Stronghold burns coal remains from centuries of mining in Pennsylvania, preventing the sometimes 200-feet deep piles of waste from poisoning the soil and emitting harmful chemicals into the atmosphere.

Waste coal is more toxic to the environment than “new” coal, containing mercury, sulfur, and lead, to name a few.

It is also burned in what is known as a fluidized bed, where combustion takes place to convert the waste coal to energy, a process requiring more energy than burning traditional coal.