Wind farms generate an awful lot more electricity than they consume. They need a little electricity for operation, but nothing compared to the amount that they generate
There are five things worth clarifying when talking about wind farms and the power that they generate vs what they consume.
- Wind turbine operational systems consume a little power
- De-icing systems barely exist
- Air-conditioning barely exists
- Starting the blades doesn’t require power on modern wind turbines
- Wind farms very little electricity for operation compared to alternatives
Let’s take each in turn.
Wind turbines consume a little power for operation
Wind turbines use electric motors to yaw the blades to point into the wind. They use electric motors to change the angle of the blades to the wind, something known as pitch control. These are occasional changes, not constant changes. It’s not like the wind changes direction and speed every minute, or that it’s worth adjusting the blades for minor gust changes. They get set based on the average wind direction and speed and left that way until substantial changes occur for the most part.
Turbines and wind farms also have sensors, computerization and SCADA interfaces. These are like the wiring in your car that allows your lights to go on and off, or the sensors that tell your automatic car wipers to start if there’s a sprinkle of rain.
Wind turbines have lights on the top which turn on at night so that they can be seen by air traffic.
Wind turbine manufacturers have a vested interest in accurate full lifecycle cost assessments (LCA) and publish these. The amount of electricity consumed in the full lifecycle is accounted for and is a trivial amount compared to the electricity generated.
Wind farm operators monitor this because they have to pay for electricity that they consume from the grid, and net energy generation is 99.7%+ Hepburn Wind is a community wind farm in Australia. Its Founding Chair, Simon Holmes à Court, has confirmed that over the first 11 months of operation, the wind farm generated 320 times as much energy as it consumed from the grid.
De-icing systems are just now showing up on wind turbines
In some northern climes in the winter time, ice does build up on wind turbine blades. This can reduce aerodynamic efficiency of the blades by a few percent. Wind de-icing systems are just starting to appear.
Among the highlights during the first day at Winterwind 2012 was a stage presentation of de-icing solutions by six of the world’s leading manufacturers. Five of these systems are brand new and some have yet to enter the commercial market.
Two years ago this session would have been unthinkable, the market just wasn’t there, says Göran Ronsten, program coordinator of Winterwind 2012.
The total number of orders for de-icing wind turbines referenced was under 1,000 and the total number working at that time was under 100. When de-icing is operating in wind turbines, it will be operating at a significant net gain for generation in harsh winters.
Wind turbines don’t use air-conditioning
According to Epuron spokesman Martin Poole, their wind turbines use simple radiators like those in cars to draw heat away from blades when they are operating and don’t air condition them at all. Consultation with several industry representatives confirmed that there are no known turbine designs in Australia that feature air conditioning.
There are cooling products for wind turbines, but they aren’t commonly used. Australia isn’t known for being a cool place, yet major wind farms don’t use cooling products.
Modern wind turbines start by themselves
Old US wind turbine designs used to use synchronous electric generators which needed to be spun up to generating speed before they could start creating electricity. A Vermont design in the less than 100 KW used this and they were erected around the USA in relatively small numbers range 30-40 years ago.
Denmark used asynchronous or induction generators from much earlier, and all larger wind turbines have used them for at least 20 years. These motors can generate electricity at any speed, which they then adjust to be the right frequency using electronics. Further, the blades change profile from the high-speed tip through the low-speed wider portion of the blade nearer the hub. The wider portion catches more wind and allows the greater torque at lower speeds to spin the blades. Pitch control, changing the angle of the blade to the wind, allows breaking and starting of the blades in different wind conditions without requiring significant electricity from the grid to start them moving.
Other forms of generation draw more electricity
All power stations draw power from the grid when they are not operating, and all draw power from their own generation when operating (known as parasitic or auxiliary load).
For coal-fired plants at least 20 years old, parasitic (i.e., on-site) power consumption can run as high as 7 to 10 percent of gross MVA generation.
in combined cycle [gas] power plant (CCPP.) the auxiliary power consumption fall in the range of 2 to 5 % of actual generating capacity.
Coal plants use 20 to 30 times more parasitic power than wind energy. Gas generation uses 7 to 17 times more electricity just to operate than wind energy.
So where does this leave us?
Wind farms use a tiny amount of energy from the grid compared to the amount that they generate. In fact, wind farms use much less electricity than standard generation plants.