Wind Turbine Payback in Stewart County, TN
Wind turbine payback in Stewart 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 Stewart County, TN averages 3.99 m/s (8.9 mph). A 10 kW turbine there would make about 6,527 kWh a year, worth $901 at TN's 13.8¢/kWh. Against an installed cost of about $100,000, that is a payback of over 100 years, and the turbine is built to last about 20.
What to do in Stewart County
A home turbine is not worth buying for savings in Stewart County unless your spot is far windier than the county average, 8.4 m/s at the hub against 3.99 m/s here. Per kW, solar panels would make about 1,241 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, 5.6 times what TN pays now.
- Or the average wind at the hub would have to be 8.4 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 TN
Stewart 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 TN is Lake County at 5.54 m/s, payback 44 years.
Month by month in Stewart County
March is the strongest month here, at 4.73 m/s and about 913 kWh. July is the weakest, 2.96 m/s and 211 kWh, so the best month makes 4.3 times the worst. November to March brings in 57% of the year's output in Stewart County.
| Month | Wind at 30 m | Output | Worth |
|---|---|---|---|
| January | 4.61 m/s | 850 kWh | $117 |
| February | 4.69 m/s | 804 kWh | $111 |
| March | 4.73 m/s | 913 kWh | $126 |
| April | 4.72 m/s | 879 kWh | $121 |
| May | 3.87 m/s | 504 kWh | $70 |
| June | 3.27 m/s | 285 kWh | $39 |
| July | 2.96 m/s | 211 kWh | $29 |
| August | 3.03 m/s | 228 kWh | $31 |
| September | 3.43 m/s | 335 kWh | $46 |
| October | 3.96 m/s | 542 kWh | $75 |
| November | 4.29 m/s | 665 kWh | $92 |
| December | 4.39 m/s | 740 kWh | $102 |
What a taller tower would buy
Measured at 10 m the wind in Stewart County averages 2.7 m/s; at 50 m it is 4.79 m/s. That gives a shear exponent of 0.356, typical of rough, sheltered ground: trees or buildings slow the low wind a lot. Going from 20 m to 50 m takes output from 4,159 to 11,147 kWh a year, 168% 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 | 3.46 m/s | 4,159 kWh | over 100 years |
| 30 m | 3.99 m/s | 6,545 kWh | over 100 years |
| 40 m | 4.42 m/s | 8,890 kWh | 82 years |
| 50 m | 4.79 m/s | 11,147 kWh | 65 years |
Counties around Stewart County
3 of the 6 closest counties are windier at turbine height; the windiest, Trigg County, averages 4.94 m/s.
- Houston County, TN: 3.99 m/s, 6,527 kWh, payback over 100 years (13 mi)
- Montgomery County, TN: 3.99 m/s, 6,527 kWh, payback over 100 years (24 mi)
- Trigg County, KY: 4.94 m/s, 12,132 kWh, payback 58 years (24 mi)
- Calloway County, KY: 4.17 m/s, 7,461 kWh, payback 94 years (28 mi)
- Henry County, TN: 4.17 m/s, 7,461 kWh, payback 97 years (29 mi)
- Humphreys County, TN: 3.51 m/s, 4,368 kWh, payback over 100 years (29 mi)
Sun versus wind in Stewart County
Stewart County gets 4.25 kWh of sunshine per square metre a day on average. One kW of solar panels here would make roughly 1,241 kWh a year; one kW of the turbine above makes 653. Kilowatt for kilowatt, panels make 1.9 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.