With an electrostatic precipitator fly ash particles are given an electrical Charge as the gases pass through the precipitator. Thus, the particles are collected rather than discharged to the atmosphere. A baghouse on a Power plant contains a large number of filter bags. The combustion gases are passed through the bags and the fly ash particles are trapped by filters. Periodically, the material collected by the precipitator or the baghouse is emptied into a collecting bin, or hopper, where it can be removed.
Utilities can reduce sulfur dioxide emissions by switching to coal with a lower sulfur content.
Unfortunately, there is a limited supply of low-sulfur coal and it cannot be transported cheaply to all areas of the country. An alternative to buying low-sulfur coal is cleaning some of the sulfur out of the coal before it is burned. This is possible because the sulfur in the coal exists in two forms, organic and pyritic. Organic sulfur is combined chemically with the structure of the coal itself and, unfortunately, cannot be separated by cleaning. Pyritic sulfur, however, exists as separate particles within the coal.