Wind Turbine Power Output Legitimacy
To Fowler Community,
Why do certain farmers want to install commercial grade wind turbines? We all heard the claims about reducing our dependence on foreign oil, but commercial grade wind turbines utilize foreign oil and produce very little output. Our State Representatives and the U.S. Government have reported that wind turbines have roughly 30% efficiency.
Wind energy is a clean resource, but producing a commercial grade wind turbine versus the power output does not outweigh the manufacturing environmental damage. Wind is a variable source; it’s never steady or controllable so we can’t rely on a wind turbine industrial zone to supply our power requirements. You can’t make wind produce during peak times when the extra power is required!
So, are we installing wind turbines but still going to be burning the same amount of fossil fuel? Yes, because controlling the grid is very important and coal fire energy plants cannot easily ramp up or decrease power. Wind turbines supply intermittent power and causes grid fluctuation. To control the electric grid, electrical suppliers rely on spinning reserves. Spinning reserves are typically natural gas generators and the government should eliminate the inefficient wind turbines tax breaks because the spinning reserves are spinning anyway.
Let’s face the truth; wind turbines will not save us, but are making certain people rich. These companies get huge tax breaks paid for by you. The State of Michigan even classified them as moveable property to help provide tax breaks and the U.S. Government provides a 100% depreciation bonus.
Unfortunately, the Fowler area is targeted for a commercial wind industrial zone and the report below shows that wind turbines produce very low power and the claims by the wind turbines companies don’t hold true. What it’s all about? Well, you’re correct; it is about greening, the green “all might dollar”. So read the executive summary below and understand why you need to protect your community.
EXECUTIVE SUMMARY PRINCIPAL FINDINGS
"Analysis of electricity generation from all the U.K. windfarms which are metered by National Grid, November 2008 to December 2010"
The following five statements are common assertions made by both the wind industry and Government representatives and agencies. This Report examines those assertions.
1. “Wind turbines will generate on average 30% of their rated capacity over a year.”
2. “The wind is always blowing somewhere.”
3. “Periods of widespread low wind are infrequent.”
4. “The probability of very low wind output coinciding with peak electricity demand is slight.”
5. “Pumped storage hydro can fill the generation gap during prolonged low wind periods.”
This analysis uses publicly available data for a 26 month period between November 2008 and December 2010 and the facts in respect of the above assertions are:
1. Average output from wind was 27.18% of metered capacity in 2009, 21.14% in 2010, and 24.08%between November 2008 and December 2010 inclusive.
2. There were 124 separate occasions from November 2008 till December 2010 when total generation from the windfarms metered by National Grid was less than 20MW. (Average capacity over the period was in excess of 1600MW).
3. The average frequency and duration of a low wind event of 20MW or less between November 2008 and December 2010 was once every 6.38 days for a period of 4.93 hours.
4. At each of the four highest peak demands of 2010 wind output was low being respectively 4.72%, 5.51%, 2.59% and 2.51% of capacity at peak demand.
5. The entire pumped storage hydro capacity in the UK can provide up to 2788MW for only 5 hours then it drops to 1060MW, and finally runs out of water after 22 hours.
Other Findings have emerged in the course of this analysis in additionl to the Principal Findings which related to the testing of five common assertions. These other findings are listed below.
1. During the study period, wind generation was:
The discovery that for one third of the time wind output was less than 10% of capacity, and often significantly less than 10%, was an unexpected result of the analysis.
2. Among the 124 days on which generation fell below 20MW were 51 days when generation was 10MW or less. In some ways this is an unimportant statistic because with 20MW or less output the contribution from wind is effectively zero, and a few MW less is neither here nor there. But the very existence of these events and their frequency - on average almost once every 15 days for a period of 4.35 hours - indicates that a major reassessment of the capacity credit of wind power is required.
3. Very low wind events are not confined to periods of high pressure in winter. They can occur at any time of the year.
4. The incidence of high wind and low demand can occur at any time of year. As connected wind capacity increases there will come a point when no more thermal plant can be constrained off to accommodate wind power. In the illustrated 30GW connected wind capacity model with “must-run” thermal generation assumed to be 10GW, this scenario occurs 78 times, or 3 times a month on average. This indicates the requirement for a major reassessment of how much wind capacity can be tolerated by the Grid.
5. The frequency of changes in output of 100MW or more over a five minute period was surprising. There is more work to be done to determine a pattern, but during March 2011, immediately prior to publication of this report, there were six instances of a five minute rise in output in excess of 100MW, the highest being 166MW, and five instances of a five minute drop in output in excess of 100MW, the highest being 148MW. This indicates the requirement for a re-assessment of the potential for increased wind capacity to simulate the instantaneous loss (or gain) of a large thermal plant.
Energy consumption in wind facilities
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. The manufacturers of large turbines -- for example, Vestas, GE, and NEG Micon -- do not include electricity consumption in the specifications they provide.
Among the wind turbine functions that uses electricity are the following,
- 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)
- 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§
Could it be that at times 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.
Is there some vast conspiracy spanning the worldwide industry from manufacturers and developers to utilities and operators? 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.
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.
(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 a Yes2Wind 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.
Also, 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.