Indianapolis Power & Light's Harding Street station.
The south-side plant along the banks of the White River went online in 1931. - Photos by Eric Learned
In November, the plant converted its two smaller turbines, which each generate about 105 megawatts, to natural gas. - Photos by Eric Learned
The control room features a mixture of modern computer gear and equipment dating back decades. - Photos by Eric Learned
The last active coal unit will go offline for about eight weeks, for its natural-gas conversion. - Photos by Eric Learned
The Indiana coal industry employs more than 26,000 people. - Photos by Eric Learned
In 2010, Indiana had 26 active coal-burning power plants. By the end of this year, the state will have just 13. - Photos by Eric Learned
The coal piles are nearly depleted