Microbial Conversions of Low Rank Coals

Coal is the United States' most abundant nonrenewable energy resource. However, the quality of many coals is too low to offset the practical, economic, and regulatory barriers to their utilization. A variety of bacterial and fungal species have been shown to attack low rank (i.e., low–quality) coals. Technologies based on these microbial activities may be useful for the conversion of these coals to more useful products, including high–quality fuels and chemicals. Substantial developmental work will be required in order for these microbial processes to become competitive with nonbiological processes. This review summarizes the microbiological and biochemical principles underlying microbial coal conversion as a basis for predicting the practical utility of coal bio–processes.