The term 'Fuel Storage Unit' can be summarized as a coalbin, which is a seven-letter word. A coalbin is a structure used to store coal, which is a combustible black or brownish-black sedimentary rock that is composed mostly of carbon and hydrocarbons. Coalbins are typically found in industrial settings, such as power plants, factories, and other places where coal is used as a fuel source. Coalbins are also used to store other types of fuel, such as wood, oil, and gas.