Primary & Secondary Energy Sources: What They Are, & Examples Of Each

Primary & Secondary Energy Sources: What They Are, & Examples Of Each

Energy sources can be primary or secondary.

In this guide we explain what they are and give examples of each.


What Are Primary Energy Sources?

Primary energy sources are usually either natural or refined resources.

They undergo an energy conversion process to produce a secondary (usually more convenient) form of energy.


What Are Secondary Energy Sources?

Secondary energy sources are forms of energy produced from the above mentioned energy conversion process of primary energy sources.

Secondary energy sources are the ones we as humans usually directly use in a more convenient way e.g. the burning of coal at coal power plants is the primary energy source that delivers us the secondary energy source of electricity to use at work, in our homes etc.


Secondary energy sources are also referred to as energy carriers, because they move energy in a useable form from one place to another [secondary energy is essentially a good that has been changed from it’s original state to another state for ease of consumption]. The two most well-known energy carriers are electricity and hydrogen.



What Are Examples Of Primary & Secondary Energy Sources?

  • coal, raw oil, natural gas, wind, sun, streaming water, [… and uranium are all examples of primary energy sources]



  • Gasoline is a secondary product better suited for motor transport uses than crude oil, the primary product from which it is made.
  • Electricity production based on hydropower, solar PV, wind and ocean energy is considered to be primary energy.
  • For geothermal and solar thermal, however, heat is the primary energy, which can be transformed into secondary geothermal or solar electricity.
  • [Bioenergy is a more complicated/complex form of energy as not all bioenergy sources are primary energy products]



  • Primary sources can be used directly, as they appear in the natural environment: coal, oil, natural gas and wood, nuclear fuels (uranium), the sun, the wind, tides, mountain lakes, the rivers (from which hydroelectric energy can be obtained) and the Earth heat that supplies geothermal energy.
  • Secondary sources derive from the transformation of primary energy sources: for example petrol, that derives from the treatment of crude oil and electric energy, obtained from the conversion of mechanical energy (hydroelectric plants, Aeolian plants), chemical plants (thermoelectric), or nuclear (nuclear plants). Electric energy is produced by electric plants, i.e. suitable installations that can transform primary energy (non-transformed) into electric energy.



  • People make electricity and hydrogen [which are secondary energy sources] from primary energy sources such as coal, natural gas, nuclear energy, petroleum, and renewable energy sources (biomass, geothermal, hydropower, solar energy, and wind energy).



  • Crude oil must be put through an oil refinery before it turns into secondary fuel (useable fuel) like gasoline, diesel or kerosene.
  • Coal is usually put into a coal-fired power plant to generate electricity
  • Wind must be harnessed by a wind turbine before it can generate electricity



  • Primary energy sources take many forms, including nuclear energy, fossil energy – like oil, coal and natural gas – and renewable sources like wind, solar, geothermal and hydropower. These primary sources are converted to electricity, a secondary energy source, which flows through power lines and other transmission infrastructure to your home and business.



There’s some good examples of primary energy sources, energy breakdown processes and secondary energy sources at:



What Does It Mean To Say That Electricity Is A Secondary Energy Source?

It means that electricity is the source of energy being used by the consumer, but it has come from a primary energy source such as coal (that has undergone an energy conversion process at a coal power plant) for example.













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