Technology in Wave Energy
Wave energy is a great renewable energy source. Several technologies are being developed that convert kinetic wave energy into electricity; however, the cost of construction is the biggest obstacle to implementation. Ocean wave technologies are cool renewable energy tools, but until oil prices rise significantly, the feasibility of widespread use is unlikely.
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Technology
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Waves are created through a complex interaction between Earth's gravity, the moon, the wind and ocean water temperatures. Only certain types of waves, those created with 3 to 8 knots of wind or with at least 16 feet difference between high and low tides, are suitable for energy production. Three different types of technologies have been developed that harness energy from these types of waves.
Barrier Technology
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A barrage is a barrier. When used in wave energy technology, it is composed of gates and turbines linked together to form a dam. The wave level on either side of the dam must exceed 16 feet, the difference between high and low tides. At which time, the gates open to allow sufficient flow of water to turn the turbines, generating electricity. This is transmitted to the grid via a tethered underwater cable. The dam is anchored to the sea bed with a cable. A variant of this technology uses encased hydraulic rams that seesaw back and forth along the waves to power a generator. The Pelamis Wave Energy Converter is an example of this technology.
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Fence Technology
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A channel produces a steady flow of clean and untapped energy. Tidal fences are basically rows of turnstiles that move water instead of people to power a turbine. Tidal fences are suitable for use across channels, between islands, or across straits between an island and the mainland. The flow of seawater currents spins the pinwheel-shaped devices, turning the turbine linked to a generator. Because seawater is denser than air, 5 to 8 knots will effectively run the turbines, much less in comparison to wind speeds necessary for on or offshore wind turbines. Blue Energy is a Canadian company that manufactures tidal fences.
Oscillating Turbine Technology
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Tidal turbines simulate wind turbine technology, but transform it for underwater use; the movement of water over the turbines generates power. An oscillating water column is an example of a tidal turbine. Many devices are necessary for effective power generation. While offshore wind turbines can be placed miles away from shore, tidal turbines need to be close to shore at 65 to 100 feet deep to get water speeds of 3 to 5 knots.
Costs and Impacts
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Wave energy technology is only suitable in areas with sufficient wave speed and height, a limited number of which are available around the globe. Construction costs are generally prohibitive, except for places like Hawaii where the high cost of transporting fossil fuels makes finding other local energy sources like the ocean appealing and imperative. Environmental impacts are unknown, but wave energy technology will likely affect marine life migration patterns by preventing free movement, and habitat may be impacted as silt accumulated through operations is dumped on top of the seabed.
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- Photo Credit majestic waves 6. image by mdb from Fotolia.com kayak trip image by Stacey Lynn Payne from Fotolia.com
