantly, it is a source of renewable energy, as the Moon's gravity will continue to cause tides on the planet for centuries to come. This sustainability again gives it an edge over fossil fuels which are on the brink of exhaustion. When compared with other alternative energy sources, like the solar and wind energy, tidal energy is much more reliable, as tides are predictable.

Other than this, the barrage (i.e. the dam) built to harness the kinetic energy of water also doubles up as a protective covering for the coastline in times of rough weather. In other words, it will provide a storm surge barrier. Though the high cost incurred as initial investment is bound to raise some eyebrows, this is expected to change as technology continues to advance and the cost goes down.

Everything doesn't work in its favor though. Some attributes of tidal power generation need to be subjected to a thorough inspection before giving it a go.

The development of tidal power has specific geographical requirements, which put it at a disadvantage by limiting its scope in several regions of the world. More importantly, the locations that are ideal for its development are often remote, which, in turn, adds to the initial investment as well as overall expenditure.

On the economic front, the technology is quite expensive, and is still believed to be in its infancy stage. It is not wise to invest in it purely on the basis of some assumptions, especially when the commercial value is yet to be proved.

Building a dam on the river estuary is a major environmental concern, as it is bound to affect the biodiversity of this region. First of all, the marine life will be exposed to the rotating turbines. If the water is blocked at the estuary, it will affect the salinity levels of the tidal basin. The construction of a dam will change the tidal level of the surrounding area.

While the construction of turbines in the water will directly affect the marine species thriving in it, the change in salinity level and tidal level will affect them indirectly by resulting in loss of habitat for them. Environmentalists are totally against the development of power at the cost marine life and environment.

When asked about the environmental impact of tidal power stations, its proponents are quick to retort that these impacts will be local - not global as in the case of fossil fuels.

What we need to understand, is that the future of energy can't just rely on one source alone. Going by the ongoing trends, our energy requirements are bound to increase manifold in the near future. In such circumstances, it is wise to invest in a couple of efficient and clean energy sources, instead of trying to find a single, perfect one.