Elements than have been produced by nature, without the intervention of man.
Examples of natural elements are:
Electricity can be produced from Fossil Fuels, Water and gravitational force (Hidroelectricity), Wind, Sun (Solar), Geothermal energy, Biomass and waves and tides.
Radiation from the sun is also an important source of heat that can be used to heat water for domestic or industrial uses. Geothermal energy is also a source of heat, but it is available only in some geographical spots. Biomass is also a source of heat.
Fossil fuels play an important role in the economy, since they are extensively used to produce electricity, heat and motion. Fossil fuels are non renewable resources, since they were produced naturally millions of years ago, and are not renewed after it's use.