World's Largest Wind Turbine

PeteJones writes "'Construction work on the REpower 5M was successfully completed last night with the installation of the rotor. Thus the main work on the prototype of the 5-megawatt, world's largest wind turbine has finally been completed.' The pictures are quite impressive. With 3 18-ton rotor blades pumping out 5 MW I wonder if my neighbours would mind one in my backyard?"

Wind power efficiency

[TheReckoning]

Does this sort of über-large wind power machine generate more energy than it takes to create, install, and maintain it? I remember reading that the smaller machines required more energy over their lifetimes than they were able to generate.

If that's becoming less true, I think this is a great thing. I worry a little about the environmental effects of "taking energy out of the wind", but I haven't read about anyone important who shares my worry, so it's probably unfounded.

Re:Wind power efficiency

[Lust]

negligible energy withdrawn compared to total power of atmosphere. may as well worry about effect of high-rises on wind patterns. Far more important things to focus on...

Re:Wind power efficiency

[jeti]

If that's becoming less true, I think this is a great thing. I worry a little about the environmental effects of "taking energy out of the wind", but I haven't read about anyone important who shares my worry, so it's probably unfounded.

The whole of Europe was once covered with forests. Now most of it is covered by farmland and urban areas, which offer less resistence to wind. If anything, those windmills will bring back more "natural" conditions.

Re:Wind Requirement

[general_re]

Any wind will spin it.

Any wind? Not unless it's frictionless and massless, my friend - overcoming inertia is not a free lunch.

Wow, only need 199 more!

[twitter]

5MW is impressive. Still, I'd like to put than number in perspective. It takes 200 of them to be the equivalent of one normal nuclear power plant, if and only if the wind blows continuously. The wind does not blow that way, it generally blows at off peak hours so power storage is mandatory. If that gets cheap enough this will be practical.

De-FUD'ing windpower.

[phkamp]

This site http://www.windpower.org/ which the danish wind generator producers have put up contains a lot of useful information about windpower and counters most of the FUD you'll hear.

Wind power is not perfect, but it is here now (as opposed to fusion energy) has no waste problem (as opposed to current atomics) has local and well understood failure modes (things break, fall down) Produce a lot of power when we need it most (wind is driven by energy from sunlight) and it is economically competitive.

The key to a sensible energy future is to not be fanatical for/against any one source, but to exploit them all where and how it makes sense.

Re:Wind Requirement

[Waffle Iron]

I'd like to hear someone explain why a turbine which allows 98% of the air to escape between the blades is a good idea?

It's probably more complicated than that. These things work more like airplane wings than rotary compressors. The entire mass of air moving near the blades is likely affected by vortices and other aerodynamic effects. You probably want to give each section of disturbed air enough time to move back out of the way before the next blade slices through. Cutting through the previous blade's vortex isn't likely to be very efficient.

Re:Wind power efficiency

[Cecil]

It usually takes longer for this unscientific, unfounded idiocy to pop up on a wind turbine story, but here you are. Congratulations. People like you make it clear you have never seen a wind turbine, have no concept of environmental conservation, and are just parroting anti-wind lies invented by people vehemently opposed to reducing dependence on oil.

BIG, SLOW MOVING BLADES DO NOT CHOP THINGS UP. PERIOD. The danger posed is extremely minimal. It's theoretically possible for a bird to run into one of the slim, slow-moving blades, and that would likely cause injury, just as if they had run into one of our fancy new all-glass-exterior skyscrapers. But more birds are killed every minute by deforestation and destruction of wetlands, than will be killed by this thing in its entire working lifetime.

Re:Wind power efficiency

[j3110]

I would also like to pose the question of different wind currents at different altitudes as being a problem. With a big diameter (about 126m in this case) you are fighting yourself. You are actually moving faster than the wind would push at a lower altitude, presumably. I'm not even considering that the wind generally changes direction when you get higher, but I think that's actually much higher.

With these premises, would you not think that there is one good optimum size of the blades, and you should probably just build taller tower systems suspending many smaller generators?

Another consideration would be energy required to actually build and deploy smaller vs larger.

Re:Wind Requirement

[imsabbel]

Cut in speed for this model is 2.5 m/s. Cut out speed 25m/s.

Re:Wind Requirement

[susano_otter]

More surface area means more mass, which means a beefier joint on the axle, which means yet more mass, which means an even beefier joint.

After a certain point, the returns start diminishing. Each extra dollar spent gets you less benefit than the one before it. After a while, you get less performance with more surace area.

Or you use new materials, if they exist.

Air travel stagnated for a very long time, because the alloys available to make airplane engines were too heavy. An engine block powerful enough to generate the thrust necessary to move a large plane full of passengers and cargo was too heavy to lift its own mass into the air, let alone the airframe, the people, and their luggage. It wasn't until the development of stronger, lighter alloys that air flight moved beyond the wood-and-canvas ultralights of the early 1900s.

If it was simply a matter of adding more surface area, we'd be powering the entire world off of one 3-mile diameter fan in Death Valley, that generated 17 billion kilowatts (or whatever) off of the breeze generated by a butterfly in Japan.

Re:Well,

[El_Ehmenopio]

They don't. PV cells pay for themselves in about 2 to 3 years, depending upon the technology. Solar panels will continue to pump out power for at least 30 years (that's the age of the oldest existing). In my experience though, after about 20 years, a cell or two in an array may wear out, and must be removed or at least shorted around. Cell destruction is caused by temperature fluxuations, oxygen seepage, and the occasional rock. Most of these can be controlled, or at least mitigated by buting the arrays in an enclosure. Some plastics will block certain spectrums of light, so it is goo to match the arrays, or at least the expected spectrum with the enclosure.( most glass panels only block the infrared, which is not the most energetic spectrum anyway.)

Re:Wind Requirement

[oxbow lake]

if it were frictionless the mass wouldn't matter. it might move really slowly, but any wind would make it spin.