HOW CAN THE OCEANS SERVE AS A GREAT POTENTIAL POWER SOURCE FOR THE EARTH?

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The fall of water has been a source of energy for humans on earth for more than a thousand years. Thanks to our orbiting moon, twice a day the earth's oceans create powerful water currents and a rise and fall of tides that have huge energy production potential. This change in water level can be used near coast lines to generate electric power that can be channeled inland. Humans experimented with tidal dams as early as the 1930s but other systems that rely of tidal water movement are currently being studied.

Although renewable energy encompasses a wide variety of alternatives, harvesting wave energy may serve as a viable alternative source of electric power for only coastal states such as Florida. Electric conversion of wave energy can be accomplished through the use of mechanical devices that either directly or indirectly drive a generator. In turn, this power is transported to shore via submerged cables and then connected to a power grid. This supply, coupled with today's technological advancements, may provide an endless source of energy for a coastal state such as Florida.

Because Florida has 1,350 miles of coastline, harvesting the energy of the sea is a practical way for the state to expand the use of renewable energy. In Florida's 2003 Assessment of Renewable Electric Generating Technologies, limited consideration was given to the power that could be harvested from the ocean waves. In view of the fact that wave energy is one of the largest available renewable sources on Earth, it is imperative that future assessments of Florida's renewable sources include a more extensive evaluation of its potential.

Through technological advancements, many companies convert kinetic wave energy into mechanical energy that is used to drive a generator. This energy is then sent to the power grid via submerged transmission lines. Today, there are a variety of prototypes in operation across the world including the "Power Buoy," the "Monitor," and the "Pelamis" sea snake. Ocean Power Technologies (OPT) utilizes independent ocean buoys to generate electricity. Studies conducted by OPT indicate that installation of Power Buoys in a 100 square mile farm off the coast of California is likely to produce enough electricity for the entire state of California. This translates into providing power to a population of 40 to 50 million people.

The largest system in operation today is Ocean Power Delivery Limited's (OPD) innovation. In May 2005, Portugal began construction of the world's first commercial wave farm off the north coast of Portugal, near Povoa de Varzim. The OPD wave conversion system called "Pelamis" or "sea snake" is a 120-meter segmented cylinder that utilizes wave motion to produce electricity. The initial phase of the wave farm includes installation of three Pelamis devices, with a capacity of 2.25 MW. This stage of the project "is expected to meet the average electric demand of more than 1,500 Portuguese households." If this initial stage performs satisfactorily, thirty more Pelamis machines are intended to be ordered for the farm to produce an additional capacity of twenty MW. The project cost per MW is only about $472,000, and the total cost of the project is approximately $10.5 million.

Although many may anticipate that the initial investment cost for many wave energy systems is more expensive than that of fossil fuel plants, wave energy systems have low operating costs once built and are competitive with other technologies when used as a primary source of power. After all, they have no fuel costs. Another advantage of this technology is its high energy density, making it well-suited for large-scale developments capable of generating multiple gigawatts of power.

Waves are more powerful and predictable than wind, and thus are potentially more useful in coastal states. To put this in perspective, "[s]ea water is 832 times as dense as air, providing a 5 knot ocean current with more kinetic energy than a 350 km/h wind." Additionally, in areas where researchers conducted detailed examinations, the discovery of additional suitable sites suggests that the available kinetic energy in waves may be considerably larger.

Humans experimented with tidal dams as early as the 1930s but other systems that rely of tidal water movement are currently being studied. Such systems are believed to be some of the most environmentally friendly methods for generating electricity. Tidal movements are natural; using this movement to produce electricity would result in no greenhouse gas emissions, and a dimensional cross section of air must be traveling at more than 125 miles per hour to have the same power producing capacity to that of an equal cross section of water moving at just 5 miles per hour. Clearly, the ocean deserves to be researched as a viable and cost-effective method of power for those states able to harness it.

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