Compared to traditional energy sources (coal, oil, natural gas), wind energy seems like an environmentalist’s dream come true: It doesn’t pollute the air, land, or water, and it’s infinitely renewable. Indeed, wind energy has a reputation as being one of the greenest energy sources out there. So why are environmentalists trying to put a stop to the construction of 47 giant windmills in Pennsylvania’s Moosic Mountain Ridge? First, because wind farms take up a lot of space and often are located in otherwise unspoiled natural areas, and second, because the wind turbines themselves have a reputation for being avian Cuisinarts. The environmental organization R.E.S.C.U.E. is challenging the state-issued permit for the wind farms, and Sierra Club members are urging caution about the project. But other environmentalists think the resistance is just an example of “Not In My Backyard” thinking, and support the clean energy source. Such tension could become more common in Pennsylvania and other mid-Atlantic states, which used to be seen as insufficiently windy for wind farms. As windmill technology improves, however, and as people become more concerned about air quality, wind power is making inroads into new territory.