Petroleum coke refers to all types of carbonaceous solids obtained in petroleum processing, which include green or raw, calcined and needle petroleum coke. Petroleum coke is used in many applications, including electrodes and anodes. It is also used as a fuel in the metal and brick industries. It consists mostly of carbon, with variable amounts of sulfurs and heavy metals. It has many industrial uses, including the production of batteries, steel, and aluminum. Lower-grade petcoke, which contains higher concentrations of sulfur, is used as fuel in coal-fired power plants and cement kilns.