Hinged Contour Converters

Both the AquaBuOY and the Seadog mentioned are point absorbers because they interact with only a small ocean area. To generate large amounts of energy, a multitude of these devices must be deployed, each with its own piston and power takeoff equipment. The solution developed by Pel amis Wave Power, formerly (prior to 2007) known as Ocean Power Delivery, Ltd., although also using a system of buoys, is capable of interacting with a much larger ocean area.

The 750-kW prototype called "Pelamis" (see Figure 16.3), installed at the European Marine Energy Centre in Orkney, ^ consisted of four tubular-steel floats measuring 4.63 m in diameter attached to one another by hinges. The length was 150 m.

Figure 16.3 The Pelamis hinged contour converter.

1 The Orkney Islands form an archipelago some 50 km north of the northernmost, tip of Scotland.

Wave motion

Wave motion

Figure 16.3 The Pelamis hinged contour converter.

The force the waves exert in moving each segment relative to its neighbors is captured by hydraulic rams that press a biodegradable fluid into accumulators, which, in turn, power a number of 125-kW generators.

The system was moored by a three-point configuration that allowed Pelamis to orient itself normal to the incoming wave front. The natural resonance of the system is automatically altered to match the frequency of the waves. However, when exposed to storm conditions, the system is detuned to minimize the stress on the mooring. Simulations and actual tests show that Pelamis appears to exhibit excellent storm survivability.

In 2008, three Pelamis P1 machines were installed and were in the process of being commissioned at the Agucadoura ocean energy farm, 5 km offshore in northern Portugal.^ These three units will deliver 2.25-MW peak (3 x 750) with an estimated plant factor of between 25% and 49%. The plant factor depends on the average yearly ocean behavior and will probably be narrowed down, as electricity production data are accumulated.

A slightly larger Pelamis-equipped wave farm is planned for the Orkney site where the original prototype was tested. It will consist of four units (3MW, peak).

The P1 production machine differs slightly from the prototype. It is 140-m long and 3.5 m in diameter.

Solar Stirling Engine Basics Explained

Solar Stirling Engine Basics Explained

The solar Stirling engine is progressively becoming a viable alternative to solar panels for its higher efficiency. Stirling engines might be the best way to harvest the power provided by the sun. This is an easy-to-understand explanation of how Stirling engines work, the different types, and why they are more efficient than steam engines.

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