Coal's been generating controversy for about as long as it's been generating energy.
On April 20th 1914, coal was at the epicenter of the bloodiest battle in US labor history. It's called the Ludlow Massacre, after the mining town in Southern Colorado where coal miners went on strike demanding better conditions. The Colorado National Guard attacked a tent colony of striking miners and their families - 20 people were killed - most, women and children.
Interesting? Move right on to America's Deadliest Labor War which is an interview with the author of Killing for coal professor of history Thomas Andrews.
Also, I put it on the "curriculum". And the Ludlow massacre is on Wikipedia of course.