Lignite as a primary energy source is expected to play a key role in energy supplies in the future because of its abundance, easy exploitation, and low mining cost. Lignite is characterized by high moisture content and a low energy yield compared with other coals, although cheap and low in sulfur. This moisture enhances the freight charges per thermal unit of coal and direct combustion of wet lignite for electricity generation may not be energy efficient because a significant portion of fuel energy must be ...