Chapter : Fossil Fuels Chemistry LibreTexts
The total expenditure of energy in the world each year is about 3 × 10 17 kJ. Today, more than 80% of this energy is provided by the combustion of fossil fuels: oil, coal, and natural gas (The sources of the energy consumed in the United States in 2009 are shown in Figure ) but as Table from the Wikipedia shows, energy usage is a complex issue.