by What are Wave Energy Converters?
Wave onverters are mechanical devices that capture energy directly from surface waves in order to generate electricity. They take advantage of the natural waves created by wind blowing over the ocean surface. As waves move towards shorelines they increase in height and power, providing a renewable source of energy that can be harnessed using wave energy converters. There are several types of wave converters that have been developed to capture this renewable energy source.
Oscillating Water Column Devices
One common design is the oscillating water column device. It consists of a partially submerged chamber or tube open to the ocean. As incoming waves rise and fall, so does the water level inside the chamber. This causes air pressure inside to fluctuate as well. Wave Energy Converter The motion of the air is used to drive an electrical generator either directly or through the use of turbines. Some oscillating water column devices allow the water level inside the chamber to vary significantly with the waves while others simply allow a thin sheet of water to move up and down inside the chamber. However they operate, the basic principle of converting wave motion into fluctuating air pressure and electricity remains the same.
Overtopping Devices
Overtopping devices capture wave energy by allowing waves to partially fill an elevated reservoir. As waves enter the reservoir they generate hydraulic head, the pressure due to the weight of the raised water. This hydraulic head is then used to drive a low-head turbine generator located at the base of the reservoir. When the tide recedes, the water in the reservoir drains back to the sea through the turbine, spinning it and generating power. Overtopping devices can effectively harness the power from large waves in shallow coastal areas. They have proved capable of operating reliably for long periods of time.
Attenuators
Attenuator type wave energy converters are floating structures moored offshore parallel to wave fronts. As incoming waves cause the long cylinders or plates making up the attenuator to rise and fall, the motion is used to drive an electrical generator, usually based on a hydraulic transmission system. The Columbia Power Technologies C-10 Attenuator constructed in Australia is a good example. It consisted of a 50 meter long floating barrage containing 10 individual “paddles” that rose and fell with the waves. Motion was transmitted via hydraulic pistons to generators positioned on the seafloor below. Although Columbia discontinued work on the C-10, attenuators show potential as a reliable form of commercial wave energy conversion.
Point Absorbers
Point absorber wave energy devices are small floating structures that capture waves from all directions as they radiate out from the point of disturbance caused by wind and waves. Typically spherical or cylinder shaped, point absorbers rise and fall with wave motion, utilizing the movement to drive an internal power take-off system. One advantage of point absorbers is their ability to effectively harvest energy from multi-directional waves in deeper waters further offshore where larger wave conditions exist. Their small size also allows them to be clustered into wave farms for utility scale power production. Emerging point absorber designs show promise but further technological improvements are still needed for commercial viability.
Power Takeoff Systems
Regardless of the type of wave converter, an effective power takeoff system is needed to transform the mechanical energy captured from wave motions into usable electric power. Common power takeoff methods include linear electric generators, hydraulic pumps connected to electrical generators, pressure oscillators driving hydraulic motors and linear generators, and others. Power electronics are also required to convert the variable frequency alternating current output into a steady grid-compatible frequency. Advancing power takeoff and power conversion technology is key to optimizing the efficiency and reliability of commercial wave energy systems.
Environmental Impacts and Benefits
As with all new energy technologies, the environmental impacts of wave converters must be properly evaluated. Several studies have been conducted to assess how wave farms and individual ocean devices may affect marine habitats, species behavior, water quality, and scouring of the seafloor. Impacts are generally localized around device installations and most effects appear minimal if wave energy projects are sited carefully. Some potential benefits include providing hard substrate habitat for colonization, acting as artificial reefs, and protecting coastal areas from erosion by attenuating wave energy. Overall, wave power shows potential as clean renewable resource that has far less impact on the ocean environment compared to conventional offshore oil and gas development.
Progress Towards Commercialization
After decades of research and development, wave energy technology is gradually advancing towards commercial viability. Ongoing projects include seabed-anchored wave farms in Europe utilizing multiple attenuator or point absorber devices to achieve utility scale multi-megawatt installations. Device optimization through further open ocean testing is needed to validate performance over the long term in real sea conditions. Investments are also being made to further engineering design and scale up promising prototype technologies. Although not yet competitive on a large scale, wave power costs are declining as the industry gains experience building and operating wave energy projects. With continued technology innovation and demonstration, wave energy could play an important role as a renewable resource, providing clean power to coastal regions around the world.
Many technological designs have been developed to harness the abundant renewable energy contained in ocean surface waves. From oscillating water columns to attenuators to point absorbers, wave converters offer a means to tap into this vast resource. Although significant engineering challenges remain before wave power achieves widespread commercial viability, ongoing progress shows the sector is advancing steadily towards providing clean electricity on utility scales from the ocean. Continued research, development, testing and demonstration of wave energy technologies will be crucial to achieving
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1. Source: Coherent Market Insights, Public sources, Desk research
2. We have leveraged AI tools to mine information and compile it.
