Coal was a fossil fuel that had been used since 1750. In the early 21st century, it was being replaced.
Before there was coal, there was wood. Caveman used wood for their fires. To get wood, they had to cut trees. Wood was also used to build houses, boats, and carts. The invention of the wheel by the Sumerians would not have been possible without wood. Wood was one the most common fuels to light a home, too. A lot of wood was cut to fuel fires. Axes became more sophisticated, too. However, wood could not last forever, so a new fuel source had to be found. That was where coal came in.
Tech Level: 7-10
In the 1700s, Britain was the biggest miner of coal in Europe and the world. Britain started using the steam engine to power its factories. With very little wood in Britain, coal would work better. Coal was used to power the steam engine. Soon, the steam engine went beyond the factory. As industry spread throughout Europe, the steam engine appeared in ships and in trains. In the 1900s, battleships and power plants started using steam turbines which used coal to heat water into steam to turn a turbine which turned a generator. Even as the steam engine became obsolete, coal continued to be used for electricity. There was one problem. The burning of coal was a contributor to global warming. The solution was clean coal technology. In September 2008, in Germany, the Swedish company Vattenfall built a power plant that ran on clean coal. The purpose of the technology was to eliminate the emissions that were normally created by burning coal. Clean coal would help clean the environment. However, there was another fossil fuel that was causing more trouble than coal: Petroleum.