Ecology And Environment

An Overview of Green Energy Possibilities from the Ocean



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Since the mid-1990s, ocean power, an energy source with both thermal and mechanical energy capabilities, was turned to with renewed anticipation. The U.S. looked to sea waters in hope of fresh and abundant electricity-producing sources. Other countries, Japan in particular, are already now harnessing this massive force. Researchers say water power holds greater potential over wind power and could soon rise to status as the world's newest and fastest growing alternative energy source.

Ocean energy is split into three main categories of energy production:

1. Tidal Energy:

Changing water depths here are the main sources of energy. Caused by the gravitational pull of moon and sun, tides are used for their high power potential.
This process uses several forms of gate or barrage to run through a certain section of water, however, it has to be at a high-low tide difference of about 16 feet. The limited measurement allows for an estimated 40 sites on Earth to having access to this energy.
The three methods for collecting tidal energy include using: a barrage or dam, a tidal fence, or a tidal turbine.

The barrage is typically a larger structure set as a wall across a watery area; turbines stud the dam. When an exceptional degree of water level is measured, the turbines allow water through, activating a linked-up generator to start producing electricity.
Tidal fences are reminiscent of the barrage but are built with rotating sections along their structures. The sections spin due to shifting tidal currents creating energy. Because of seawater's density, this method produces much greater energy levels than wind power.
Tidal turbines look much like wind turbines and function almost in the same ways. Arrayed in rows, the turbines, like the fences, catch their energy in the form of coastal currents. Although more expensive, they have more energy-producing potential and are sturdier and more size-effective than the wind turbines.

Tidal energy structures are known to cause underwater build-up and are a possible hazard to sea-life. Turbines, with their compact size and slower spinning blades, seem to be safest and most efficient of the tidal energy methods.

2. Wave Energy:

Waves are looked upon as one of most likely sources of future energy to date. There are now more wave-energy programs than other oceanic energy experimentation. The power of sea water is tremendous. Waves around the U.S. coast carry a possible 2-3 million megawatts and are capable of providing power to entire local communities.

Wave energy can be brought in from both offshore and onshore systems.
Offshore systems are located in deep waters, using the rise and fall of sea waters for a continuous energy source. The system rides the varying currents, sending signals to either a pump or turbine to begin an energy-creating process.
Onshore systems are found along the shore, catching the energy of coming waves.
This system is usually seen as a box design. It can be either entirely visible or partly submerged to non-visible. The design is made to trap waves by way of a tapered channel and then to use their swinging momentum in order to power a series of connected electricity-making turbines.

Wave systems are both cheaper and easier to set up and maintain than other ocean energy systems. They are, however, still behind traditional energy sources and the competition isn't letting down. Some experts do believe that the wave energy method may soon find a future market and replace current systems.

3. Ocean Thermal Energy Conversion (OTEC):

An older method first proposed in 1881, the OCET system uses heat difference for energy conversion. With the sun heating from the top, water at the ocean's floor can be 40 degrees lower than that of the surface. Varying depths must provide a difference of at least 25 degrees Celsius for this method to be effective, limiting the working points to tropical areas.

The newer, hybrid OCET system combines two previous methods, the closed and open cycles into one. Warm sea water spills into a submerged chamber where it is then evaporated into steam. The steam hits a low-boiling-point fluid which is vaporized on contact, driving a turbine to produce electricity.

As a byproduct, the OCET system produces rich water full of nutrients for thriving sea life. This, plus another feature allowing the system conversion of seawater to freshwater, makes the OCET method both safe and effective. The costliness for keeping a continuous fuel-powered extraction system, however, highlights this method as most expensive and least likely, while other energy sources still exist, to go into mass use and production.



Though marine power is still in its developmental stages, many are already adapting to its many potentials. With fossil fuels running scarce, oceans may one day become much more than just favored vacation spots but a key to our world's energy.

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