Final Four Qualified Team Technical Summaries
Since the August 2015 announcement of the Wave Energy Prize Qualified Teams, we have highlighted 16 of the teams’ technologies in our e-Newsletter. Below, in their own words, the final four Qualified Teams provide us with a look at the breakthrough technologies they are developing.
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Super Watt Wave Catcher Barges take full advantage of economies of scale and use proven low-cost components. They use an ocean-going barge to catch as much vertical wave pressure as possible with one structure, one mooring system and one export power cable. They are moored vertically and horizontally. Their vertical mooring legs turn large diameter uni-directional pulleys that "store torque" in large recoil springs located inside large diameter flywheels. These flywheel/recoil spring combinations uniformly unload their "stored torque" to four low-torque, low-RPM, high-output direct-drive wind turbine generators located onboard.
The generators take advantage of sea water cooling for further cost, space and weight reduction. The power can be converted onboard or delivered directly to a Lazy S export power cable that is connected to a local power hub for further power farm conversion. The vertical mooring system loads are reduced automatically to a maintenance top tension during storms, and the barge rides out the storms on its horizontal mooring system. After the storms pass, the vertical mooring system is reengaged and the power generation, of up to four six-megawatt turbine generators, is resumed. CAPEX and OPEX are similar to onshore wind power.
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Wavefront Power's Very Large Flapper Array (VLFA) is being developed for utility-scale power production from deep water ocean swell waves. The design will introduce a number of innovative, patent-pending technologies that will enable the economic capture of deep water wave power for the first time. Operating at depths up to 100 meters, the device is expected to be rated at approximately five megawatts, with a capacity factor of 48% based on an annualized average wave density of 30 kilowatts per meter.
The VLFA generally falls into the oscillating wave surge converter category of wave energy converters. While intellectual property concerns prevent us from disclosing many of the VLFA's internal mechanisms, general operation is characterized by a conversion of the kinetic energy from wave swells into electrical energy through a power conversion chain. This includes a hydraulic power take off, hydraulic motor and electrical alternator.
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WECCA has developed its patent-pending Advanced Wave Energy Conversion System (AWECS), comprised of three articulating barges securely anchored off shore. The device has survived nine years of wave energy converter platform concept testing off the west coast of Ireland. The fore and aft barges are propelled by continuous, undulating, emission-free, ocean waves surrounding the world's continents. Power take-off devices are connected at leveraged hinge points to the center barge via robust hinges. The relative motions of the fore and aft barges—compared to the weight-dampened center barge—provide opportunity to cost-effectively
capture and transform ocean wave energy into electricity. AWECS electricity is then conditioned for local grid requirements.
The AWECS is constructed from lightweight, durable composite material that provides strength, maintenance advantages and long-term environmental cost benefits to operators and consumers. Designed to constantly sense and dynamically tune its physical characteristics, the system is able to extract the maximum energy through resonance relative to changing wave climates. When hazardous storm conditions are sensed, the AWECS is designed to submerge to safe depths, until storm conditions subside, then surface again to generate electricity.
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The Archimedes Waveswing™ is a submerged point absorber wave energy converter that uses the change in pressure caused by passing waves to expand and contract a volume of air that moves a large piston. The piston is connected to a linear generator, which converts the relative motion of the two parts directly into electricity. The unique operating principle of the device provides a gearing effect that amplifies the effective wave height, thus producing a highly effective point absorber. The device is tension-tethered to the sea bed anchor via a structural leg, which also carries a flexible power cable for export of
electricity ashore.
The device was originally invented in 1994 by Fred Gardner in Holland, and a previous large-scale variant was tested offshore Portugal. Recent innovations have enabled down-scaling of the concept, improving the energy yield per unit volume, which in turn reduces the cost of power produced. Initial systems will be rated at 50 kilowatts and are designed to meet power needs in both isolated areas and island communities, where the cost of electricity is high. The technology is expected to progress to utility scale as learning is gathered through early deployments.
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