Oceanlinx, an Australian wave energy company, announced plans for a $20 million project to install three floating wave energy converters (WECs), i.e. wave-powered turbine platforms, to supply up to 2.7MW of electricity to the island of Maui, Hawaii. The company has signed a Memorandum of Understanding with Renewable Hawaii, Inc. (RHI), for potential passive investment in a project . RHI is owned by the Hawaiian Electric Company, Inc.The project could be operational by the end of 2009.
Oceanlinx’s unit combines the established science of the Oscillating Water Column (OWC) with its own patented turbine technology, and has successfully completed a full scale trial at its pilot unit at Port Kembla, Australia.
Each WEC is about 65 by 100 feet and 15-25 feet high and will not likely affect views from land.An OWC, is a chamber which is open underneath the waterline and allows the water inside the OWC to rise and fall, compressing and displacing the air inside, driving it past a turbine which is housed at the narrowest point in the chamber, located above the waterline.
Since the OWC chamber narrows, the air is accelerated to its highest velocity as it passes the turbine allowing for maximal extraction of the energy. The oscillatory wave motion causes a similar oscillatory airflow through the chamber, and the turbine converts energy on both the up and down stroke.
The unique characteristic of this turbine is its blade pitch control system which enables it to rotate in the same direction irrespective of the direction of the air flow. This turbine, converts the energy in the airflow into mechanical energy which drives an electrical generator. The Oceanlinx turbine uses variable pitch blades which, with the slower rotational speed and higher torque of the turbine, improves efficiency and reliability and reduces the need for maintenance.
The turbine uses a sensor system with a pressure transducer which measures the pressure exerted on the ocean floor by each wave as it approaches the capture chamber, or as it enters the chamber. The transducer sends a voltage signal proportional to the pressure which identifies the height, duration and shape of each wave to a Programmable Logic Controller (PLC) which adjusts various parameters, such as the blade angle and turbine speed, in real time.
An underwater cable will run from the WEC array along the sea-bed to feed a substation on the Maui Electric Company grid.
Oceanlinx claims the advantage of its system are that all the technical equipment operates above the water, thereby improving reliability and providing easy access for maintenance and repair and that it has only one principle moving part, the turbine, which is also located above water. (Isn’t the generator a principle moving part?) – tfd