Wind Turbine Payback in Poweshiek County, IA
Wind turbine payback in Poweshiek 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 Poweshiek County, IA averages 6.07 m/s (13.6 mph). A 10 kW turbine there would make about 20,223 kWh a year, worth $2,942 at IA's 14.55¢/kWh. Against an installed cost of about $100,000, that is a payback of 34 years, and the turbine is built to last about 20.
What to do in Poweshiek County
A home turbine is not worth buying for savings in Poweshiek County unless your spot is far windier than the county average, 8.1 m/s at the hub against 6.07 m/s here. Per kW, solar panels would make about 1,188 kWh a year here against the turbine's 2,022, so get a solar quote first.
What would have to change
- Power would have to cost 25¢/kWh, 1.7 times what IA pays now.
- Or the average wind at the hub would have to be 8.1 m/s instead of 6.07. A taller tower or an exposed ridge can add some of that; a rooftop never will.
Against the rest of IA
Poweshiek County is the 717th 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 Poweshiek County
April is the strongest month here, at 7.00 m/s and about 2,223 kWh. August is the weakest, 4.79 m/s and 949 kWh, so the best month makes 2.3 times the worst. November to March brings in 48% of the year's output in Poweshiek County.
| Month | Wind at 30 m | Output | Worth |
|---|---|---|---|
| January | 6.50 m/s | 1,990 kWh | $290 |
| February | 6.50 m/s | 1,797 kWh | $261 |
| March | 6.71 m/s | 2,117 kWh | $308 |
| April | 7.00 m/s | 2,223 kWh | $323 |
| May | 6.21 m/s | 1,805 kWh | $263 |
| June | 5.47 m/s | 1,301 kWh | $189 |
| July | 4.80 m/s | 954 kWh | $139 |
| August | 4.79 m/s | 949 kWh | $138 |
| September | 5.66 m/s | 1,412 kWh | $205 |
| October | 6.37 m/s | 1,906 kWh | $277 |
| November | 6.57 m/s | 1,969 kWh | $286 |
| December | 6.31 m/s | 1,867 kWh | $272 |
What a taller tower would buy
Measured at 10 m the wind in Poweshiek County averages 4.72 m/s; at 50 m it is 6.82 m/s. That gives a shear exponent of 0.229, typical of ordinary open country. Going from 20 m to 50 m takes output from 16,247 to 25,747 kWh a year, 58% 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 | 5.53 m/s | 16,247 kWh | 42 years |
| 30 m | 6.07 m/s | 20,201 kWh | 34 years |
| 40 m | 6.48 m/s | 23,261 kWh | 30 years |
| 50 m | 6.82 m/s | 25,747 kWh | 27 years |
Counties around Poweshiek County
2 of the 6 closest counties are windier at turbine height; the windiest, Marshall County, averages 6.2 m/s.
- Iowa County, IA: 6.03 m/s, 19,926 kWh, payback 35 years (24 mi)
- Mahaska County, IA: 6.07 m/s, 20,223 kWh, payback 34 years (25 mi)
- Tama County, IA: 6.18 m/s, 21,039 kWh, payback 33 years (27 mi)
- Jasper County, IA: 6.07 m/s, 20,223 kWh, payback 34 years (27 mi)
- Keokuk County, IA: 6.03 m/s, 19,926 kWh, payback 35 years (31 mi)
- Marshall County, IA: 6.2 m/s, 21,187 kWh, payback 32 years (34 mi)
Sun versus wind in Poweshiek County
Poweshiek County gets 4.07 kWh of sunshine per square metre a day on average. One kW of solar panels here would make roughly 1,188 kWh a year; one kW of the turbine above makes 2,022. This is one of the rare places where a kilowatt of turbine out-produces a kilowatt of panels, by 1.7 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.