Oceanlinx has started few years ago a renewable energy project based on wave energy. They first deployed their wave energy conversion unit in 2005 but this had undergone planned refurbishment and modifications this year. Work has been finalized and the unit was re-deployed at Port Kembla in Australia.
The unit is an Oscillating Water Column (OWC) which has a chamber opened underneath the waterline. When the waves rise the water level, the chamber fills with water forming pressure inside. The pressured air is driven past a turbine which is put in the narrowest point of the chamber. As the waves rise and fall the energy is harvested in both directions when the air is compressed in the chamber and when it is sucked back into the chamber. The turbine coverts the air movement into mechanical energy which drives an electric generator.
The most important part of the assembly is the turbine which is quite a special one. Traditional turbines are designed to work for gas or liquid flowing in one direction and at constant speed. However this turbine can work in both directions and at different velocity using a variable pitch blades. The variable pitch blades have slower rotational speed and higher torque improving in this way the efficiency and reliability of the turbine. As well this improvement reduces maintenance. To identify the height, duration and shape of each wave the turbine uses a sensor system with a pressure transducer. The transducer measures the pressure exerted on the ocean floor by each wave as it approaches the capture chamber. This prevents the system from activating at small-scale noise. The signal sent by the transducer is converted by a Programmable Logic Controller which adjusts the blade angle and turbine speed in real time.
The generator has a 450kW induction motor with a variable speed and torque to maximize the power transfer. The Oceanlinx power unit can generate 100kW to 1,5MW, mostly depending on waves height.
The unit can work as well in a farm like system contributing in this way considerably in reducing the impact of the waves to the shores. Time will show if this system will be implemented world wide but until now there are only 6 units running in the world.