Energy resources: A Fundamental fact - Human society is a manifestation of the Biosphere. Not surprisingly, we derive almost all of our energy from the Sun.

Prior to the industrial era, all of the energy being harnassed by humans (muscle, wind, water power) had been beamed to Earth from the Sun very recently, at most within the few centuries. And that's where matters stood until the 18th century when steam power was harnassed to allow the industrial revolution:

Fossil Fuel: For the first time, humans were making use of energy that was truly ancient - that had been beamed from the Sun millions to hundreds of millions of years earlier - "fossilized energy, if you will. Such energy sources are called Fossil Fuels.

Since then, most innovations in energy production have involved finding different ways to turn turbines and push pistons harder and faster, and finding different things for those turbines to do. Thus, an electrical power station is steam turning a turbine turning an electrical dynamo. What makes that steam can be anything from a wood fire (rare these days) to the fission of heavy metals in a nuclear reactor.

The paradox of fossil fuels: In the preindustrial era, energy was stored as carbohydrates in plant tissues which were built from atmospheric CO2 and H2O. Both are "greenhouse gasses." When plant tissue decomposes, is digested, or is burned, the gasses are restored to the atmosphere. What happens when the tissue is sequestered in the rock record?

Coal: Metamorphosed remains of rapidly buried land plants.