Wind Turbine Payback in Lewis and Clark County, MT
Wind turbine payback in Lewis and Clark 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 Lewis and Clark County, MT averages 3.93 m/s (8.8 mph). A 10 kW turbine there would make about 6,231 kWh a year, worth $880 at MT's 14.13¢/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 Lewis and Clark County
A home turbine is not worth buying for savings in Lewis and Clark County unless your spot is far windier than the county average, 8.2 m/s at the hub against 3.93 m/s here. Per kW, solar panels would make about 1,133 kWh a year here against the turbine's 623, so get a solar quote first.
What would have to change
- Power would have to cost 80¢/kWh, 5.7 times what MT pays now.
- Or the average wind at the hub would have to be 8.2 m/s instead of 3.93. A taller tower or an exposed ridge can add some of that; a rooftop never will.
Against the rest of MT
Lewis and Clark County is the 2,112th 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 Lewis and Clark County
January is the strongest month here, at 4.62 m/s and about 856 kWh. August is the weakest, 3.13 m/s and 254 kWh, so the best month makes 3.4 times the worst. November to March brings in 57% of the year's output in Lewis and Clark County.
| Month | Wind at 30 m | Output | Worth |
|---|---|---|---|
| January | 4.62 m/s | 856 kWh | $121 |
| February | 4.25 m/s | 608 kWh | $86 |
| March | 4.31 m/s | 700 kWh | $99 |
| April | 3.97 m/s | 529 kWh | $75 |
| May | 3.55 m/s | 383 kWh | $54 |
| June | 3.49 m/s | 351 kWh | $50 |
| July | 3.24 m/s | 285 kWh | $40 |
| August | 3.13 m/s | 254 kWh | $36 |
| September | 3.48 m/s | 349 kWh | $49 |
| October | 4.10 m/s | 604 kWh | $85 |
| November | 4.52 m/s | 778 kWh | $110 |
| December | 4.48 m/s | 783 kWh | $111 |
What a taller tower would buy
Measured at 10 m the wind in Lewis and Clark County averages 2.66 m/s; at 50 m it is 4.71 m/s. That gives a shear exponent of 0.355, typical of rough, sheltered ground: trees or buildings slow the low wind a lot. Going from 20 m to 50 m takes output from 3,950 to 10,635 kWh a year, 169% 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 | 3.4 m/s | 3,950 kWh | over 100 years |
| 30 m | 3.93 m/s | 6,225 kWh | over 100 years |
| 40 m | 4.35 m/s | 8,467 kWh | 84 years |
| 50 m | 4.71 m/s | 10,635 kWh | 67 years |
Counties around Lewis and Clark County
4 of the 6 closest counties are windier at turbine height; the windiest, Cascade County, averages 5.69 m/s.
- Powell County, MT: 3.35 m/s, 3,757 kWh, payback over 100 years (32 mi)
- Teton County, MT: 5.4 m/s, 15,319 kWh, payback 46 years (48 mi)
- Cascade County, MT: 5.69 m/s, 17,419 kWh, payback 41 years (50 mi)
- Broadwater County, MT: 3.97 m/s, 6,428 kWh, payback over 100 years (69 mi)
- Granite County, MT: 3.77 m/s, 5,477 kWh, payback over 100 years (70 mi)
- Jefferson County, MT: 4.03 m/s, 6,729 kWh, payback over 100 years (71 mi)
Sun versus wind in Lewis and Clark County
Lewis and Clark County gets 3.88 kWh of sunshine per square metre a day on average. One kW of solar panels here would make roughly 1,133 kWh a year; one kW of the turbine above makes 623. Kilowatt for kilowatt, panels make 1.8 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.