Good Thinking

CorPower system gives wave power the gears

CorPower system gives wave pow...
CorPower Ocean's wave power-harnessing buoys utilize a geared drivetrain instead of hydraulics (Image: CorPower Ocean)
CorPower Ocean's wave power-harnessing buoys utilize a geared drivetrain instead of hydraulics (Image: CorPower Ocean)
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CorPower Ocean's wave power-harnessing buoys utilize a geared drivetrain instead of hydraulics (Image: CorPower Ocean)
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CorPower Ocean's wave power-harnessing buoys utilize a geared drivetrain instead of hydraulics (Image: CorPower Ocean)
Each buoy is moored to the sea floor, although sitting on the line part way between the buoy and its anchor is the actual wave energy converter mechanism (Image: CorPower Ocean)
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Each buoy is moored to the sea floor, although sitting on the line part way between the buoy and its anchor is the actual wave energy converter mechanism (Image: CorPower Ocean)
The drivetrain uses multiple small pinion wheels to convert linear motion into rotation, spinning up a flywheel (Photo: KTH)
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The drivetrain uses multiple small pinion wheels to convert linear motion into rotation, spinning up a flywheel (Photo: KTH)

Harnessing wave power can be a tricky business. It's one thing to build a device that simply moves up and down with the waves, but another to build one that's efficient enough to be cost-effective. Swedish company CorPower Ocean claims to have done just that, however. Its wave energy converter buoys reportedly generate five times more energy per ton of device, at a third the cost of other wave power systems.

The CorPower setup is what's known as a point absorber system. Here's how it works ...

A buoy floats on the surface of the ocean, moving up and down with the waves. That buoy is moored to the sea floor, although sitting on the line part way between the buoy and its anchor is the actual wave energy converter mechanism.

Each buoy is moored to the sea floor, although sitting on the line part way between the buoy and its anchor is the actual wave energy converter mechanism (Image: CorPower Ocean)
Each buoy is moored to the sea floor, although sitting on the line part way between the buoy and its anchor is the actual wave energy converter mechanism (Image: CorPower Ocean)

In some other point absorber systems, this consists of a hydraulic pump that generates electricity as it's pulled up and released by the buoy. In the CorPower system, however, there's a geared drivetrain, developed at Sweden's KTH Royal Institute of Technology. That drivetrain uses multiple small pinion wheels to convert linear motion into rotation, spinning up a flywheel.

Additionally, the drivetrain is said to enhance the buoy's movements, allowing it to rise and fall more while staying in sync with the rhythm of the waves. According to CorPower CEO Patrik Möller, this means that the system harnesses wave motion "all the way between the wave crest and wave trough and back in an optimal way, no matter how long or high the waves are."

Energy is temporarily stored onboard, before being output at a smooth and consistent rate via electrical cables running to the shore.

According to KTH, the buoys/converters are lightweight, compact, and relatively inexpensive to manufacture. One 8-meter (26-ft)-diameter buoy should be able to produce 250-300 kilowatts in a "typical Atlantic environment."

The technology was recently awarded €100,000 at MIT's Building Global Innovators Demo Day. A pilot project using the buoys is planned for this November.

Sources: KTH, CorPower Ocean

7 comments
owlbeyou
This is brilliant. Harnessing wave motion has an enormous potential. I imagine it would have to be installed in an ideal ocean depth that is close enough to shore but far enough to catch decent sized waves. If enough of them were installed, no temporary storage would be required since they would generate en masse a more consistent electrical output. If situated in places where the ocean has constant wave motion, they can be as reliable as wind turbines or better. An automatic depth-gauge compensator could self-adjust to the high and low tide levels at an always optimally located height to harness the maximum possible wave energy.
Jay Finke
Is this messing around with Mother nature ? I can tell you what doesn't effect winds and tides, SOLAR !
aajay
Just like all other wave power technologies, the biggest issue will be environmental approvals as some tree hugging person or group will complain and delay the project because the government doesn't have guts to tell them to get real and go away. This is the Australian conundrum anyway. Ruled by those who whinge the most and know the least.
Scott in California
At aajay: check out Carnegie Wave Energy in Perth. They have a longterm project underway, and have just hooked up to the grid. As a longterm student of OWEC (ocean wave energy conversion) I can tell you that the first problem with the CorPower system is too little volume of buoyancy per dollar of cost. Low cost buoyancy is the necessary factor to make successful OWEC. In addition, electric power generation must be on shore...otherwise, the cost and maintenance of small (the CorPower is too small...4.5 megawatts is the optimum generator size) electric generators in seawater is too severe..uneconomic.
Bob
Same problem as always with ocean power, storms, currents, and vulnerable cables to shore. It also seems kind of complex(too many gears) for a water powered electric yo-yo. Throw in salt water corrosion, barnacles, and weeds snagging the lines and you will have a lot of maintenance.
Anthony Parkerwood
I would have put the generator on a floating platform with the anchor wire on a drum attached to a ratchet drive to turn the generator with a flywheel. Easier to maintain.
Bob
I like Anthony"s idea but flywheels don't like to be pitched back and forth and you still have to run the power cable from the generator to shore. It would endure a lot of flexing if run to a moving floating platform. Sounds good at first but may actually mean more maintenance. However, something like a floating generator platform with some sort of wireless power transmission would be great if it could be done. Something that could be towed to safety when the next hurricane or nor'easter comes.