Wind Turbine Payback in Garfield County, MT
Wind turbine payback in Garfield 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 Garfield County, MT averages 6.41 m/s (14.3 mph). A 10 kW turbine there would make about 22,743 kWh a year, worth $3,214 at MT's 14.13¢/kWh. Against an installed cost of about $100,000, that is a payback of 31 years, and the turbine is built to last about 20.
What to do in Garfield County
A home turbine is not worth buying for savings in Garfield County unless your spot is far windier than the county average, 8.2 m/s at the hub against 6.41 m/s here. Per kW, solar panels would make about 1,168 kWh a year here against the turbine's 2,274, so get a solar quote first.
What would have to change
- Power would have to cost 22¢/kWh, 1.6 times what MT pays now.
- Or the average wind at the hub would have to be 8.2 m/s instead of 6.41. A taller tower or an exposed ridge can add some of that; a rooftop never will.
Against the rest of MT
Garfield County is the 309th windiest of 3,144 US counties at turbine height; the national middle is 4.79 m/s. The windiest in MT is Fallon County at 6.64 m/s, payback 29 years.
Month by month in Garfield County
January is the strongest month here, at 7.07 m/s and about 2,341 kWh. July is the weakest, 5.60 m/s and 1,426 kWh, so the best month makes 1.6 times the worst. November to March brings in 46% of the year's output in Garfield County.
| Month | Wind at 30 m | Output | Worth |
|---|---|---|---|
| January | 7.07 m/s | 2,341 kWh | $331 |
| February | 6.27 m/s | 1,666 kWh | $235 |
| March | 6.55 m/s | 2,020 kWh | $285 |
| April | 6.54 m/s | 1,949 kWh | $275 |
| May | 6.36 m/s | 1,901 kWh | $269 |
| June | 6.03 m/s | 1,637 kWh | $231 |
| July | 5.60 m/s | 1,426 kWh | $201 |
| August | 5.68 m/s | 1,471 kWh | $208 |
| September | 6.06 m/s | 1,658 kWh | $234 |
| October | 6.78 m/s | 2,159 kWh | $305 |
| November | 7.07 m/s | 2,266 kWh | $320 |
| December | 6.83 m/s | 2,193 kWh | $310 |
What a taller tower would buy
Measured at 10 m the wind in Garfield County averages 5.12 m/s; at 50 m it is 7.11 m/s. That gives a shear exponent of 0.204, typical of ordinary open country. Going from 20 m to 50 m takes output from 18,948 to 27,826 kWh a year, 47% 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 | 5.9 m/s | 18,948 kWh | 37 years |
| 30 m | 6.41 m/s | 22,716 kWh | 31 years |
| 40 m | 6.79 m/s | 25,556 kWh | 28 years |
| 50 m | 7.11 m/s | 27,826 kWh | 25 years |
Counties around Garfield County
1 of the 6 closest counties is windier at turbine height; the windiest, McCone County, averages 6.43 m/s.
- Petroleum County, MT: 5.89 m/s, 18,890 kWh, payback 38 years (58 mi)
- McCone County, MT: 6.43 m/s, 22,891 kWh, payback 31 years (63 mi)
- Treasure County, MT: 5.74 m/s, 17,785 kWh, payback 40 years (73 mi)
- Valley County, MT: 6.11 m/s, 20,520 kWh, payback 35 years (76 mi)
- Prairie County, MT: 6.37 m/s, 22,447 kWh, payback 32 years (77 mi)
- Rosebud County, MT: 5.92 m/s, 19,112 kWh, payback 37 years (77 mi)
Sun versus wind in Garfield County
Garfield County gets 4 kWh of sunshine per square metre a day on average. One kW of solar panels here would make roughly 1,168 kWh a year; one kW of the turbine above makes 2,274. 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.