Coal has been used mostly to generate power supply. Now a days US as a large amount of coal with that it can survive for more than 200yrs and one more thing is that it can be converted into liquids and gases and also into diesel.Most people do not realize that when they use electricity, they are probably also using coal. Of the coal that is not used to make electricity, most is used to make steam for heating, as coke in steel making, or is exported. In developing countries half the world's population depends on coal for heat. Here is a link that might be useful: Coal Mining