Tidal Power Offers Clean and Renewable Energy
The Power of Water Provides a Reliable Alternative Energy Source
Sep 28, 2009
In the race to find alternative energy sources, history can be a valuable resource. Tide mills have been used to harness the energy of water of the western coast of Europe since the 8th century. Tidal power is a consistent and reliable source of energy and does not create greenhouse gases. Today, there are several different types of tidal power generators and more are being developed. The key factors that determine the best generators are the energy produced, cost of installation and maintenance and environmental impact. Other important considerations involve the geography of the installation site and tide strength.
Tidal Barrages
Tidal barrages are placed in tidal bays or estuaries. Similar to dams, tidal barrages collect and trap incoming tide water. Once the water has reached an optimal volume, the water is forced back out through turbines which generate electricity. Tidal barrages have been in use since the 1960s when France installed one at the mouth of the La Rance river estuary. This is the largest tidal barrage in use today. However, there are several smaller barrages in Russia and Nova Scotia.
Tidal barrages are very costly and time-consuming to install but generate significant energy. As barrages are very similar to dams, the size of the structure depends on the size of the tidal bay or estuary. They may also negatively impact the ecology of the site by building up sediment and blocking sea life migration.
Tidal Fences
Built between two landmasses, tidal fences look like giant turnstiles that rotate as tide water pushes past them and generates electricity. They are generally installed in areas where current speeds reach five to eight knots. In currents this strong, tidal fences can generate energy equivalent to wind turbines. Tidal fences may also negatively impact migrating species of sea life, but far less so than tidal barrages.
Tidal Turbines
Like wind turbines, tidal turbines are often free standing. They are the easiest tidal power generators to install and cause the least impact to sea life. They are usually placed seventy to one hundred feet deep in currents that run at four to five knots. Many models are being developed to determine which tidal turbines are the best at generating energy. Some proposed models include attached wind turbines above water in an attempt to generate consistent energy levels between tide intervals.
Further Considerations for Tidal Power Generators
Tidal power generators are limited to collecting energy twice a day at 12.5 hour intervals. Although the amount of energy collected is significant, tides occur at off hours of high energy consumption. All forms of tidal energy generators must be constructed to withstand the force of the tides and environmental stresses. The repairs can be costly and dangerous in the strong tidal currents. However, some models of tidal turbines can be lifted out of the water making repairs much easier and safer. Although initial installation costs are quite high, operating costs for tidal generators is considered low.
References:
 |
 |
