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Biomimetic Ocean Power
Jeremy Faludi, 30 Oct 06
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Ocean power is a dark horse in the race for the future of energy--few people know much about it yet, but I predict it will be huge. I also love biomimicry, so I was delighted to discover BioPower Systems Pty. Ltd., a new company using biomimetic designs to generate power from the ocean. They have two main designs--the BioWAVE, which imitates kelp fronds, and the BioSTREAM, which imitates shark or tuna tails.

Both designs are meant to oscillate back and forth in ocean currents rather than rotating like a turbine, and they use a proprietary drivetrain to convert that low-speed high-torque oscillation into high-speed low-torque rotation of a permanent magnet motor. (No doubt a gearbox and a mechanical rectifier.) Oscillating instead of rotating makes them much less dangerous to sea creatures; the only possibility of harm to fish and other creatures is them getting smacked by a device, which is unlikely, since the waves that push the devices will also be pushing the fish in the same direction. Even the base that holds these devices to the ocean floor is biologically inspired in its design--rather than having a single beefy piling, it has many small "roots" bolting it to the seabed. This way installing the system is easier and cheaper--it "does not require large specialised vessels or drill rigs due to the small gauge of each bolt."

BioPower says the BioWAVE (kelp-like) generator captures the widest and deepest swath of wave energy of any device that does not require a huge rigid structure. It also rotates freely, so it automatically orients itself to the wave direction to maximize output. In storms, it can also lay itself flat on the ocean floor to avoid the extreme forces which would rip apart a rigid generator. (Or which would require a rigid generator to be massively overbuilt and more expensive.)

The BioSTREAM (tail-like) generator is basically an active weathervane, which changes its pitch to make the waves push it around. While not as big as the BioWAVE, it should be more efficient: they say "The motions, mechanisms, and caudal fin hydrofoil shapes of [shark, tuna, and mackerel] have been optimised by natural selection and are known to be up to 90% efficient at converting body energy into propulsive force." Presumably when you reverse it to convert the propulsive force of waves to energy, the efficiency is just as good. The BioSTREAM would also self-orient to the waves, of course, and in rough seas can "assume a streamlined configuration to avoid excess loading". They say they are developing the system in sizes from half a megawatt to 2 MW.

At first I thought these systems would be great to adapt to wind power as well (avoiding the whole bird-killing problem, the main objection to wind power). However, both of these systems require the fluid they're in to go back and forth--they use the power of waves, not the power of ocean currents. This is a fundamentally different ballgame than wind power.

In any case, it will be exciting to see where this goes. Their ideas are still just in the lab, but the company's Dr. Timothy Finnigan says, "The company is now planning to conduct lab-scale model testing, and follow this with a full-scale ocean-based pilot program in 2008. Commercial units are expected to be available in 2009."
Testing in the lab now, their first in-ocean tests are planned for 2008, and projected release into the real world is in 2009.

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Jeremy, thanks for a very interesting post. Do you think these designs have any advantages in resisting corrosion from salt water? Do you have a sense of their maintenance requirements?

Posted by: David Foley on 30 Oct 06

On converting this sort of thing to wind: one thought I've had involves extracting power via sails anchored with piezoelectric tethers. As the wind tugs the sail, the tether is stretched, and current flows.

(The sail is, of course, coated with PV material!)

Posted by: Tony Fisk on 30 Oct 06

Ocean Currents are great but I don't have one in my back yard. How about a scaled down version for homes on rivers and streams. Or a mid-sized model for city sewers. Scientists are always thinking too big. We don't need anymore giant things taking up space and mega-amounts of energy &c. Small scale easily built and/or assembled and/or hacked @ home. Cool ideas are all well and good. But getting environmentally sustaining and sustainable energy saving goods to suburban Home Depots and Wal-Marts(saints preserve us!) will do a lot more good than huge contractural projects that only serve a plutocratic elite rather than a small business which serves a wider is shallower spectrum of people.

Posted by: Jason Xanthopoulos on 30 Oct 06

But the smaller it is, the less efficiency you'll get in the long run. Even with transmission losses, large generating facilities are better then small scale setups. This only applies to turbines and engines. Solarvoltaics is different.

Posted by: Chris on 30 Oct 06

I am looking forward to their lab result. I really like this idea. as long as this company's equipment can generate economic power, then the generated power can be integrated into current power grid. therefore, all the people can use that. so I don't think we need to install a facility in our back yard:)

Posted by: keanu zhang on 31 Oct 06

Wave energy can certainly be an energy source for the future. However one should keep in mind the potential of different sources. The energy content in waves is estimated by the World Eenrgy Council to be around 2 TW. Current global primary energy use is currently about 15 TW and will probably be twice that in 2050.

Posted by: Rene Kleijn on 31 Oct 06

I don't think I understand the BioSTREAM. You are right that it won't work in the air, but I don't understand how it will work in the water. The BioWAVE moves because the waves move it back and forth, but the BioStream seems like it would point in the direction of the current, and that is it. I don't understand how it will create any torque unless the current changes in a side-to-side way, and that seems like it would be minimal. It is, after all, streamlined.

Posted by: J on 31 Oct 06

Very interesting. I remember a contest a few years back that gave out grants as awards to top inventions. This idea was drawn very roughly, and I believe placed in the top rankings for a grant. It is great to see the ideas get developed further, as we can tap a near free perpetual energy source.

How does the kelp like machine react to tidal changes? I would imagine it must have to adjust to the tide to keep the proper amount of tension to keep the generator moving.

Posted by: johnny sprada on 31 Oct 06

The idea is captivating. The actual results will be telling.

David Foley- excellent question. The company doesn't say this either way- but I present an idea that might just answer this in my treehugger article posted today. Also, the company is trying for lightweight biomimetic engineering- not sure what material they are going to use...

Posted by: Tim M. on 31 Oct 06

Great catch, Jeremy. Cool stuff.

Posted by: Jamais Cascio on 31 Oct 06

"At first I thought these systems would be great to adapt to wind power as well (avoiding the whole bird-killing problem, the main objection to wind power)." When I mentioned this problem in a post concerning wind power some time ago I was denounced as a shill for the oil companies. Glad that the desire not to slaughter birds for energy is not dead.
"Scientists are always thinking too big. We don't need anymore giant things taking up space and mega-amounts of energy &c. Small scale easily built and/or assembled and/or hacked @ home." Well, it isn't the scientists who think too big. It's the engineers and their corporations that look for the big deal with the big bucks for retirement. Large numbers of backyard machines, though somewhat less efficient per machine than the large ones (that, unfortunately, need large distribution systems), seem attractive to me. And, while the wind might be a "current", anyone watching flags flap around can tell that the direction varies rapidly and for extended periods. Maybe there IS a use for these in wind power...

Posted by: barry on 1 Nov 06

BioStream outwardly closely resembles an idea patented about 10 years ago. The basics are the same; there are a number ways such devices can extract useful energy from the motions of fluids. By the way, such things work in air if certain parameters are maintained (after all, air is just another fluid). The device is useful for more than just power generation; erosion control and thrust production are also part of the game. As for scale, these things are practiceable from centimeters to tens of meters (guppies to blue whales). While oscillating "tails" appear much less dangerous to animals than rotary props, remember that Orca can use their tail flukes to stun small swimming fish, so as with anything, it all depends on specific conditions. - Chuck Pell

Posted by: Chuck Pell on 6 Nov 06



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