The total amount of energy in the Universe always stays the same. In most of this story we are studying how energy changes from one form into another. If these changes did not happen there would be no story, no life, no Universe at all. We humans get most of our food energy from the Sun . Plants are capturing it in the process called photosynthesis .
Most rich countries rely to a large extent on fossil oil to run their economies.
This is the fossil remains of plants. Click here for some thoughts about sources of energy in the future.