Tuesday, 6 December 2016

Wind Turbines Use Electricity From The Grid

An educational post on Facebook

John Curtis Most people do not realise that these turdbines use a lot of parasitic power when they are not generating any output. I looked in to this many moons ago and attach below what I was able to ascertain. At that time I wrote to three of the big turdbine manufacturers to ask them if I was correct in my assessment but answer came there none - from which I believe that the actual situation may well be worse than my assessment.
Wind turbine parasitic consumption. 

I have been considering effects of parasitic power consumption by wind turbines, by which I mean power that they must use to stay functional even if there is no wind. The manufacturers do not give detailed information but I believe we can assess what is needed by using common sense. 

Actual figures may vary from what I am assuming, but I do not think that I am far off. If you have any other ideas I would be very pleased to have them. Below is a representative list of equipment and systems that require electric power, together with assumed power consumptions. I have assumed a basic 2 megaWatt for this study. 

Yaw mechanism to turn the rotor into the wind. 20kW
Pitch mechanism to adjust the blade angle to the wind 15kW
Lights, controllers, communication, sensors, data collection, etc. 10kW
Heating the blades during winter. 250Kw
Heating/cooling and dehumidifying the nacelle. 10kW
Oil heater, pump, cooler and filtering system of the gearbox 25kW
Hydraulic brake to lock the blades when the wind is too strong. 5kW
Thyristors for power conditioning and connection. 25kW
Magnetizing the stator to keep the rotor speed constant 25kW
Using the generator as a motor to help blades start to turn when wind speed is low or, as many suspect, to create the illusion the facility is producing electricity when it is not, particularly during site tours. It also spins the rotor shaft and blades to prevent warping when there is no wind. 50Kw. 
TOTAL Installed. 435kW.

Not all items will be used at the same time, although they may be. However, we can generously assume 50% usage, for a parasitic consumption of approximately 215 kW.

Turbine rated wind speed is 12 mps (Meters per second). Cut in speed is 4 mps. Rated power is 2 mW. Power varies as cube of wind speed.
Therefore Power at 4 mps is 2,000,000/3 x 3 x3 = 74kW 
Nett output is 74 – 215 = -141kW
Power at 5mps is 144kW Nett output is -71kW
Power at 6mps is 250kW 
Nett output is +35kW

This shows that the machine does not start to produce useful power until wind speeds reach around 6mps, assuming that 35kW from a 2mW machine can be considered as useful. 

Published figures for average wind speeds locally (Banbury area. It will vary depending on actual location) at masthead height are 6mps. 
There are subsequent losses such as transformer inefficiencies and transmission losses to take power from turbine to grid. We can assume approximately 6% to 15%, depending on the type of equipment and transmission line lengths. 

What this says is that the turbine is virtually useless even at average wind speeds and that we need considerably more than average in order to get any useful power output. On average we can expect to power about 12 electric kettles. Not bad for an investment of around £2.4 million!!

Note that the turbine ‘sells’ its power based on metering at the output unit and thus avoids the effects of transmission losses. Also, there is no charge made for power that is consumed when there is low or no output. In other words, charges are made based on gross output, not net output. 

And we do not even start to save CO2 emissions until we reach average wind speeds. What a huge con job is being foisted on us all.

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