Coal mines always have been big business. Wind farms are getting to be. And when heavy-hitting companies such as North American Coal Corp., Minnesota Power and Florida Power and Light are eyeing an area of real estate, you bet it's consequential. The real estate isn't paltry; it's a lot of acreage in Oliver and Morton counties. Minnesota Power and FPL want to build separate wind farms. But the coal company says, "Wait a minute, we may want to mine where you guys are talking about putting up wind turbines. That won't work."