Although underground coal mines operations are not as visible as surface mining, their overall environmental impact can be greater than that of the typical surface mine. A key environmental problem is subsidence. Underground mines are large cavities in the rock, and depending on the strength of the intervening strata, the depth of the mine, and the type of mining and roof support, the rock walls can fail, causing cracks and land collapse at the surface. Typically, coal seams at depths greater than about 200 feet are extracted by underground mining methods rather than by surface mining, with the exact depth principally based on the relative amount of coal and overburden. However, before improved technology made surface mining so affordable, the trade-off occurred at much shallower depths; some abandoned underground mines are only 35 feet below the land surface. (more…)

Coal is an important energy source and energy consumption in United States as well as worldwide. It will remain so for many years particularly in many developing countries. Fossil fuels stay as the main energy sources to the U.S. economy, but we can not ignore the importance of coal for decades. Coal production provides the price stability and will continue to be an significant source for electricity generation. Coal utilization is the major source of hydrogen in the coming hydrogen-based energy economy and it will be a crucial source of gas to liquid process of fuels energy.

Coal utilization and the importance of coal as source of energy industry perspective will change over time. (more…)