Gypsum from Power Plants: An Antidote to Algal Blooms
As a plentiful power plant by-product, flue gas desulfurization gypsum offers great potential to improve water quality and protect aquatic ecosystems by reducing phosphorus runoff from fertilized fields, an EPRI study reveals.
Such runoff can degrade surface water quality and cause algal blooms. These have led to the temporary loss of drinking water in Toledo, Ohio and the creation of ecological “dead zones” in the Gulf of Mexico and Lake Michigan.
Laboratory research had indicated that applying flue gas desulfurization gypsum to agricultural fields can reduce phosphorus runoff. Since 2006, the electric power sector has tripled its production of gypsum as it removes more sulfur dioxide from flue gas to meet new emissions requirements. Half of this gypsum is disposed in landfills.
EPRI worked to measure the effectiveness of this gypsum at working farms, applying it on eight Ohio farms and monitoring phosphorus concentrations in edge-of-field drainage over three years. Concentrations in most fields were reduced by 20–95% relative to control fields. The magnitude of the reductions diminished somewhat after three years, indicating that reapplication may be necessary. There was no significant effect on crop yields.
For a decade, EPRI and The Ohio State University have studied gypsum application at a network of farm sites in seven states, finding no adverse environmental impacts to soil, water, and plant quality. Informed by this work, the Natural Resources Conservation Services (part of the U.S. Department of Agriculture) in 2015 established a national standard that enables state programs to reimburse farmers for gypsum application. To help states facilitate gypsum use in water quality trading initiatives, EPRI plans to compile more detailed field data on phosphorus reductions.
Artwork by Kirk Anderson