The press often prints this inflated fiction as truth. It's actually a throwback to the 1940s and early 1950s, and was used by the nuclear industry as a public relations tool to make that source of power seem warm and fuzzy. As most people should know, residential use is only one of the demand segments for electricity. Commercial, industrial, and public sector users constitute majority demand.
All conventional sources of power produce their rated capacity—their optimal performance—when dispatched to do, changing their rate of performance only when asked.
The energy produced by wind machines is not dispatchable or controllable (except when they are shut down). A wind turbine is designed to generate optimal electrical power relative to its size, shape, ability to withstand stresses, rotor sweep and efficiency, and location, among other conditions. The wind needs to blow 8-14mph before a turbine will produce electricity, and a turbine is programmed to stop when the wind velocity exceeds 50 or 55 mph to prevent harm to its gears. If the wind were to blow at a sufficiently consistent velocity all the time and the turbine never broke down, the turbine would be operating at 100 percent of its capacity potential—its rated capacity. However, because the wind is intermittent and volatile, and the turbines at various times require maintenance, they actually will produce electricity only some of the time.
Whatever energy the wind turbine produces is always a function of the cube of the wind speed. Consequently, small changes in wind velocity produce major changes in the wind energy. Using a combination of considerations, such as meteorological testing, weather history, the history of turbine effectiveness, among others, energy experts assign a capacity factor for each turbine model, which predicts the amount of electricity a turbine will actually produce in a year.
No existing windplants located in the PJM (Pennsylvania, New Jersey, Maryland) region have achieved a capacity factor of more than 30 percent. Therefore, conventional generators provide over 70% of any wind turbine's rated capacity. About 60% percent of the time, a wind project will produce less than its capacity factor. It would rarely produce its rated capacity. And about 15-20 % of the time, particularly at peak demand times, it would generate nothing. Whatever it does produce would be continuously skittering; no one can know how much energy any wind project will produce at any future interval.
Consequently, a windplant rated at 40 MW, for example, will generate electricity in the neighborhood of 11-12 MW (25-30 % of its rated capacity).
Consider the following example.
Recently, a wind developer claimed his proposed 40-megawatt windplant would generate enough electricity to power 33,000 homes. A megawatt (MW) is one million watts or one thousand kilowatts (kW). According to the Department of Energy, the average home consumes 12,000 kW hours of electricity annually. In Maryland, the average home use is 13,000 kWh. Using the national average estimate of 12,000kWh, one can rather easily obtain a reasonable annual projection for the number of homes this windplant might power, if it produced at a steady rate. The following example assumes a 24-turbine windplant with 400-foot tall turbines, each rated with a potential of 1.65MW and with a generous capacity factor of 30 percent:
- 1.65 MW x 30% capacity factor = .50 MW (or 500 KW)
- 500 KW x 24 hours x 365 days = 4, 380,000 KW hours per year per turbine
- 4,380,000 KW x 24 turbines = 105,120,000 KW hours annual plant output
- 105,120,000 KW / 12,000 KW hours average household use per year* = 8760 homes powered annually.
Consequently, a 40 MW windplant, if it produced at a steady rate, would power less than 9,000 homes annually. But wind rarely produces at a steady rate. Because electricity from wind is inherently intermittent and volatile, it would only "serve" those homes where the occupants were willing to have electricity only when the wind was blowing in the right speed range—or for them to invest in an expensive battery storage system, which would require about 20 years of use to offset the cost, far longer than the equipment itself would last. Wind energy would service no homes in any conventional sense of that term's use.
The Mid-Atlantic region requires the PJM grid to supply many millions of households; it generates over 140,000 MW at peak demand times. A windplant with a rated capacity of 40 MW might on average deliver about 14 MW. As shown in the earlier example, this would provide electricity to about 9,000 households--if it weren't so unreliable and variable. Even so, notice how statistically negligible this amount is, virtually meaningless in terms of cleaner air and improved health—.0000858 of one percent of the PJMs production.
The reality is that wind technology at industrial scale can provide energy for no home, no industry, no commercial establishment, no hospital or police station or traffic system—consistent with today's standards of reliability and performance.
< Back to List | Claim #5 > |
