injected into the lower portion of the combustor for initial burning of the fuel. The combustion actually occurs in a bed of fuel, sorbent, and ash particles that are fluidized by air nozzles in the bottom of the combustor. The air expands the bed, creates turbulence for enhanced mixing, and provides most of the oxygen necessary for combustion of the fuel. As the fuel particles decrease in size through combustion and breakage, they are transported higher in the combustor where additional air is injected. As the particles continue to decrease in size, unreacted fuel, ash, and fine limestone particles are swept out of the combustor, collected in a particle separator (also called a cyclone), and recycled to the lower portion of the combustor. This is the "circulating" nature of the combustor. Drains in the bottom of the combustor remove a fraction of the bed composed primarily of ash while new fuel and sorbent are added. The combustion ash is suitable for beneficial uses such as road construction material, agricultural fertilizer, and reclaiming surface mining areas. The limestone captures up to 98% of the sulfur impurities released from the fuel. When heated in the CFB combustor, the limestone, consisting primarily of calcium carbonate (CaCO3), converts to calcium oxide (CaO) and CO2 . The CaO reacts with the SO2 from the burning fuel to form calcium sulfate (CaSO4), an inert material that is removed with the combustion ash. The combustion efficiency of the CFB combustor allows the fuel to be burned at a relatively low temperature of about , thus reducing NOx formation by approximately 60% compared with conventional coal-fired technologies. Greater than 99% of particulate emissions in the flue gas are removed downstream of the combustor by either an electrostatic precipitator or a fabric filter (baghouse). The heated combustor converts water in tubes lining the combustor's walls to high pressure steam. The steam is then superheated in tube bundles placed in the solids circulating stream and the flue gas stream. The superheated steam drives a steam turbine-generator to produce electricity in a conventional steam cycle. Fuel supply The plant uses a continuous ship unloader, the only one of its type in the continental United States. The solid fuel is transferred from barges onto the fuel conveyor system, which in turn transports it to the two largest fuel storage domes in North America. Pet coke and coal travel from the ship to