Mixing semi-dry flue gas desulfurization solids with fly-ash from coal-fired power plants creates a contaminated solid waste that is usually landfilled. A study compared three scenarios to monetize this waste: a standard power plant, a plant treating spray dryer solids thermally, and a plant bypassing desulfurization. The study found that the standard plant was the most harmful to the environment due to solid waste production, while the plant treating spray dryer solids was the most environmentally friendly but required more investment. Bypassing desulfurization increased certain environmental impacts.