In the last half-century, the GE Gas Power plant in Greenville, South Carolina, has experienced the same kind of dizzying roller coaster ride as the city where it’s located. Founded some 200 years ago on the Reedy River, Greenville grew into a textile manufacturing hot spot and a paragon of Southern hospitality — until the 1970s, when the city’s downtown took a turn. Mills closed, hotels shuttered, and the clattering trams carrying riders on shopping errands and to business lunches fell silent.