What happens if you run an electric motor backwards? That is exactly what researchers Dr Steve Turnock and Dr Suleiman Abu-Sharkh from the University of Southampton asked themselves after they had successfully built an electric motor for tethered underwater vehicles, using funding from the Engineering and Physical Sciences Research Council.
The well-known answer to this question is that it stops being a motor and becomes a generator. Instead of using electricity to turn a propeller and drive the vehicle along, the flow of water turns the propeller, generating electricity. What’s new about the Southampton design is its simplicity. “This is a compact design that does away with many of the moving parts found in current marine turbines. It’s a new take on tidal energy generation,” says Turnock.
Most current tidal stream generators are essentially wind turbines turned upside down and made to work underwater. They often include complex gearboxes and move the entire assembly to face the flow of the water. For example, they turn a half a circle as the tidal current reverses direction. Gears and moving parts require expensive maintenance, especially when they are used underwater. This pushes up the cost of running the turbines, a cost that is passed on to the consumers of the generated electricity. The Southampton design does not need to turn around because the design of its turbine blades means that they turn equally well, regardless of which way the water flows past them. The blades are also placed in a specially shaped housing that helps channel the water smoothly through the turbine.
Another beauty of the Southampton design is that everything is wrapped in a single package that can be prefabricated so there will be few on-site construction costs. “Just drop it into flowing water and it will start generating electricity. It will work best in fast flowing, shallow water,” says Turnock, who foresees rows of these devices secured to sea floors and riverbeds.
Hey — every little bit helps. Simplicity pretty much always cuts costs.
Good. More renewable energy is always good. Now if they can just commercialize it and get it to market and producing.
Very cool…
Just line up rows and rows of this along every major river in this country and watch the electricity come pouring in.
What’s even cooler is the fact that if one is malfunctioning, the whole unit can be replaced for another while it’s repaired instead of shutting down the unit and repairing it under water.
I’m all in favor of these, but what is the environmental cost? What happens to the fish and other aquatic life that get sucked in (or entrained as they call it).
No no, don’t you all get it! It can be used to power ships! Think about it, you have two of these on the front of the ship with the water flowing through them generating the power….which in turn runs the back two propellers that move the ship forward….which forces water through the front propellers generating the power!
And for extra electricity on board you can have a bunch of solar cells that are lit with sun-like lights so they generate power!
It’s….so…simple!
“What happens if you run an electric motor backwards?” The motor runs backwards!
What happens when you remove power from a motor and replace it with a load? If it is the right kind of motor and if some force makes it turn then it acts as a generator.
Hard to give the article much credibility when it starts out with such a stupid statement.
It is hard to get excited about such a common sense design. It will work.
Common sense design is what makes the world function.
Bogdon (3) simple – just put a grid in front and the fish don’t get sucked in. Johnny (4) – I’m no expert physicist, but that sounds like a perpetual motion machine, which don’t work. a few flaws 1) I believe the motors would create some drag, possibly equal to the thrust they would create as propellers, negating the energy savings. 2) no system is perfect – you would lose some energy in both the turbines and the propellers, so the turbines couldn’t provide enough energy to move the ship. There may be more – if someone knows their physics better than me they can correct/ammend my statement here.
Hard to give the article much credibility when it starts out with such a stupid statement.
I was initially thinking the same thing, but relaxed when I saw the beginning of the 2nd paragraph: “The well-known answer to this question is…”
Checking the link, I see it is a “press release” on a “politics” site, so I’m surprised there is not more “fluff”…
I’m sure “Dr Steve Turnock” and “Dr Suleiman Abu-Sharkh” are getting kidded something fierce for supposedly asking themselves that question. [grin]
Ha ha #7… you must not have seen the tag on #4.
It is an interesting idea. But, ask any boat owner about the two happiest days of their life. #1 – the day they buy their boat. #2 – The day the get rid of it.
These turbines will have to be made very durable, which will raise the production costs. Then there is ongoing maintenance, will be a killer. Besides the corrosive affects of salt water (or water in general), there is the issue of sea life (someone mentioned fish). I’m thinking more of moss, barnacles, seaweed, and other life that attaches itself to the device.
Then there is the issue of garbage. What happens when a log, a plastic bag, or other large garbage gets sucked into the intake rotors? You would have to raise these things out of the water every day, clear the junk, scrape off the sea life, look for rust and corrosion, check for leaks, and on and on. Just like a boat… it is a never ending task.
The author mentions that they work best in fast flowing shallow water. Well the technology to exploit that source of energy has been around for hundreds of years. It is called the water-wheel. It used to power the textile industy of Scotland, New England, and northen England. Why not keep the generator in a dry shed on land and hook it up to a simple water wheel? It would be much cheaper, more reliable, and the water wheel can can sized to optimize the torque and RPM needed for the generator with the average water flow.
I’m no expert physicist, but that sounds like a perpetual motion machine…
Now you just need to get your sarcasm detector working…