Direct contact with the object is not necessary for the heat transfer to occur. The flow of energy across open space via electromagnetic waves such as light. Passage of heat from one object to another without warming the air space in between. Bituminous Coal is soft, the most common type found in the United States, and is used to generate electricity and to make coke for the steel industry. Subbituminous is a coal with a heating value between bituminous and lignite, and has low fixed carbon and high percentages of volatile matter and moisture.
Subbituminous coal is used primarily for generating electricity.
Lignite is the softest coal and has the highest moisture content. It is used for generating electricity in certain parts of the country and for conversion into synthetic gas. In terms of Btu or ''heating'' content, anthracite has the highest value, followed by bituminous, subbituminous and lignite. The value of property upon which a utility is permitted to earn a specified rate of return as established by a regulatory authority. Depending on which method is used, the rate base includes cash, working capital, materials and supplies, and deductions for accumulated provisions for depreciation, contributions in aid of construction, customer advances for construction, accumulated deferred income taxes, and accumulated deferred investment tax credits.