coal: USA critical source ?

"Coal keeps US economy burning?" that is an interesting article from BBC.

Summary: coal is playing a major role in substaining US economy. It is cheap (cheaper than Gas and Oil) , based on consolidated technolgy and is used to generate 52% of America's electricity.

But Energy operators complain that "supplies are not meeting demand, leaving them low on reserves and Americans potentially exposed to power shortages."

Furthermore getting the coal to its destination is a massive logistical challenge.

And coal is (at least to date) not clean..

Source [ Rob Cameron - BBC News]