Wind Turbine Payback in Limestone County, AL
Wind turbine payback in Limestone 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 Limestone County, AL averages 3.99 m/s (8.9 mph). A 10 kW turbine there would make about 6,527 kWh a year, worth $1,078 at AL's 16.51¢/kWh. Against an installed cost of about $100,000, that is a payback of 93 years, and the turbine is built to last about 20.
What to do in Limestone County
A home turbine is not worth buying for savings in Limestone County unless your spot is far windier than the county average, 7.5 m/s at the hub against 3.99 m/s here. Per kW, solar panels would make about 1,294 kWh a year here against the turbine's 653, so get a solar quote first.
What would have to change
- Power would have to cost 77¢/kWh, 4.6 times what AL pays now.
- Or the average wind at the hub would have to be 7.5 m/s instead of 3.99. A taller tower or an exposed ridge can add some of that; a rooftop never will.
Against the rest of AL
Limestone County is the 2,064th windiest of 3,144 US counties at turbine height; the national middle is 4.79 m/s. The windiest in AL is Mobile County at 4.72 m/s, payback 57 years.
Month by month in Limestone County
March is the strongest month here, at 4.76 m/s and about 930 kWh. July is the weakest, 2.88 m/s and 191 kWh, so the best month makes 4.9 times the worst. November to March brings in 58% of the year's output in Limestone County.
| Month | Wind at 30 m | Output | Worth |
|---|---|---|---|
| January | 4.62 m/s | 854 kWh | $141 |
| February | 4.79 m/s | 853 kWh | $141 |
| March | 4.76 m/s | 930 kWh | $154 |
| April | 4.69 m/s | 865 kWh | $143 |
| May | 3.86 m/s | 499 kWh | $82 |
| June | 3.22 m/s | 270 kWh | $45 |
| July | 2.88 m/s | 191 kWh | $32 |
| August | 2.97 m/s | 214 kWh | $35 |
| September | 3.46 m/s | 343 kWh | $57 |
| October | 3.93 m/s | 530 kWh | $88 |
| November | 4.30 m/s | 674 kWh | $111 |
| December | 4.43 m/s | 758 kWh | $125 |
What a taller tower would buy
Measured at 10 m the wind in Limestone County averages 2.77 m/s; at 50 m it is 4.73 m/s. That gives a shear exponent of 0.332, typical of rough, sheltered ground: trees or buildings slow the low wind a lot. Going from 20 m to 50 m takes output from 4,286 to 10,762 kWh a year, 151% 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 | 3.49 m/s | 4,286 kWh | over 100 years |
| 30 m | 3.99 m/s | 6,538 kWh | 93 years |
| 40 m | 4.39 m/s | 8,703 kWh | 70 years |
| 50 m | 4.73 m/s | 10,762 kWh | 56 years |
Counties around Limestone County
1 of the 6 closest counties is windier at turbine height; the windiest, Lawrence County, averages 4.02 m/s.
- Madison County, AL: 3.8 m/s, 5,614 kWh, payback over 100 years (25 mi)
- Morgan County, AL: 3.84 m/s, 5,800 kWh, payback over 100 years (26 mi)
- Giles County, TN: 3.99 m/s, 6,527 kWh, payback over 100 years (27 mi)
- Lawrence County, AL: 3.87 m/s, 5,942 kWh, payback over 100 years (27 mi)
- Lincoln County, TN: 3.99 m/s, 6,527 kWh, payback over 100 years (32 mi)
- Lawrence County, TN: 4.02 m/s, 6,678 kWh, payback over 100 years (37 mi)
Sun versus wind in Limestone County
Limestone County gets 4.43 kWh of sunshine per square metre a day on average. One kW of solar panels here would make roughly 1,294 kWh a year; one kW of the turbine above makes 653. Kilowatt for kilowatt, panels make 2.0 times as much here as the turbine. 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.