Wind Turbine Payback in Bennett County, SD
Wind turbine payback in Bennett 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 Bennett County, SD averages 6.73 m/s (15.1 mph). A 10 kW turbine there would make about 25,093 kWh a year, worth $3,659 at SD's 14.58¢/kWh. Against an installed cost of about $100,000, that is a payback of 27 years, and the turbine is built to last about 20.
What to do in Bennett County
A home turbine is not worth buying for savings in Bennett County unless your spot is far windier than the county average, 8.1 m/s at the hub against 6.73 m/s here. Per kW, solar panels would make about 1,261 kWh a year here against the turbine's 2,509, so get a solar quote first.
What would have to change
- Power would have to cost 20¢/kWh, 1.4 times what SD pays now.
- Or the average wind at the hub would have to be 8.1 m/s instead of 6.73. A taller tower or an exposed ridge can add some of that; a rooftop never will.
Against the rest of SD
Bennett County is the 46th windiest of 3,144 US counties at turbine height; the national middle is 4.79 m/s. The windiest in SD is Todd County at 6.77 m/s, payback 27 years.
Month by month in Bennett County
January is the strongest month here, at 7.40 m/s and about 2,536 kWh. July is the weakest, 5.75 m/s and 1,514 kWh, so the best month makes 1.7 times the worst. November to March brings in 47% of the year's output in Bennett County.
| Month | Wind at 30 m | Output | Worth |
|---|---|---|---|
| January | 7.40 m/s | 2,536 kWh | $370 |
| February | 7.00 m/s | 2,072 kWh | $302 |
| March | 7.01 m/s | 2,305 kWh | $336 |
| April | 7.09 m/s | 2,273 kWh | $331 |
| May | 6.57 m/s | 2,034 kWh | $297 |
| June | 6.12 m/s | 1,695 kWh | $247 |
| July | 5.75 m/s | 1,514 kWh | $221 |
| August | 5.87 m/s | 1,593 kWh | $232 |
| September | 6.46 m/s | 1,897 kWh | $277 |
| October | 6.98 m/s | 2,283 kWh | $333 |
| November | 7.22 m/s | 2,351 kWh | $343 |
| December | 7.31 m/s | 2,483 kWh | $362 |
What a taller tower would buy
Measured at 10 m the wind in Bennett County averages 5.35 m/s; at 50 m it is 7.48 m/s. That gives a shear exponent of 0.208, typical of ordinary open country. Going from 20 m to 50 m takes output from 21,054 to 30,400 kWh a year, 44% 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 | 6.18 m/s | 21,054 kWh | 33 years |
| 30 m | 6.73 m/s | 25,064 kWh | 27 years |
| 40 m | 7.14 m/s | 28,043 kWh | 25 years |
| 50 m | 7.48 m/s | 30,400 kWh | 23 years |
Counties around Bennett County
2 of the 6 closest counties are windier at turbine height; the windiest, Cherry County, averages 6.83 m/s.
- Jackson County, SD: 6.49 m/s, 23,333 kWh, payback 29 years (34 mi)
- Oglala Lakota County, SD: 5.99 m/s, 19,630 kWh, payback 35 years (46 mi)
- Todd County, SD: 6.77 m/s, 25,384 kWh, payback 27 years (49 mi)
- Cherry County, NE: 6.83 m/s, 25,819 kWh, payback 30 years (53 mi)
- Mellette County, SD: 6.55 m/s, 23,775 kWh, payback 29 years (54 mi)
- Sheridan County, NE: 6.61 m/s, 24,216 kWh, payback 32 years (58 mi)
Sun versus wind in Bennett County
Bennett County gets 4.32 kWh of sunshine per square metre a day on average. One kW of solar panels here would make roughly 1,261 kWh a year; one kW of the turbine above makes 2,509. This is one of the rare places where a kilowatt of turbine out-produces a kilowatt of panels, by 2.0 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.