Wind power has limitations
August 29, 2008 · 10:16 AM
Wind turbines are the latest popular “answer” to our country’s energy problems with talk of three-bladed monsters covering vast areas from Texas northward. T. Boone Pickens is spending millions to promote his vision of generating 20 percent of our energy from wind power (although her refuses to install any of the turbines on his own 120,000 acre ranch).
Readers should be aware of wind turbine limitations. The number of wind turbines per square mile is restricted to between 5 and 8, depending on size, to minimize the propeller blade-wake effects between turbines. The most popular Danish turbine is capable of generating 600 KW power at optimum wind conditions. Ideally, it would take close to 1,700 of these turbines spread over more than 200 square miles to match the output of a 1,000 MW conventional power plant.
Unfortunately wind turbine power varies with the cube of the velocity reducing the 600 KW output at 30 to 40 mph, to 364 KW at 22 mph, 277 KW at 20 mph, and 124 KW at 15 mph. Thus, getting the 1,000 MW power at a wind speed of 15 mph would require nearly 8,500 600-KW turbines and 1,000 square miles.
The wind turbine power output variability would be less of a problem if there were some way to store power to meet demands during reduced wind conditions. Unfortunately, that capability does not exist. (Obviously solar power faces the same problem after “sunset”.)
The variability of wind power makes it very difficult for power companies to integrate wind power into their grid and still maintain the stable power supply required to avoid user-operating problems. This is a particularly severe problem if wind power is a large portion of the total power output.
Lacking storage capability, the only way that power companies can make up any short-term variations is to have natural gas powered turbines ready to come online within seconds. These types of quick response power generators are inherently less efficient than the standard gas powered devices. In addition, the generator costs are more expensive per unit of power generated.
In conclusion, wind power is not the panacea that some are suggesting. Power companies will have serious supply and cost problems if forced to generate a large portion of their power from wind turbines. The general public and in particular, power company customers, need to be informed.