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"We said, 'No, we're not convinced this makes sense,' " says Larry Cundy, director of development at MPR. But CWind convinced MPR to do some basic analysis of the design, and eventually the engineering firm agreed to build the prototype. "It's a very novel application, quite frankly," Cundy says. "It's really a stroke of genius."
Cundy says the biggest advantage of CWind's design is that it's easier and less costly to maintain over the lifetime of the equipment. When a gearbox on a conventional turbine fails, the turbine is knocked completely out of service. Getting a replacement gearbox takes a long time, and removing the massive device from the wind turbine's nacelle requires a large crane and many days of work. Every day the turbine isn't generating electricity for the grid amounts to lost revenue for the operator.
"On a friction-drive system with multiple tires, if you lose a tire, the others are still there," says Cundy, adding that replacing tires is quick--roughly a day's work--and that future designs will allow maintenance while the turbine is still operating. The same redundancy applies to the generators--if one fails, the others can still function. Cundy says that the small, off-the-shelf generators used in CWind's design can be obtained quickly and are installed fairly easily with the help of a small crane built into the nacelle.
Nayef says that the tires used are designed to last for three years, and replacing all the tires used on a two-megawatt wind turbine is expected to cost $30,000--or nearly $200,000 over 20 years. By contrast, gearboxes have an average life of six years and cost about $600,000 to replace, or nearly $2 million over 20 years. "We're going to be competitively priced with conventional gearbox wind turbines, yet we have the advantages of high availability, high efficiency, and all of the advantages that come with serviceability."
Last month CWind signed a manufacturing agreement with global auto parts maker Linamar, which has committed its McLaren Performance engineering team (of Formula 1 racing fame) to producing the two-megawatt prototype. As part of the 10-year contract, Linamar will also manufacture market-ready turbines, likely beginning in 2011. Nayef says work is already under way on five-megawatt and 7.5-megawatt designs aimed at the offshore wind market as well as remote onshore sites where easy maintenance becomes a key selling feature.
New direct-drive turbines promise to lower the cost of offshore wind energy.
A practical peace of lateral thinking, a good idea always seems simple after the fact.
This solution would lend itself to water wheels as its another application held up by the need for a large expensive gearbox, the outside rim of the wheel would provide the runner track for the generator tires power take off.
Perhaps this could produce a low cost solution for third world power needs
If the flywheel has a certain mass, wouldn't it partially condition the rate of change of velocity (and thus power output) of the generators?
Also, is the minimum windspeed necessary to begin operation higher, or is the mass of the flywheel/generating system no greater than existing generator/transmission systems? In which case the first query is not relevant.
Friction drive can't be as efficient as gears because of the FRICTION.
In this system, during operation, there is no slip and therefore no energy lost to friction. Friction is why the tires pressed up against the flywheel also turn when it does; that is the source of the name.
The real genius of this device is that if the speed suddenly increases (or decreases for that matter) then the friction coefficient is quickly overtaken and the tires merely slip, rather than coupling the speed change into the generators. A traditional design prevents this from happening with a gearbox - but this is hard on the gearbox, as the article says.
FYI - gears have friction too.
durs, isn't there friction between gears also?
what has happened with the design presented earlier this year which uses coil energizing and no gearbox? this reminds me of a carnival ride.
An ant is a great design, but it is too bad when it enlarges to the one with the size of an elephant
When we disassemble a toy car, we can find almost all parts of transmission are made of plastic gears.
When we enlarge the toy car for 200 times, if the plastic gears still work properly? Th answer is NO.
when the power that th plastic gear transmission is small, the plastic material can afford the stress
and the heat generated during the power transmission can dissipate fast enough, but when the power increases
for hundreds of times, the small contacting area between one pair of gear does not increase so many times and
the stress of the contacting area will be too big for the plastics material, which leads to the failure of plastic gears.
Another factor may influence the transmission is the temperature of the contacting area, when the power is too big,
the plastic material is not good in conducting heat and the temperature of the contacting area may be so high that it
begins to soften the plastic material.
the ratio of CWind may be too small to drive the generator when the wind speed is not high, so the CWind is good only when
the wind speed is high.
When the power increases from 65KW to 1000KW, the surface of tire may melt into solid state and the device fails to work.
Here we need to know how about the efficiency of the transmission between the tire and the flywheel so it is possible to
estimate the temperature of the tire surface.
Some article said the tire of the F1 racing car may slip the car under some situation because of the high temperature
of the tire surface.
The price of the CWind may be another problem, the total price of eight small-size generator may be much higher than that
of a single bigger generator, the cost to synchronize the eight unsynchronous power to the power grid also should be considered.
An ant is a great design, but it is too bad when it enlarges to the one with the size of an elephant.
This was a perfect analysis. Thank you.
Agree with you on the info as presented in the article. The problems with heat and limited slip you specified can be designed around. An outer drum, driving an inner drum with an inflatable boot with friction material attached. This method is already utilized elswhere. Provide torque and speed ramp control via air pressure to segmented boot.
I was thinking that an approach something like an automatic transmission for a car might work, the pressure/velocity of the fluid could be used to determine how many secondary rotors are connected, and pressures/velocities too high wouldn't be channeled to do any work, so gusts wouldn't hurt the equipment coupled to the main flywheel. Then you wouldn't need a computer to run the thing.
Gearbox is a complex part in wind turbine and this new design is expected to reduce cost and improve efficiency of wind turbine.
Dr.A.Jagadeesh Nellore(AP),India
Wind Energy Expert
E-mail: anumakonda.jagadeesh@gmail.com
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SirLanse
71 Comments
Wow a clutch
They invented a clutch.
The turned it inside out, but it is still a limited slip clutch.
Reply