Energy and the Environment-A Coastal Perspective

OTEC facilities may be placed in three different locations, either on shore, on a continental shelf, or floating in open water.  Each site has its own benefits and setbacks.

On-land or near-shore OTEC plants have a number of advantages.  First, with its location so near land, there is far less concern regarding mooring, cables, and lengthy pipes.  Rather than having to maintain the plant far out in the water, the near location makes it far easier to control and maintain.  Additionally, these plants may be placed in a location that is sheltered from storms and larger waves that are found farther out in the ocean.  Additionally, the near-shore plant is able to contribute to the industries involved with mariculture and those that need desalinated water, as the plant supports mariculture as well as desalinates the water it cycles through.  However, there are some negative aspects to the nearby location.  These plants are often subject to the turbulent waves which are sometimes found in the surf area.  These waves may cause extreme stress and damage to the pipes and rest of the plant.  Additionally, so as not to disrupt the quality of the water, cold, deep water that has been cycled through the plant must be piped deeper out in the ocean before it is released.  With that being that case, an on-land or near-shore plant would require a long discharge pipe in order to get the water far enough out.

OTEC plants might also be placed on a continental shelf.  This allows the plant to avoid the turbulence that may be found in the surf, however, this provides new difficulties.  Due to the difficulty in anchoring and stabilizing the plant, this is a more expensive method.  The plant might also require long cables in order to transmit the energy produce to shore.

The third site for a plant is floating out in the water offshore.  This, too, has its own benefits and drawbacks.  With wide-open location, there is potential to produce much larger plants, some perhaps large enough to support wind turbines on top.  While this potential is great, this also makes the plant far more difficult to stabilize and maintain.  Additionally, these floating plants are vulnerable to the strong wave power and turbulent conditions of the open ocean.  This may cause damage to the pipes and the rest of the plant.  Additionally, long cables would be necessary in order to transmit the energy produced.

Left: OTEC pipes Right: Floating OTEC plant, India 2000

Each location has pros and cons and so researchers are continuing to explore each method to determine the most efficient locations for each new plant.

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