Wind Turbine Payback in Des Moines County, IA
Wind turbine payback in Des Moines 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 Des Moines County, IA averages 6 m/s (13.4 mph). A 10 kW turbine there would make about 19,704 kWh a year, worth $2,867 at IA's 14.55¢/kWh. Against an installed cost of about $100,000, that is a payback of 35 years, and the turbine is built to last about 20.
What to do in Des Moines County
A home turbine is not worth buying for savings in Des Moines County unless your spot is far windier than the county average, 8.1 m/s at the hub against 6 m/s here. Per kW, solar panels would make about 1,191 kWh a year here against the turbine's 1,970, 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. A taller tower or an exposed ridge can add some of that; a rooftop never will.
Against the rest of IA
Des Moines County is the 840th 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 Des Moines County
April is the strongest month here, at 6.94 m/s and about 2,189 kWh. August is the weakest, 4.68 m/s and 888 kWh, so the best month makes 2.5 times the worst. November to March brings in 49% of the year's output in Des Moines County.
| Month | Wind at 30 m | Output | Worth |
|---|---|---|---|
| January | 6.48 m/s | 1,975 kWh | $287 |
| February | 6.46 m/s | 1,774 kWh | $258 |
| March | 6.66 m/s | 2,086 kWh | $304 |
| April | 6.94 m/s | 2,189 kWh | $318 |
| May | 6.10 m/s | 1,735 kWh | $252 |
| June | 5.40 m/s | 1,261 kWh | $183 |
| July | 4.71 m/s | 902 kWh | $131 |
| August | 4.68 m/s | 888 kWh | $129 |
| September | 5.46 m/s | 1,292 kWh | $188 |
| October | 6.28 m/s | 1,852 kWh | $269 |
| November | 6.58 m/s | 1,971 kWh | $287 |
| December | 6.28 m/s | 1,852 kWh | $269 |
What a taller tower would buy
Measured at 10 m the wind in Des Moines County averages 4.67 m/s; at 50 m it is 6.74 m/s. That gives a shear exponent of 0.228, typical of ordinary open country. Going from 20 m to 50 m takes output from 15,816 to 25,166 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 | 5.47 m/s | 15,816 kWh | 44 years |
| 30 m | 6 m/s | 19,697 kWh | 35 years |
| 40 m | 6.41 m/s | 22,711 kWh | 30 years |
| 50 m | 6.74 m/s | 25,166 kWh | 27 years |
Counties around Des Moines County
2 of the 6 closest counties are windier at turbine height; the windiest, Warren County, averages 6.02 m/s.
- Henderson County, IL: 6 m/s, 19,704 kWh, payback 26 years (15 mi)
- Henry County, IA: 6 m/s, 19,704 kWh, payback 35 years (19 mi)
- Louisa County, IA: 6 m/s, 19,704 kWh, payback 35 years (21 mi)
- Lee County, IA: 5.96 m/s, 19,408 kWh, payback 35 years (24 mi)
- Warren County, IL: 6.02 m/s, 19,852 kWh, payback 26 years (30 mi)
- Mercer County, IL: 6.02 m/s, 19,852 kWh, payback 26 years (31 mi)
Sun versus wind in Des Moines County
Des Moines County gets 4.08 kWh of sunshine per square metre a day on average. One kW of solar panels here would make roughly 1,191 kWh a year; one kW of the turbine above makes 1,970. 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.