Wind Turbine Payback in Jasper County, IA
Wind turbine payback in Jasper 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 Jasper 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 Jasper County
A home turbine is not worth buying for savings in Jasper 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 1,194 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
Jasper 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 Jasper County
April is the strongest month here, at 6.97 m/s and about 2,206 kWh. August is the weakest, 4.82 m/s and 963 kWh, so the best month makes 2.3 times the worst. November to March brings in 48% of the year's output in Jasper County.
| Month | Wind at 30 m | Output | Worth |
|---|---|---|---|
| January | 6.46 m/s | 1,966 kWh | $286 |
| February | 6.47 m/s | 1,780 kWh | $259 |
| March | 6.70 m/s | 2,110 kWh | $307 |
| April | 6.97 m/s | 2,206 kWh | $321 |
| May | 6.23 m/s | 1,820 kWh | $265 |
| June | 5.51 m/s | 1,326 kWh | $193 |
| July | 4.85 m/s | 978 kWh | $142 |
| August | 4.82 m/s | 963 kWh | $140 |
| September | 5.71 m/s | 1,443 kWh | $210 |
| October | 6.35 m/s | 1,893 kWh | $275 |
| November | 6.56 m/s | 1,961 kWh | $285 |
| December | 6.29 m/s | 1,854 kWh | $270 |
What a taller tower would buy
Measured at 10 m the wind in Jasper County averages 4.72 m/s; at 50 m it is 6.83 m/s. That gives a shear exponent of 0.230, typical of ordinary open country. Going from 20 m to 50 m takes output from 16,269 to 25,819 kWh a year, 59% 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 | 16,269 kWh | 42 years |
| 30 m | 6.07 m/s | 20,244 kWh | 34 years |
| 40 m | 6.49 m/s | 23,321 kWh | 30 years |
| 50 m | 6.83 m/s | 25,819 kWh | 27 years |
Counties around Jasper County
3 of the 6 closest counties are windier at turbine height; the windiest, Story County, averages 6.21 m/s.
- Marion County, IA: 6.07 m/s, 20,223 kWh, payback 34 years (25 mi)
- Marshall County, IA: 6.2 m/s, 21,187 kWh, payback 32 years (25 mi)
- Polk County, IA: 6.14 m/s, 20,742 kWh, payback 33 years (27 mi)
- Poweshiek County, IA: 6.07 m/s, 20,223 kWh, payback 34 years (27 mi)
- Story County, IA: 6.21 m/s, 21,262 kWh, payback 32 years (32 mi)
- Mahaska County, IA: 6.07 m/s, 20,223 kWh, payback 34 years (33 mi)
Sun versus wind in Jasper County
Jasper County gets 4.09 kWh of sunshine per square metre a day on average. One kW of solar panels here would make roughly 1,194 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.