One of the most common ways to produce heat and electricity in Europe today is by the incineration of waste or combustion of coal. These materials can be very sulfurous and during combustion sulfur dioxide is produced. This is an environmental and health related toxic substance which is why power plants have strict regulations on removing it from the flue gas. Sulfur dioxide is removed from the flue gas by adding a limestone reagent. The sulfur dioxide reacts with the limestone and the synthetic product obtained is ?Flue Gas Desulfurization gypsum?.