Wind Turbine Payback in Brule County, SD
Wind turbine payback in Brule 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 Brule County, SD averages 6.45 m/s (14.4 mph). A 10 kW turbine there would make about 23,038 kWh a year, worth $3,359 at SD's 14.58¢/kWh. Against an installed cost of about $100,000, that is a payback of 30 years, and the turbine is built to last about 20.
What to do in Brule County
A home turbine is not worth buying for savings in Brule County unless your spot is far windier than the county average, 8.1 m/s at the hub against 6.45 m/s here. Per kW, solar panels would make about 1,235 kWh a year here against the turbine's 2,304, so get a solar quote first.
What would have to change
- Power would have to cost 22¢/kWh, 1.5 times what SD pays now.
- Or the average wind at the hub would have to be 8.1 m/s instead of 6.45. A taller tower or an exposed ridge can add some of that; a rooftop never will.
Against the rest of SD
Brule County is the 257th 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 Brule County
April is the strongest month here, at 6.93 m/s and about 2,182 kWh. July is the weakest, 5.63 m/s and 1,442 kWh, so the best month makes 1.5 times the worst. November to March brings in 44% of the year's output in Brule County.
| Month | Wind at 30 m | Output | Worth |
|---|---|---|---|
| January | 6.71 m/s | 2,117 kWh | $309 |
| February | 6.43 m/s | 1,755 kWh | $256 |
| March | 6.69 m/s | 2,106 kWh | $307 |
| April | 6.93 m/s | 2,182 kWh | $318 |
| May | 6.63 m/s | 2,067 kWh | $301 |
| June | 6.03 m/s | 1,640 kWh | $239 |
| July | 5.63 m/s | 1,442 kWh | $210 |
| August | 5.74 m/s | 1,509 kWh | $220 |
| September | 6.53 m/s | 1,940 kWh | $283 |
| October | 6.78 m/s | 2,161 kWh | $315 |
| November | 6.68 m/s | 2,032 kWh | $296 |
| December | 6.57 m/s | 2,033 kWh | $296 |
What a taller tower would buy
Measured at 10 m the wind in Brule County averages 5.11 m/s; at 50 m it is 7.18 m/s. That gives a shear exponent of 0.211, typical of ordinary open country. Going from 20 m to 50 m takes output from 19,095 to 28,320 kWh a year, 48% 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 | 5.92 m/s | 19,095 kWh | 36 years |
| 30 m | 6.45 m/s | 23,011 kWh | 30 years |
| 40 m | 6.85 m/s | 25,963 kWh | 26 years |
| 50 m | 7.18 m/s | 28,320 kWh | 24 years |
Counties around Brule County
1 of the 6 closest counties is windier at turbine height; the windiest, Gregory County, averages 6.65 m/s.
- Buffalo County, SD: 6.35 m/s, 22,299 kWh, payback 31 years (22 mi)
- Aurora County, SD: 6.41 m/s, 22,743 kWh, payback 30 years (26 mi)
- Jerauld County, SD: 6.38 m/s, 22,521 kWh, payback 31 years (33 mi)
- Gregory County, SD: 6.65 m/s, 24,509 kWh, payback 28 years (39 mi)
- Lyman County, SD: 6.35 m/s, 22,299 kWh, payback 31 years (39 mi)
- Douglas County, SD: 6.4 m/s, 22,669 kWh, payback 30 years (44 mi)
Sun versus wind in Brule County
Brule County gets 4.23 kWh of sunshine per square metre a day on average. One kW of solar panels here would make roughly 1,235 kWh a year; one kW of the turbine above makes 2,304. This is one of the rare places where a kilowatt of turbine out-produces a kilowatt of panels, by 1.9 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.