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Beyond waves: Why oscillating water columns (OWCs) could revolutionize future energy.
As the global demand for renewable energy increases, oscillating water column (OWC) technology is gradually showing its potential as a new type of wave energy conversion device. The device generates energy by using the vibrations of the seawater inside it caused by ocean waves. Since OWC has a relatively small environmental impact compared to other energy systems, more and more companies are developing more efficient OWC models.
The oscillating water column device consists of a semi-submerged chamber or hollow structure with an opening at the bottom connected to the ocean. An air pocket is retained above the chamber. As the waves push, the water column moves up and down like a piston, forcing air into the chamber. Indoor and outdoor flow.
This continuous movement causes the air to flow in a bidirectional high-speed airflow, which is converted into energy through a power conversion system (PTO). It is worth noting that OWC's PTO system can continuously generate electricity during the bidirectional movement of airflow. This feature gives OWC considerable power generation stability.
Design
Basic OWC components
Power Transfer System (PTO)
The PTO system is the second major component of an OWC machine. Its main function is to convert pneumatic energy into the desired energy form (such as sound or electricity). The design of the PTO system is critical to the efficiency of the oscillating water column and must be able to convert both the airflow inside and outside the chamber into energy.
Wells Turbine
The Wells turbine was designed in the late 1970s by Professor Alan Arthur Wells of Queen's University Belfast. It is a bidirectional turbine using a symmetrical airfoil. The turbine is designed not to come into direct contact with the ocean, but its efficiency drops at high air speeds because the high angle of attack of the airfoil increases drag.
Hanna Turbine
The Hanna turbine was invented in 2009 by environmental activist John Clark Hanna as an improvement on the Wells turbine design. The Hanna turbine utilizes two back-to-back asymmetric airfoils. This design not only reduces drag but also increases the lift coefficient, making the turbine less likely to stall and enhancing torque.
History
The earliest applications of oscillating water column technology appeared in sound-generating buoys, which used air pressure generated in a chamber to drive a PTO system to produce sound. In 1885, Scientific American reported on 34 such sounding buoys operating along the coast of the United States.
In 1947, Japanese naval commander Yoshio Masuda designed an OWC navigation buoy that could generate electricity, marking the transition of OWC technology to generate electrical energy.
Large OWC Power Plant Project
LIMPET, Isle of Islay, Scotland
The plant opened in 2001 and has a 2.6-meter diameter Wells turbine capable of generating 500 kW of electricity.
Mutriku, Basque Country
The plant opened in 2011 and is equipped with 16 Wells turbines, capable of generating around 300 kW of electricity under the right conditions.
Ocean Energy Buoy
The project is being developed by OceanEnergy and the full-scale buoy is expected to have an output of approximately 500MW.
MARMOK-A-5
The OWC buoy, developed by Oceantec and IDOM, was tested on the Biscay Sea Energy Platform in the Basque Country.
Environmental impact
The environmental impact of the oscillating water column technology is relatively limited because it has no moving parts in the water, reducing the risk to marine life. However, the noise pollution they may cause is one of the main concerns at present.
Some experts suggest that these negative impacts could be reduced by placing OWC devices farther from the coast, which might also allow the devices to perform better.
The oscillating water column technology seems to have shown that it can become an important solution for future energy, but whether it can really be widely used remains to be proven in the future?
