The global energy market is valued in excess of US$6 Trillion per year, not including exploration and development.
Demand is met by five, mainly fossil-fuel, sources. Fossil-fuels are a group of energy sources that were formed when ancient plants and organisms were subjected to intense heat and pressure over millions of years.
Other sources of energy include Nuclear energy, derived from nuclear reactions used to drive steam turbines to create electricity, and Renewable energy sources including Hydroelectric, Geothermal, Solar, Wind, Tidal/Wave and Biomass.
For more detailed insight explore our summary on Oil, Natural gas, Coal, Nuclear and Renewables.