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New Generator Boosts Wind Turbine Efficiency 50%
MagnetDroid writes "A startup company based in Vancouver has developed a new kind of generator that could harvest much more energy from the wind. The design could not only lower the cost of wind turbines but increase their power output by 50 percent to as much as 100 percent, in some locations. Normally, when wind speeds drop, a turbine's engine becomes less efficient. The new engine, from ExRo Technologies, runs efficiently over a wider range of conditions. The design replaces a mechanical transmission with what amounts to an electronic one. Magnets attached to a rotating shaft create a current, but individual coils can be turned on and off electronically at different wind speeds." The company will begin field-testing a small, 5KW wind turbine by early next year.
TFA doesn't mention specific percentage improvements in efficiency. That was kdawson's contribution, and then only in the poorly-worded headline. TFA is claiming that the overall output of a given wind turbine could be boosted by 50% or more by altering the dynamics of the generator to make it more efficient over a wider range of wind speeds.
Basically, turbines are most efficient at a given speed, and efficiency drops off for anything outside of that, whether faster or slower. This new design attempts to address that by decreasing the amount by which the efficiency drops off at different speeds. The improvement in the efficiency curve boosts overall power output, as the turbine isn't as strictly limited to a given wind speed for peak efficiency as it was before.
You can never go home again... but I guess you can shop there.
But, we are all going to have to get over seeing them as ugly or migratory-bird killers for this program to work.
And to do my part, I'll point out as I do in most wind turbine threads that windmills are not significant bird killers any more. In fact the very worst wind farm ever, Altamont Pass, killed fewer birds per year than a typical 3-story office building. And that was combining multiple worst-case factors, like an outdated scaffold design that encouraged raptors to nest on them, smaller fast-moving blades that are proven to be more difficult for birds to see and avoid, and a highly disadvantageous location in a choke point for bird migrations.
Modern wind mills have monolithic poles with rounded tops that birds can't nest or sit on, and have much larger, slower moving blades* that birds can see and avoid. I believe now they also do some cursory environmental studies to make sure they aren't putting the windmills directly in bird migratory paths, but with the other two improvements this probably isn't even that big a deal.
I'm a bird nerd. I love birds. If you can accept the bird deaths caused by glass windows in cities, windmills are not an issue.
Oh, and I think they're rather beautiful. :)
*Largely for efficiency reasons, the bigger the blade the more efficient. IIRC, the way they choose the sizes for windmill blades these days is by what will fit on the largest legally allowed trailer. I've seen convoys of trucks, each with very long trailers, each carrying *one* blade.
The enemies of Democracy are
It's kind of like a transmission. It's actually also kind of like the reverse of the adjustable displacement engines in some vehicles.
In some cars, you have an 8-cylinder engine but can use 4, 6, or 8 cylinders at various times based on the amount of power you need to generate. It doesn't take 8 5 liters of displacement to maintain highway speeds, but getting up to them quickly may. Turning off cylinders not in use saves fuel by not burning it when it's not needed. Each cylinder only draws chemical energy to make kinetic energy as needed.
If you left all the coils engaged, you might have too much resistance to generate any electricity in light winds and too much to generate it efficiently in more moderate winds. Yet if you build a turbine specifically for only light or moderate winds, you don't get any additional power once it is maxed out.
This solution uses wind, but you can't just press down on a pedal and ask for more wind (well, you could ask, but you'd be disappointed most of the time). So what it does instead is it has a magnet-in-coil generator with separately activated coils. Each coil only draws mechanical energy to make electricity as the mechanical energy is available. The rest of the coils are left as open circuits. If there's enough wind to turn the blades with half the coils on but not all of them (or too slowly to make sense with all of them), then you just open the circuits on half the coils and the other half keep generating. Only the coils in a closed circuit generate current and present meaningful resistance to the turbine. As you have more wind, you generate more power up to the maximum. The maximum number of coils doesn't impede this turbine from generating less current when some wind is still available though, because it just disconnects the spare coils until they are needed.
Windmills don't have that luxury, so often are working at RPM's that are not optimum. This method (if it works) widens the optimum range.
Close but not quite what they're getting at. What they're doing is increasing/decreasing the resistance to keep the windmill in the optimum RPM range over a larger range of wind speeds. So at 5 mph, the blades might spin at 20 rpm and generate 2 MW. At 15 mph, with the new system the blades still spin at 20 rpm, but now generate 5 MW. As oposed to traditional generators, where it would be spinning at 30 rpm and only generating 3 MW.