Wind Turbine Payback in Lewis County, WA
Wind turbine payback in Lewis 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 County, WA averages 2.94 m/s (6.6 mph). A 10 kW turbine there would make about 2,427 kWh a year, worth $350 at WA's 14.42¢/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 County
A home turbine is not worth buying for savings in Lewis County unless your spot is far windier than the county average, 8.1 m/s at the hub against 2.94 m/s here. Per kW, solar panels would make about 1,013 kWh a year here against the turbine's 243, so get a solar quote first.
What would have to change
- Power would have to cost 206¢/kWh, 14.3 times what WA pays now.
- Or the average wind at the hub would have to be 8.1 m/s instead of 2.94. A taller tower or an exposed ridge can add some of that; a rooftop never will.
Against the rest of WA
Lewis County is the 3,095th windiest of 3,144 US counties at turbine height; the national middle is 4.79 m/s. The windiest in WA is Columbia County at 5.18 m/s, payback 50 years.
Month by month in Lewis County
January is the strongest month here, at 3.69 m/s and about 435 kWh. July is the weakest, 2.30 m/s and 83 kWh, so the best month makes 5.2 times the worst. November to March brings in 66% of the year's output in Lewis County.
| Month | Wind at 30 m | Output | Worth |
|---|---|---|---|
| January | 3.69 m/s | 435 kWh | $63 |
| February | 3.31 m/s | 276 kWh | $40 |
| March | 3.19 m/s | 272 kWh | $39 |
| April | 2.81 m/s | 170 kWh | $25 |
| May | 2.46 m/s | 107 kWh | $15 |
| June | 2.38 m/s | 92 kWh | $13 |
| July | 2.30 m/s | 83 kWh | $12 |
| August | 2.35 m/s | 90 kWh | $13 |
| September | 2.59 m/s | 126 kWh | $18 |
| October | 3.03 m/s | 228 kWh | $33 |
| November | 3.54 m/s | 367 kWh | $53 |
| December | 3.63 m/s | 411 kWh | $59 |
What a taller tower would buy
Measured at 10 m the wind in Lewis County averages 1.9 m/s; at 50 m it is 3.6 m/s. That gives a shear exponent of 0.397, typical of rough, sheltered ground: trees or buildings slow the low wind a lot. Going from 20 m to 50 m takes output from 1,355 to 4,736 kWh a year, 250% 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 | 2.5 m/s | 1,355 kWh | over 100 years |
| 30 m | 2.94 m/s | 2,425 kWh | over 100 years |
| 40 m | 3.29 m/s | 3,558 kWh | over 100 years |
| 50 m | 3.6 m/s | 4,736 kWh | over 100 years |
Counties around Lewis County
3 of the 6 closest counties are windier at turbine height; the windiest, Skamania County, averages 3.12 m/s.
- Cowlitz County, WA: 2.96 m/s, 2,484 kWh, payback over 100 years (30 mi)
- Thurston County, WA: 2.81 m/s, 2,073 kWh, payback over 100 years (33 mi)
- Pierce County, WA: 2.87 m/s, 2,232 kWh, payback over 100 years (34 mi)
- Skamania County, WA: 3.12 m/s, 2,970 kWh, payback over 100 years (43 mi)
- Wahkiakum County, WA: 2.89 m/s, 2,287 kWh, payback over 100 years (54 mi)
- Columbia County, OR: 3 m/s, 2,601 kWh, payback over 100 years (55 mi)
Sun versus wind in Lewis County
Lewis County gets 3.47 kWh of sunshine per square metre a day on average. One kW of solar panels here would make roughly 1,013 kWh a year; one kW of the turbine above makes 243. Kilowatt for kilowatt, panels make 4.2 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.