Warren McKenna’s Jeep SUV glides past stubbled farm fields, kicking up dust and fresh snow where only weeks ago a bumper crop of corn and soybeans filled the horizon. . . . “It’s real good,” answers Yoder. “We’ve got strong sun and wind today. I figure I’m making more than 20,000 watts out there.”The 20 kilowatts, which help form the backbone of the electric cooperative’s 216-square-mile distribution grid, are coming from Yoder’s farm-based energy systems. They include two 7.2 kW solar arrays mounted on the south-facing slope of a nearby field and a 10 kW wind turbine set atop a steel tower that may be the tallest structure around outside the Frytown grain elevator. . . .