In the earlier days coal might have been used for providing heat for making food or in the blacksmiths furnace but as technology made strides, so did the level and importance of coal in the energy production arena went upwards. Currently thermal power plants produce hundreds of megawatts of electricity from burning coal.
Despite the hue and cry of environmental concerns, which are of course true to a certain extent, various other parameters have still kept coal as one of the most important sources of power generation in thermal power plants.
The very first parameter is the ample abundance of coal in most parts of the world including the United States. Estimates suggest that the US has reserves of coal which could last more then two centuries even at the current rate of consumption. Apart from the reserves found on land there is also presence of coal layers beneath the sea although it is difficult to commercially extract it from there, but there might be a technology for this in the future.
The next factor is directly related to the above factor and is that of cost. As you know cost is closely associated with availability and more abundant any commodity is, the lesser will be its price and vice versa which is a law of economics. Hence producing electricity through the use of coal is much cheaper than other non-conventional forms of energy such as say wind, nuclear and so forth.
