Energy Sources
Primary Energy Sources
Energy as we find it in nature.
Examples: coal, oil, wind, and sunshine
Secondary Energy Sources
Energy sources converted from primary sources.
Examples: electricity, gasoline, hydrogen
Energy Services
These are the benefits provided by energy.
Examples: air conditioning, transportation, lighting
Efficiency
One definition of efficiency is the ratio of secondary energy to primary energy in the conversion process.
Fossil Energy
Resources buried in the earth that are not being renewed at a significant rate
Renewable Energy
Energy flows that are considered inexhaustible
Resources
Potential energy accumulations in the earth, especially fossil.
Reserves
Resources that have been proven economically viable through exploration are called reserves.