Wind Turbine Payback in Mills County, IA
Wind turbine payback in Mills 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 Mills County, IA averages 6.23 m/s (13.9 mph). A 10 kW turbine there would make about 21,410 kWh a year, worth $3,115 at IA's 14.55¢/kWh. Against an installed cost of about $100,000, that is a payback of 32 years, and the turbine is built to last about 20.
What to do in Mills County
A home turbine is not worth buying for savings in Mills County unless your spot is far windier than the county average, 8.1 m/s at the hub against 6.23 m/s here. Per kW, solar panels would make about 1,215 kWh a year here against the turbine's 2,141, so get a solar quote first.
What would have to change
- Power would have to cost 23¢/kWh, 1.6 times what IA pays now.
- Or the average wind at the hub would have to be 8.1 m/s instead of 6.23. A taller tower or an exposed ridge can add some of that; a rooftop never will.
Against the rest of IA
Mills County is the 550th 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 Mills County
April is the strongest month here, at 7.16 m/s and about 2,316 kWh. August is the weakest, 5.03 m/s and 1,080 kWh, so the best month makes 2.1 times the worst. November to March brings in 46% of the year's output in Mills County.
| Month | Wind at 30 m | Output | Worth |
|---|---|---|---|
| January | 6.45 m/s | 1,960 kWh | $285 |
| February | 6.49 m/s | 1,790 kWh | $260 |
| March | 6.81 m/s | 2,182 kWh | $317 |
| April | 7.16 m/s | 2,316 kWh | $337 |
| May | 6.43 m/s | 1,943 kWh | $283 |
| June | 5.83 m/s | 1,516 kWh | $221 |
| July | 5.05 m/s | 1,095 kWh | $159 |
| August | 5.03 m/s | 1,080 kWh | $157 |
| September | 6.04 m/s | 1,641 kWh | $239 |
| October | 6.51 m/s | 1,993 kWh | $290 |
| November | 6.64 m/s | 2,010 kWh | $292 |
| December | 6.33 m/s | 1,881 kWh | $274 |
What a taller tower would buy
Measured at 10 m the wind in Mills County averages 4.88 m/s; at 50 m it is 6.98 m/s. That gives a shear exponent of 0.222, typical of ordinary open country. Going from 20 m to 50 m takes output from 17,457 to 26,900 kWh a year, 54% 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 | 5.7 m/s | 17,457 kWh | 39 years |
| 30 m | 6.23 m/s | 21,422 kWh | 32 years |
| 40 m | 6.64 m/s | 24,455 kWh | 28 years |
| 50 m | 6.98 m/s | 26,900 kWh | 26 years |
Counties around Mills County
3 of the 6 closest counties are windier at turbine height; the windiest, Pottawattamie County, averages 6.31 m/s.
- Fremont County, IA: 6.17 m/s, 20,965 kWh, payback 33 years (20 mi)
- Pottawattamie County, IA: 6.31 m/s, 22,003 kWh, payback 31 years (22 mi)
- Montgomery County, IA: 6.22 m/s, 21,336 kWh, payback 32 years (24 mi)
- Sarpy County, NE: 6.29 m/s, 21,855 kWh, payback 35 years (26 mi)
- Cass County, NE: 6.29 m/s, 21,855 kWh, payback 35 years (29 mi)
- Page County, IA: 6.1 m/s, 20,446 kWh, payback 34 years (32 mi)
Sun versus wind in Mills County
Mills County gets 4.16 kWh of sunshine per square metre a day on average. One kW of solar panels here would make roughly 1,215 kWh a year; one kW of the turbine above makes 2,141. This is one of the rare places where a kilowatt of turbine out-produces a kilowatt of panels, by 1.8 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.