The massive coal-burning Sammis Power Plant on the Ohio River north of Steubenville uses scrubbers to clear pollutants from the smoke it sends up its giant stacks. The phosphorus control idea starts with a by-product of those scrubbers.
Warren Dick is a professor of soil and environmental chemistry at the Ohio Agricultural Research & Development Center: “When you burn coal you produce sulfur dioxide gasses, and the Clean Air Act has required the removal of that because of acid rain, and they make this by product called gypsum, calcium sulfate.”
Gypsum is used for a number of things, including wall board. But, it turns out it also solves an environmental problem; it prevents phosphorous in farm fertilizers from getting into streams and lakes. That’s a problem thought to have been brought under control in the 1980s. “A lot of phosphorus that was getting into our lakes was piggybacking on sediment…erosion. So they really pushed hard on conservation practices, tillage, and no tillage. It cut down the sediment phosphorous loading into Lake Erie. Then about 1990, they started to see this other thing going up, and that is soluble phosphorous loading.”
Phosphorus loading occurs when an unusual amount of the chemical accumulates in a body of water. Changes in how and when fertilizer is applied have made it easier for rain to dissolve phosphates and wash them out of the fields and into streams and lakes.
Kent State University oceanography professor Joseph Ortiz uses satellite images and other technologies to track the effects of that phosphate flow. He and his team monitor algae growth in Lake Erie, Grand Lake St. Mary’s and other state parks — where huge algae blooms have posed threats to health. Ortiz explains phosphorous spurs algae growth once it gets to lakes because tiny plants eat it. “When you put that additional nutrient in the lake, the microscopic plants suddenly had access to tremendous amounts of food, and they went to town with it.”
But, Dick’s Ohio State research team is getting positive results in tests spreading powdered gypsum from the smoke scrubbers on farm fields to head off phosphate migration. Gypsum forms bonds with the phosphorous in the fertilizer in a way that makes it less soluble in water, and therefore more likely to stay put on the crops it is intended to nourish.
The gypsum from smoke scrubbers that is at the root of all the research is entirely from First Energy’s Sammis plant, where nearly half a million tons of it was produced last year. That will drop off in the future, however, because the company has scaled Sammis back to “as needed” operations as part of its strategy to reduce the use of coal in power generation.