Sub-bituminous coal is lignite that has been subjected to an increased level of organic metamorphism. Reserves are found mainly in six US western states and Alaska. It is used primarily as fuel for steam-electric power generation. It has carbon content ranging from 35 to 45 percent and a heat value between 8,300 and 13,000 BTUs-per-pound. Although its heat value is lower than bituminous coal, it contains lower sulfur levels which makes it more environmentally-friendly.
Exchange-traded sub-bituminous coal include the Powder River Basin coal, found in the region located in southeast Montana and northeast Wyoming, and Indonesian sub-bituminous coal, delivered FOB into ships from a range of East and South Kalimantan ports (Borneo). Both are traded at the ICE Europe.