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Wind turbines generate unpredictable power – often at far less than capacity

Posted 14 December 2016 at 10:54 pm

Editor:

We have heard a great deal about the “200 mW Lighthouse Wind” facility proposed for Niagara and Orleans counties. I have several issues with this unrealistic statement of power to be provided.

First, the installed 1,749 megawatts (mW) of wind capacity currently installed in New York State generated an average of 455 mW in 2015, or 26 percent of installed capacity. (US Dept of Energy)

For the Lighthouse Wind project, an installed capacity of 200 mW will therefore yield an average of 52 mW. Confirming this number is Lighthouse Wind’s own statement that “up to 53,000 households” will be served.  Using data from the US Energy Information Administration for average household electrical consumption per month in New York State, average output of 46 mW from Lighthouse Wind may be calculated. This significant reduction from installed capacity is largely due to wind speeds which average below the speed necessary to generate a turbine’s full rated capacity.

In fact, if the wind speed is one-half of the turbine’s speed at rated capacity (typically 22 to 25 MPH), the output is one-eighth of the rated capacity. (Massachusetts Institute of Technology).

Second, the average output of 46 to 52 mW expected from the Lighthouse Wind project is gross output; we need to deduct from that output the power consumed by the wind turbines for yaw control, blade pitch control, blade de-icing, power consumed to start the blades spinning (at about 7 MPH wind speed), computers, nacelle heating and dehumidification, oil pumps, etc.

How much should this deduction be? The wind industry won’t divulge these numbers. “Trade secrets”, we are told. Governor Cuomo is asking us to endure tremendous devastation to our area for the sake of a measly 50 mW or so of power.

Third, the “Capacity Credit” – the percent of rated capacity which can be relied on without causing disruption to the electrical grid – is historically in the neighborhood of 10 percent to 15 percent of installed capacity, largely due to the variability of wind. (Midcontinent Independent System Operator)

In other words, we can depend on 20 to 30 mW of output reliably from the 200 mW Lighthouse Wind project, again minus that secret internal power consumption. This means that 170 to 180 mW or more of fossil-fuel capacity must be sitting idling, with all its necessary employees, ready to be placed into action when the wind dies down.

You can’t just decide to start up a fossil fuel plant from a cold condition when needed, so it sits idling at less than peak efficiency, cycling up and down as the variable electrical output from wind turbines changes, pumping out CO2 at a rate much higher than it would if it were allowed to run at a fixed or nearly fixed rate.

AWEA’s statistics on the amount of CO2 emissions reduced by wind turbines do not take into account the increased CO2 emissions resulting from inefficient use of fossil fuel power generation caused by reliance on wind power.  On Christmas Eve of 2004 in Germany, the system operators had to scramble to keep the grid from crashing when power generated from wind dropped from 6,000 mW to 2,000 mW in ten hours, at one point dropping by 16mW per minute. Soon after this experience, the operator announced plans to add 26 new coal-fired electric generating stations to ensure grid stability, calculating a capacity credit of only 8 percent from wind.  (German grid operator E.ON-Netz)

Germany’s experience shows that wind power will never replace generation facilities using fossil fuels, only supplement them when the wind is available.

Steve Royce

Appleton