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Seafloor carpet mimics muddy seabed to harness wave power

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February 23, 2014

A rubber mat forms the 'carpet,' and sits atop a grid of hydraulic actuators, cylinders an...

A rubber mat forms the 'carpet,' and sits atop a grid of hydraulic actuators, cylinders and pumps

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Many organizations around the world are looking at ways to harness the power of waves as a renewable energy source, but none are covering quite the same ground as a team of engineers from the University of California (UC), Berkeley. The seafloor carpet, a system inspired by the wave absorbing abilities of a muddy seabed, has taken exploring the potential of wave power to some intriguing new depths.

Muddy seabeds have long been known to absorb the impact of ocean waves. When a severe storm strikes in the Gulf of Mexico, local fisherman make for areas where they know the ocean floor to be heavily laden with mud, as the softer sub-surface takes the sting out of the waves and provides respite from the storm and violently surging seas.

Drawing inspiration from this, the UC team set about devising a system where the energy would not only be absorbed, but converted to usable energy.

A rubber mat forms the "carpet," which while sitting atop a grid of hydraulic actuators, cylinders and pumps, takes on the motion of the incoming waves. In moving up and down, the carpet creates hydraulic pressure in the cylinders, which is then piped back to shore to be converted to usable power.

Experiments conducted at UC Berkeley have shown that the carpet is capable of absorbing more than 90 percent of the wave's energy. According to the researchers, one square meter (10.8 sq ft) of seafloor carpet would generate enough electricity to power two US households, while 100 square meters (1080 sq ft) of carpet would provide the same power as a soccer field covered in solar panels (6,400 square meters or 68,889 sq ft).

Having tested experimental setups in the Berkelely laboratory, the team has turned to Expe...

“We plan to start testing this system in the ocean within the next two years, and we hope to have it ready for commercial use within the next 10 years,” said Assistant Professor of Mechanical Engineering at UC Berkeley, Reza Alam.

The team emphasizes the durability and versatility as strengths of the system. As it is seabed-based, made from flexible non-corrosive materials and intended to be installed in shallow coastal water about 60 ft (18 m) deep, it should be able to "survive the strong momentum of the stormy seas." The team says the system can be easily transported and its modular design allows it to be scaled up or down in width, depending on environmental and energy demands.

In addition to offering an alternate source of energy, the conversion process produces seawater at high pressure, which can be used for desalination and distributing fresh water, a potential boon for residents in coastal regions prone to drought.

Having tested experimental setups in the Berkelely laboratory, the team has turned to Experiment, a crowdfunding site for research projects, to drive the next phase of the endeavor. If their goal is reached, the team will develop a larger prototype to test performance and identify materials for real ocean applications.

You can hear from Alam and other brains behind the project in the video below.

Source: University of California, Berkely

About the Author
Nick Lavars Nick was born outside of Melbourne, Australia, with a general curiosity that has drawn him to some distant (and very cold) places. Somewhere between enduring a winter in the Canadian Rockies and trekking through Chilean Patagonia, he graduated from university and pursued a career in journalism. He now writes for Gizmag, excited by tech and all forms of innovation, Melbourne's bizarre weather and curried egg sandwiches.   All articles by Nick Lavars
8 Comments

Congratulations. This is simply the best invention on gizmag in the many years ive been visiting. Well done! Roll out the green carpet

Dweezil Speedy
24th February, 2014 @ 02:17 am PST

I crunched the numbers. At 100% efficiency and 4 (one foot high) waves per minute those two houses would receive .75 KW per day (apiece) Thats one cold/dark house that I dont care to live in. Nuclear power is the only rational energy source, people.

JBar
24th February, 2014 @ 04:18 am PST

Interesting but not cost effective.

Slowburn
24th February, 2014 @ 06:10 am PST

The sea is a brutal environment. Corrosion. Fouling. It will be interesting to see how the cylinders, actuators, and pumps perform in the real world. The beach is less than an hour away. Get the prototype in the water!

Bruce H. Anderson
24th February, 2014 @ 08:57 am PST

JBar: If by 0.75KW per day you mean 18kWh per day, then the place is not necessarily as cold and dark as you think. Only if you take a typical suburbian waste bin built by today's sad construction standards. But there is a different set of standards out there, one that would get your place both warm and lit up, it's called passive house. These things have been developed since the late 80's and the best of them (even back then) were warm and cozy in cold German climate heated by what's roughly the equivalent of the body heat of its inhabitants (aka no additional heating system, in winters that go to -20degC). That's two orders of magnitude less that what you are using to make your argument for nuclear power.

BeWalt
24th February, 2014 @ 09:56 am PST

Interesting idea. Having spent my life at sea,I can only hypothesize that you would have better luck holding back the tide than create a profitable wave energy machine. The ocean is the most inhospitable environment on earth for man made equipment. Another thing to consider is the destruction of habitat that would occur by installing these things. Many or most marine organisms also use electric currents to navigate,breed,find food,and other life functions. Lastly,wind creates waves.Why dont we take energy from the source? The Dutch have been doing it for centuries

captinsano
25th February, 2014 @ 05:27 am PST

I'm sure it will work for a while but as others have pointed out the ocean is a very severe environment. I suspect maintenance costs will outweigh any efficiency of energy production. One good storm could easily rip out the whole apparatus. I remember a popular dive site along the Gulf coast. It was a 50 foot steel hull buried completely in the sand five miles off shore. After a big storm the hull was dug up by the current, broken to pieces, and scattered over several miles. Between the corrosion, sediment, barnacles, storms, and currents I don't think this design will last very long.

Bob
25th February, 2014 @ 08:25 am PST

Some good observations here Bob, and you may be right.

However, if steps were taken to protect the assets by seawalls or barriers of some type, major damage may be prevented.

My thought is: Why not vector the pipes that convey the water force from ocean to shore, and by doing so vastly multiplying the power at the output end?

John English
26th February, 2014 @ 03:06 am PST
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