Wind Turbine Payback in Hamblen County, TN
Wind turbine payback in Hamblen 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 Hamblen County, TN averages 3.3 m/s (7.4 mph). A 10 kW turbine there would make about 3,577 kWh a year, worth $494 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 Hamblen County
A home turbine is not worth buying for savings in Hamblen County unless your spot is far windier than the county average, 8.4 m/s at the hub against 3.3 m/s here. Per kW, solar panels would make about 1,232 kWh a year here against the turbine's 358, so get a solar quote first.
What would have to change
- Power would have to cost 140¢/kWh, 10.1 times what TN pays now.
- Or the average wind at the hub would have to be 8.4 m/s instead of 3.3. A taller tower or an exposed ridge can add some of that; a rooftop never will.
Against the rest of TN
Hamblen County is the 2,741st 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 Hamblen County
March is the strongest month here, at 3.98 m/s and about 548 kWh. August is the weakest, 2.39 m/s and 96 kWh, so the best month makes 5.7 times the worst. November to March brings in 60% of the year's output in Hamblen County.
| Month | Wind at 30 m | Output | Worth |
|---|---|---|---|
| January | 3.88 m/s | 511 kWh | $71 |
| February | 4.04 m/s | 521 kWh | $72 |
| March | 3.98 m/s | 548 kWh | $76 |
| April | 3.93 m/s | 510 kWh | $70 |
| May | 3.24 m/s | 286 kWh | $39 |
| June | 2.74 m/s | 157 kWh | $22 |
| July | 2.54 m/s | 121 kWh | $17 |
| August | 2.39 m/s | 96 kWh | $13 |
| September | 2.69 m/s | 145 kWh | $20 |
| October | 3.17 m/s | 265 kWh | $37 |
| November | 3.41 m/s | 328 kWh | $45 |
| December | 3.64 m/s | 415 kWh | $57 |
What a taller tower would buy
Measured at 10 m the wind in Hamblen County averages 2.19 m/s; at 50 m it is 3.99 m/s. That gives a shear exponent of 0.373, typical of rough, sheltered ground: trees or buildings slow the low wind a lot. Going from 20 m to 50 m takes output from 2,138 to 6,527 kWh a year, 205% 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 | 2.83 m/s | 2,138 kWh | over 100 years |
| 30 m | 3.3 m/s | 3,569 kWh | over 100 years |
| 40 m | 3.67 m/s | 5,040 kWh | over 100 years |
| 50 m | 3.99 m/s | 6,527 kWh | over 100 years |
Counties around Hamblen County
1 of the 6 closest counties is windier at turbine height; the windiest, Jefferson County, averages 3.36 m/s.
- Grainger County, TN: 3.14 m/s, 3,034 kWh, payback over 100 years (14 mi)
- Jefferson County, TN: 3.36 m/s, 3,794 kWh, payback over 100 years (15 mi)
- Hancock County, TN: 3.18 m/s, 3,165 kWh, payback over 100 years (21 mi)
- Cocke County, TN: 3.3 m/s, 3,577 kWh, payback over 100 years (22 mi)
- Greene County, TN: 3.3 m/s, 3,577 kWh, payback over 100 years (23 mi)
- Hawkins County, TN: 3.18 m/s, 3,165 kWh, payback over 100 years (25 mi)
Sun versus wind in Hamblen County
Hamblen County gets 4.22 kWh of sunshine per square metre a day on average. One kW of solar panels here would make roughly 1,232 kWh a year; one kW of the turbine above makes 358. Kilowatt for kilowatt, panels make 3.4 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.