Harding Street Station

The Harding Street Station (formerly Elmer W. Stout Generating Station ) is a 12-unit, 1,196 MW nameplate capacity, gas-, coal, and oil-fired generating station located at 3700 S. Harding St., in Indianapolis, Indiana, U.S. It is owned by AES Indiana, a subsidiary of AES (formerly known as Indianapolis Power & Light). Completed in 1973, Harding Street Station's tallest chimneys are 565 ft in height.

Sulphur dioxide
With its oldest coal-fired unit dating back to 1958, the plant was ranked 12th on the United States list of dirtiest power plants in terms of sulphur dioxide emissions per megawatt-hour of electrical energy produced from coal in 2005.

The new flue gas desulphurization system (FGS), also known as a scrubber, and the new stack are expected to reduce sulfur dioxide (SO2) emissions by 97 percent, and NOx emissions, as well as other pollutants, by some 87 percent.

IPL stopped burning coal at the Harding Street facility in 2016 and retrofitted the units to natural gas.

Coal ash ponds
On the south side of the former plant is a sequence of unlined coal ash ponds. As of 2019, there were 27 groundwater monitoring wells. Between 2016 and 2019, 24 of these were polluted above federal advisory levels of molybdenum, boron, lithium, sulfate, arsenic, antimony, selenium, and cobalt.