There's no question that this coal will be used. Today, the Department of Energy estimates that the United States possesses nearly 31 percent of the world's known recoverable coal reserves. Despite an increasing concern about the deleterious effects of its combustion on the environment, coal continues to occupy the second largest American market share for fuel, behind only petroleum. These questions interest Mastalerz and other geologists for their pure research value, but the answers contain information vital to the coal industry. The lowest rank, lignite, often contains fragments of original plant remains, is moister, and burns less efficiently than harder coals, resulting in the lowest heating value.
Bituminous coals are denser and produce higher heating values suitable for industrial combustion.
A hard, lustrous coal called anthracite ranks highest due to its high carbon content. Ongoing study of the ancient conditions and processes that led to coal formation has enabled geologists to develop and refine a predictive model for locating coal with specific qualifications. We now know where the coal basins are. There are few places left in the world where exploration for major resources has not already taken place. In Europe, for example, I think we have looked at the same rocks two, maybe three times.