Energy Excursions

Primary Versus Secondary Energy

Now that you have a thorough understanding of the definition of energy and some of the units of measure, let’s turn the focus towards the difference between primary and secondary energy. Simply put, primary energy is energy that can be created and derived from nature, whereas secondary energy, such as electricity has been converted, or generated, from a primary source. Essentially, primary energy is transformed into secondary energy to be consumed by us, whether it’s to heat our homes, fuel our cars, or turn the lights on.

Primary Energy 

By definition, “primary energy is an energy form found in nature that has not been subject to any human engineered conversion process. It is energy contained in raw fuels and other forms of energy, including waste, received as an input to the system. Primary energy can be non-renewable or renewable.”1Wikimedia Foundation. (2021, August 18). Primary energy. Wikipedia. https://en.wikipedia.org/wiki/Primary_energy.

According to the Energy Information Administration (EIA), primary energy sources include:2U.S. energy Information administration (EIA ) independent statistics and analysis. U.S. energy facts explained – consumption and production. U.S. Energy Information Administration (EIA). (n.d.). https://www.eia.gov/energyexplained/us-energy-facts/ 

  • Petroleum 
  • Natural gas 
  • Nuclear electric power 
  • Coal 
  • Wind 
  • Hydroelectric 
  • Wood 
  • Biofuels 
  • Solar 
  • Biomass waste 
  • Geothermal 


In 2020, the United States consumed 92.94 quadrillion BTU’s of primary energy, with 11.59 quadrillion BTUs consisting of renewable primary energy sources.3U.S. energy Information administration (EIA) independent statistics and analysis. U.S. energy facts explained. U.S. Energy Information Administration (EIA). (n.d.). https://www.eia.gov/energyexplained/us-energy-facts. 

What single renewable primary energy source was consumed at the highest rate in 2020? 

Wind

Correct. 

Petroleum

Incorrect. 

Biomass

Incorrect. 

Biofuels

Incorrect. 

_________ was consumed at 3.5 times the rate of coal in 2020. 

Hydroelectric

Incorrect. 

Natural gas

Incorrect. 

Petroleum

Correct. 

Biomass

Incorrect. 

Currently in the United States, the majority of the primary energy sources we convert into secondary energy are fossil fuels. Natural gas has been on the rise in regard to primary energy production, as shown in the graph below, whereas coal production has significantly declined. 

Secondary Energy 

Primary energy goes through various conversion processes to be converted into secondary energy, the type of energy we use on a daily basis at our homes, at work, and at many leisure activities. According to the EIA, “the electricity that we use is a secondary energy source because it is produced by converting primary sources of energy such as coal, natural gas, nuclear energy, solar energy, and wind energy, into electrical power. Electricity is also referred to as an energy carrier, which means it can be converted to other forms of energy such as mechanical energy or heat.4Secondary energy – energywiki. Userwikis der Freien Universität Berlin. (n.d.). https://userwikis.fu-berlin.de/display/energywiki/secondary+energy. Another example of secondary energy is gasoline, a byproduct of refining crude oil that we use to fuel our automobiles. 

In 2020, the United States produced 4.12 trillion kilowatt-hours (kWh) of electricity, with the main energy source consisting of natural gas, followed by nuclear and renewables.5U.S. Energy Information administration (EIA) independent statistics and analysis. What is U.S. electricity generation by energy source? U.S. Energy Information Administration (EIA).  (n.d.) https://www.eia.gov/tools/faqs/faq.php?id=427&t=2   

What percentage of electricity generation in 2020 was produced by geothermal? 

0.4%

Correct. 

1.4%

Incorrect. 

7.3%

Incorrect. 

19%

Incorrect. 

Which fossil fuel source comprised the lowest percentage of electricity generation in 2020? 

coal

Incorrect. 

biomass

Incorrect. 

nuclear

Incorrect. 

petroleum

Correct. 

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