1Introduction Energy enters our lives in many different ways Energy in food: essential for the existence of all humankind and animals throughout our evolution on this planet Energy in engine fuel: power automobiles, heat homes manufacture products, generate electricity The fossil fuels: coal, natural gas, and oil supply most of the energy used globally(86% in the United States) These resources evolved hundreds of millions of years ago Since the beginning of the machine age, industrial societies have become increasingly dependent on fossil fuels1. Introduction Energy enters our lives in many different ways. • Energy in food: essential for the existence of all humankind and animals throughout our evolution on this planet. • Energy in engine fuel: power automobiles, heat homes, manufacture products, generate electricity … The fossil fuels: coal, natural gas, and oil supply most of the energy used globally (86% in the United States). • These resources evolved hundreds of millions of years ago. • Since the beginning of the machine age, industrial societies have become increasingly dependent on fossil fuels