Wind Turbine Payback in Liberty County, MT
Wind turbine payback in Liberty 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 Liberty County, MT averages 6.21 m/s (13.9 mph). A 10 kW turbine there would make about 21,262 kWh a year, worth $3,004 at MT's 14.13¢/kWh. Against an installed cost of about $100,000, that is a payback of 33 years, and the turbine is built to last about 20.
What to do in Liberty County
A home turbine is not worth buying for savings in Liberty County unless your spot is far windier than the county average, 8.2 m/s at the hub against 6.21 m/s here. Per kW, solar panels would make about 1,142 kWh a year here against the turbine's 2,126, so get a solar quote first.
What would have to change
- Power would have to cost 24¢/kWh, 1.7 times what MT pays now.
- Or the average wind at the hub would have to be 8.2 m/s instead of 6.21. A taller tower or an exposed ridge can add some of that; a rooftop never will.
Against the rest of MT
Liberty County is the 576th 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 Liberty County
January is the strongest month here, at 7.08 m/s and about 2,343 kWh. August is the weakest, 5.05 m/s and 1,094 kWh, so the best month makes 2.1 times the worst. November to March brings in 50% of the year's output in Liberty County.
| Month | Wind at 30 m | Output | Worth |
|---|---|---|---|
| January | 7.08 m/s | 2,343 kWh | $331 |
| February | 6.41 m/s | 1,743 kWh | $246 |
| March | 6.60 m/s | 2,052 kWh | $290 |
| April | 6.36 m/s | 1,840 kWh | $260 |
| May | 5.95 m/s | 1,643 kWh | $232 |
| June | 5.81 m/s | 1,504 kWh | $213 |
| July | 5.35 m/s | 1,273 kWh | $180 |
| August | 5.05 m/s | 1,094 kWh | $155 |
| September | 5.57 m/s | 1,359 kWh | $192 |
| October | 6.55 m/s | 2,019 kWh | $285 |
| November | 7.00 m/s | 2,220 kWh | $314 |
| December | 6.79 m/s | 2,169 kWh | $306 |
What a taller tower would buy
Measured at 10 m the wind in Liberty County averages 4.86 m/s; at 50 m it is 6.96 m/s. That gives a shear exponent of 0.223, typical of ordinary open country. Going from 20 m to 50 m takes output from 17,300 to 26,756 kWh a year, 55% 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 | 5.67 m/s | 17,300 kWh | 41 years |
| 30 m | 6.21 m/s | 21,266 kWh | 33 years |
| 40 m | 6.62 m/s | 24,305 kWh | 29 years |
| 50 m | 6.96 m/s | 26,756 kWh | 27 years |
Counties around Liberty County
None of the 6 closest counties is windier than Liberty County.
- Toole County, MT: 6.17 m/s, 20,965 kWh, payback 34 years (32 mi)
- Hill County, MT: 6.21 m/s, 21,262 kWh, payback 33 years (43 mi)
- Chouteau County, MT: 6.09 m/s, 20,371 kWh, payback 35 years (54 mi)
- Pondera County, MT: 5.4 m/s, 15,319 kWh, payback 46 years (59 mi)
- Teton County, MT: 5.4 m/s, 15,319 kWh, payback 46 years (77 mi)
- Cascade County, MT: 5.69 m/s, 17,419 kWh, payback 41 years (87 mi)
Sun versus wind in Liberty County
Liberty County gets 3.91 kWh of sunshine per square metre a day on average. One kW of solar panels here would make roughly 1,142 kWh a year; one kW of the turbine above makes 2,126. 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.