FOWLER, Ind.—BP PLC does big business harvesting energy in and around this farm town. But it isn’t oil and gas—it’s wind.

Hundreds of wind turbines ring Fowler, their white towers rising for miles amid the golden-tipped cornfields and leafy soybean plants blanketing much of Benton County, pop. 8,650. More than half of the county’s 560 turbines are operated by BP, which has three wind farms here.

“Turbines...