CrunchGear

I’m admittedly not the world’s most intelligent engineer (I work in engineering design in a company that makes aircraft hydraulics) — but I think I can offer some kind of opinion:

In theory, systems that generate power with motion and systems that generate motion with power are perfect mirrors of one another.

The most basic example I can think of would be an electric motor: If you provide power to an electric motor, it will rotate; and if you manually make that motor rotate, it will generate electric power. (That’s essentially how all electric generators work, in principle.)

Another example: the jet engines hanging from airplane wings — they are turbines that spin as the result of energy released in fuel combustion. Energy turns the turbines and produce wind. Wind-powered generators work on the same idea going the other way. Wind turns the turbine blades, and that energy can be captured (usually electrically… not so much wind to petroleum).

The idea of using the oceans for power has been tossed around for some time now. Because of the Earth’s moon, the tides produce flow steadily in one direction for half the day, and in the other direction for the other half. It’s an idea that gets a lot of attention because of that steady flow.

The biomimetic (new favorite word after “sphygmomanometer” and “dumpling” ?) design is attractive because we might be able to take advantage of design traits that have been somewhat proven through eons of natural evolution.

Still, someone should bring up this point: If we absorb energy from the movement of water currents, debris will not travel as much as it otherwise would. Imagine if wind-power were ubiquitous — that means pollen would not travel as far. But that’s basic thermodynamics. The best we can ever hope to achieve is to break even (1st law), and we’ll never even get that (2nd law).

I hope this helps. And if some better engineer wants to put me in my place, I welcome the learning.

Yeah I agree with Claudio. Essentially, propulsion systems and power generation systems are different only in direction, not principle. Just as you can apply electric current to a magnetic system and create rotational energy (an electric motor), you can also use rotational energy on that magnetic system to create electric energy (a generator). The parts and the physical laws are the same, the process is just reversed.

The question is not whether this system works or not; we know shark tails can move water, so we know water can move shark tails. The question to ask is how efficiently it works. This brings us to the whole philosophy of biomimicry: nature has improved the efficiency of these designs over millions of years, so we are unlikely to come up with anything better.

I guess how well it works depends on how the currents are moving, if they undulate up and down or side to side then this thing makes some sense, if they flow, like water through a tube then a turbine would probably work better.

My first thought when seeing this is that it would follow the up down motions of waves as they pass by. Gut feeling is that they could product lots-o electricity. Yes, they would slow portions of the wave that is in the viciinty of the tail but I think thats a very small fraction of the available energy.

I hope these scientists can get this bio shark tail (darn… slaughtered that one) funded! It would be cool to see work and if it doesn’t work then it will make for some fun diving in the far future!