Wind Turbine Payback in Sioux County, IA
Wind turbine payback in Sioux County
No. The turbine wears out before it pays for itself.
At 30 m, the height a home turbine tower usually reaches, the wind in Sioux County, IA averages 6.43 m/s (14.4 mph). A 10 kW turbine there would make about 22,891 kWh a year, worth $3,331 at IA's 14.55¢/kWh. Against an installed cost of about $100,000, that is a payback of 30 years, and the turbine is built to last about 20.
What to do in Sioux County
A home turbine is not worth buying for savings in Sioux County unless your spot is far windier than the county average, 8.1 m/s at the hub against 6.43 m/s here. Per kW, solar panels would make about 1,200 kWh a year here against the turbine's 2,289, so get a solar quote first.
What would have to change
- Power would have to cost 22¢/kWh, 1.5 times what IA pays now.
- Or the average wind at the hub would have to be 8.1 m/s instead of 6.43. A taller tower or an exposed ridge can add some of that; a rooftop never will.
Against the rest of IA
Sioux County is the 290th windiest of 3,144 US counties at turbine height; the national middle is 4.79 m/s. The windiest in IA is Dickinson County at 6.59 m/s, payback 29 years.
Month by month in Sioux County
April is the strongest month here, at 7.31 m/s and about 2,400 kWh. August is the weakest, 5.39 m/s and 1,294 kWh, so the best month makes 1.9 times the worst. November to March brings in 44% of the year's output in Sioux County.
| Month | Wind at 30 m | Output | Worth |
|---|---|---|---|
| January | 6.49 m/s | 1,982 kWh | $288 |
| February | 6.55 m/s | 1,826 kWh | $266 |
| March | 6.88 m/s | 2,226 kWh | $324 |
| April | 7.31 m/s | 2,400 kWh | $349 |
| May | 6.71 m/s | 2,122 kWh | $309 |
| June | 6.09 m/s | 1,672 kWh | $243 |
| July | 5.41 m/s | 1,304 kWh | $190 |
| August | 5.39 m/s | 1,294 kWh | $188 |
| September | 6.45 m/s | 1,891 kWh | $275 |
| October | 6.76 m/s | 2,149 kWh | $313 |
| November | 6.67 m/s | 2,026 kWh | $295 |
| December | 6.41 m/s | 1,931 kWh | $281 |
What a taller tower would buy
Measured at 10 m the wind in Sioux County averages 5.08 m/s; at 50 m it is 7.17 m/s. That gives a shear exponent of 0.214, typical of ordinary open country. Going from 20 m to 50 m takes output from 18,915 to 28,250 kWh a year, 49% more, before counting the extra cost of the taller tower. Why tower height decides it explains the shear behind these numbers.
| Hub height | Average wind | Output | Payback |
|---|---|---|---|
| 20 m | 5.89 m/s | 18,915 kWh | 36 years |
| 30 m | 6.43 m/s | 22,872 kWh | 30 years |
| 40 m | 6.84 m/s | 25,860 kWh | 27 years |
| 50 m | 7.17 m/s | 28,250 kWh | 24 years |
Counties around Sioux County
4 of the 6 closest counties are windier at turbine height; the windiest, Osceola County, averages 6.57 m/s.
- Lyon County, IA: 6.46 m/s, 23,112 kWh, payback 30 years (21 mi)
- Plymouth County, IA: 6.4 m/s, 22,669 kWh, payback 30 years (24 mi)
- O'Brien County, IA: 6.48 m/s, 23,260 kWh, payback 30 years (28 mi)
- Union County, SD: 6.4 m/s, 22,669 kWh, payback 30 years (30 mi)
- Lincoln County, SD: 6.46 m/s, 23,112 kWh, payback 30 years (31 mi)
- Osceola County, IA: 6.57 m/s, 23,922 kWh, payback 29 years (34 mi)
Sun versus wind in Sioux County
Sioux County gets 4.11 kWh of sunshine per square metre a day on average. One kW of solar panels here would make roughly 1,200 kWh a year; one kW of the turbine above makes 2,289. This is one of the rare places where a kilowatt of turbine out-produces a kilowatt of panels, by 1.9 times. Panel output assumes an 80% system performance ratio. Wind or solar runs the same comparison for every county.
How this is worked out
Wind is NASA's Power climate record, the 2001-2025 average at 10 m and 50 m for the county's centre, carried to 30 m with this county's own measured wind shear and spread into hours with a Rayleigh distribution. The turbine is a generic 10 kW, 7 m rotor machine with 10% losses. Cost is $10,000 per kW installed with no tax credit, because the federal one ended in 2025. One county-centre number cannot see your hilltop or your tree line, so treat it as the starting point for a site survey, not a substitute. The full method and its weak spots are in how the numbers are made.