Wave Energy
There is energy present in waves. This is an indirect way to capture the sun's energy.
The wide variety of offshore wave energy conversion devices
capture the kinetic energy produced by the bobbing or pitching motion of the
ocean via floating
platforms. The potential energy production is significant, the average wave off
the Northwest coast of the US carries about 25 kilowatts of energy per meter of
wave crest. At 50 percent efficiency, a 50-meter-wide device would produce about
625 kilowatts of electricity.
The economics of the system are currently being assessed. One of the main problems with wave energy is that any system that would utilize this energy would have to be exposed to the force of storms. To overcome this there would have to be extensive engineering - cost - to be prepared for this.
Currently a wave energy device provides power to the UK grid. A wave energy converter has been successfully installed at the new European Marine Energy Center (EMEC), and has been providing power to the U.K. power grid since the evening of August 15th 2004. The 750-kilowatt device is a full-scale prototype consisting of a series of floating cylinders, each about 11.5 feet in diameter, stretching out over a length of about 130 yards. The device is moored perpendicular to oncoming waves, and three hinges along its length allow the segments to move up and down as waves pass. As each hinge pivots up and down, it pumps high-pressure oil, which is used to drive a generator to produce power.
See:
See the Ocean Power Delivery, Inc., (OPD) press
release
description of the Pelamis
The Pelamis is the first device installed at the EMEC, located near Stromness on the northern Scotland island of Orkney. The new facility officially opened on August 8th, and includes four test berths for wave energy devices, located about a mile and a quarter from shore. The EMEC was constructed at a cost of about $9 million (5 million pounds), and plans are already underway to expand the facility to test tidal energy technologies. See the announcement from the Scottish Executive, as well as the EMEC Web site.
Energetech America LLC announced in September 2004 that it plans to build the first wave energy project in the United States. Located more than a mile off the coast of Rhode Island, the 500-kilowatt pilot project will cost about $3.5 million and will use an existing undersea transmission cable to deliver the power to the New England electrical grid. Called "GreenWave Rhode Island," the project is expected to begin operating in 2006 and to operate for a three-year trial. The Energetech system uses "oscillating water column" technology, in which the up-and-down movement of waves in an enclosed chamber compresses air and forces the air through a turbine to generate power. The structure will measure about 100 feet by 120 feet and will rise 40 feet above the water. Its four legs will rest on the ocean floor, and mooring cables will hold it in place. Energetech plans to begin the permitting process later this year. Energetech's parent company is currently building a similar device for installation at Port Kembla, Australia, later this year. See the model above.