This article – Wind farm system excels at remote monitoring and control – at HazardEx, writes that “new ethernet technology is being utilised by a wind power generating company to better maintain and control their installations.”
The device, which you can learn more about at the HazardEx link above, operates by “detecting the wind’s direction, the control system can use a motorised yaw gear to turn the entire wind turbine into the proper direction of the wind to maximise power generation.” For for the benefit of the novice (me), the article explains that “at the top of each windmill is a turbine drive train with an adjustable blade that typically turns at 10 to 15 RPM. The blades’ pitch can be changed to allow the windmill to adjust for different wind conditions. The blade shaft connects to a gearbox inside the housing, which steps up the shaft rotation to around 1500 RPM and turns a generator. Each windmill has a control box comprised of an Industrial PC and PLC enclosed in the top of the windmill in the housing. Sensors for wind speed, wind direction, shaft rotation speed, and numerous other items collect data and transfer it to the PLC.”
Again, those interested in this technology can visit HazardEx.
But all that is not the reason for this post. Having stumbled on to the technology article, I was reminded of a post I read a little while back at Eric Rosenbloom’s AWEO site. If you haven’t been there before, that’s a stop you’ll want to make. Lots of excellent material there for anyone looking to improve their knowledge of industrial wind.
The article I’m speaking of is “Energy consumption in wind facilities,” which is linked in the highlighted text for your convenience.
What struck me when I first read Mr. Rosenbloom’s article was the fact that these giant turbines require electricity to operate. I guess I should have known, with the flashing lights and all. But then, things like consumption are not usually found at AWEA (American Wind Energy Association) or in the LLCs developer’s brochure. There’s a lot of talk about energy production, but I don’t recall hearing a peep about energy consumption.
That’s what made Mr. Rosenbloom’s post stick with me. He points out that “large wind turbines require a large amount of energy to operate. Other electricity plants generally use their own electricity, and the difference between the amount they generate and the amount delivered to the grid is readily determined. Wind plants, however, use electricity from the grid, which does not appear to be accounted for in their output figures. At the facility in Searsburg, Vermont, for example, it is apparently not even metered and is completely unknown [click here].* The manufacturers of large turbines — for example, Vestas, GE, and NEG Micon — do not include electricity consumption in the specifications they provide.”
In Mr. Rosenbloom’s laundry list of energy consuming activities at industrial wind facilities, guess what shows up as the first two items:
- yaw mechanism (to keep the blade assembly perpendicular to the wind; also to untwist the electrical cables in the tower when necessary) — the nacelle (turbine housing) and blades together weigh 92 tons on a GE 1.5-MW turbine
- blade-pitch control (to keep the rotors spinning at a regular rate)
The very two items in the HazerdEX article that pointed me back to Mr. Rosenbloom’s article today. (My ADD really comes in handy now and then!) I contacted Mr. Rosenbloom explaining there were plenty of folks like me who hadn’t really thought about the consumption factor, and probably more who at least needed a little reminder, and he kindly gave us permission to use his work.
Here are additional “consumers” listed by Mr. Rosenbloom:
- lights, controllers, communication, sensors, metering, data collection, etc.
- heating the blades — this may require 10%-20% of the turbine’s nominal (rated) power
- heating and dehumidifying the nacelle — according to Danish manufacturer Vestas, “power consumption for heating and dehumidification of the nacelle must be expected during periods with increased humidity, low temperatures and low wind speeds”
- oil heater, pump, cooler, and filtering system in gearbox
- hydraulic brake (to lock the blades in very high wind)
- thyristors (to graduate the connection and disconnection between generator and grid) — 1%-2% of the energy passing through is lost
- magnetizing the stator — the induction generators used in most large grid-connected turbines require a “large” amount of continuous electricity from the grid to actively power the magnetic coils around the asynchronous “cage rotor” that encloses the generator shaft; at the rated wind speeds, it helps keep the rotor speed constant, and as the wind starts blowing it helps start the rotor turning (see next item); in the rated wind speeds, the stator may use power equal to 10% of the turbine’s rated capacity, in slower winds possibly much more
- using the generator as a motor (to help the blades start to turn when the wind speed is low or, as many suspect, to maintain the illusion that the facility is producing electricity when it is not,‡ particularly during important site tours) — it seems possible that the grid-magnetized stator must work to help keep the 40-ton blade assembly spinning, along with the gears that increase the blade rpm some 50 times for the generator, not just at cut-in (or for show in even less wind) but at least some of the way up towards the full rated wind speed; it may also be spinning the blades and rotor shaft to prevent warping when there is no wind§
Darn, the things look innocent enough!
Mr. Rosenbloom suggests that “it may be that each turbine consumes more than 50% of its rated capacity in its own operation. If so, the plant as a whole — which may produce only 25% of its rated capacity annually — would be using (for free!) twice as much electricity as it produces and sells. An unlikely situation perhaps, but the industry doesn’t publicize any data that proves otherwise; incoming power is apparently not normally recorded.”
He asks, “Is there some vast conspiracy spanning the worldwide industry from manufacturers and developers to utilities and operators?” and suggests: “There doesn’t have to be, if engineers all share an assumption that wind turbines don’t use a significant amount of power compared to their output and thus it is not worth noting, much less metering. Such an assumption could be based on the experience decades ago with small DC-generating turbines, simply carried over to AC generators that continue to metastasize. However errant such an assumption might now be, it stands as long as no one questions it. No conspiracy is necessary — self-serving laziness is enough.”
Where does that leave us? “Whatever the actual amount of consumption, it could seriously diminish any claim of providing a significant amount of energy. Instead, it looks like industrial wind power could turn out to be a laundering scheme: “Dirty” energy goes in, “clean” energy comes out. That would explain why developers demand legislation to create a market for “green credits” — tokens of “clean” energy like the indulgences sold by the medieval church. Ego te absolvo. ”
Footnotes to the article:
(One need only ask utilities to show how much less “dirty” electricity they purchase because of wind-generated power to see that something is amiss in the wind industry’s claims. If wind worked and were not mere window dressing, the industry would trot out some real numbers. But they don’t. One begins to suspect that they can’t.)
*There is also the matter of reactive power (VAR). As wind facilities are typically built in remote areas, they are often called upon to provide VAR to maintain line voltage. Thus much of their production may go to providing only this “energy-less” power.
†Much of this information comes from a Swedish graduate student specializing in hydrogen and wind power, as posted in aYes2Wind discussion. Also see the Danish Wind Industry Association’s guide to the technology. The rest comes from personal correspondence with other experts and from industry spec sheets.
‡An observer in Toronto, Ontario, points out that the blades of the turbines installed at the Pickering nuclear plant and Exhibition Place turn 90% of the time, even when there is barely a breeze and when the blades are not properly pitched — in a region acknowledged to have low wind resource.
§”In large rotating power trains such as this, if allowed to stand motionless for any period of time, the unit will experience “bowing” of shafts and rotors under the tremendous weight. Therefore, frequent rotating of the unit is necessary to prevent this. As an example, even in port Navy ships keep their propeller shafts and turbine power trains slowly rotating. It is referred to as “jacking the shaft” to prevent any tendency to bow. Any bowing would throw the whole train out of balance with potentially very serious damage when bringing the power train back on line.
“In addition to just protecting the gear box and generator shafts and bearings, the blades on a large wind turbine would offer a special challenge with respect to preventing warping and bowing when not in use. For example, on a sunny, windless day, idle wind turbine blades would experience uneven heating from the sun, something that would certainly cause bowing and warping. The only way to prevent this would be to keep the blades moving to even out the sun exposure to all parts of the blade.
“So, the point that major amounts of incoming electrical power is used to turn the power train and blades when the wind is not blowing is very accurate, and it is not something the operators of large wind turbines can avoid.
“[In addition, there is] the likely need for a hefty, forced-feed lubricating system for the shaft and turbine blade assembly bearings. This would be a major hotel load. I can’t imagine passive lubrication (as for the wheel bearings on your car) for an application like this. Maybe so, but I would be very surprised. Assuming they have to have a forced-feed lubrication system, given the weight on those bearings (40 tons on the bearing for the rotor and blades alone) a very robust (energy sucking) lubricating oil system would be required. It would also have to include cooling for the oil and an energy-sucking lube oil purification system too.”
–Lawrence E. Miller, Gerrardstown, WV, an engineer with over 40 years of professional experience with large power train machinery associated with Navy ships.
See, I knew this would get you thinking. For those of you who hear about the CO2 reductions, but can’t find concrete numbers to verify; folks looking for the list of fossil plants closing as a result of industrial wind; taxpayers at state and local levels trying to get our legislators to provide transparency regarding tax credit deals; or consumers just trying to find out how much it’s going to cost; this may end up being just one more item on the list of “take our word for it.” I hope not. I hope we hear from the wind developers, the AWEA or windplant operators who must certainly know all this detail in order to report their successes back to their Boards.
Unfortunately, one thing I’ve found in my rather short time posting at Allegheny Treasures – the wind industry tends to ignore certain issues, which I suppose they feel uncomfortable defending. I know if I were in a business that generated cheap electricity, reduced emissions by closing down fossil plants, hired folks by the thousands and tossed my profits back at customers and the communities that permitted my operation in their midst, I’d be shoving statistics up the noses of all the naysayers. Numbers would be my friend!
You see, we do hear from folks that believe industrial wind will be a valuable contributor to the energy needs in the US. We appreciate that we do, since it is only in discussing opposing views that we learn. We just hope one day that the industry itself will come off script and respond to the many unanswered questions we’ve posed. Maybe they could bring along some actual performance data and a list of the dirty old plants that no longer operate.
We’re here to learn! How about helping us out?
Again, we thank Mr. Rosenbloom for the courtesy he extended in allowing us to use his work.
AT Note: Mr. Eric Rosenbloom is a science editor and writer living in Vermont.