Primary energy is energy contained in raw fuels and any other forms of energy received by a system as input to the system. The concept is used especially in energy statistics in the course of compilation of energy balances.
Conversion to secondary energy
Primary energies are transformed in energy conversion processes to more convenient forms of energy, such as electrical energy and cleaner fuels. In energy statistics these forms are called secondary energy .
It will be important to replace the fossil coal fuels during the 21st century with good alternatives, for example nuclear fusion plants.
Levels and flows
Levels (reserves in the ground) and flows (production) of primary energy sources. The most important part of primary energy sources are the coal based fossil (old) energy sources. Oil, coal, and gas stood for 79.6% of primary energy production during 2002 (in million tonnes of oil equivalent (mtoe)) (34.9+23.5+21.2).
Levels (reserves) (EIA oil, gas, coal estimates, EIA oil, gas estimates)
- Oil: 1,050.691 - 1,277.702 billion barrels (2003-2005)
- Gas: 6,040.208 - 6,805.830 trillion cubic feet (6,805.830*0.182= 1,239 BBOE) (2003-2005)
- Coal: 1,081,279 million short tons (1,081,279*0.907186*4.879= 4,786 BBOE) (2004)
Flows (daily production) during 2002 (7.9 is a ratio to convert tonnes of oil equivalent to barrels of oil equivalent)
- Oil: (10,230*0.349)*7.9/365= 77 MBD
- Gas: (10,230*0.212)*7.9/365= 47 MBOED
- Coal: (10,230*0.235)*7.9/365= 52 MBOED
Years of production left in the ground with the most optimistic reserve estimates (Oil & Gas Journal, World Oil)
- Oil: 1,277.702/77/365= 37 years
- Gas: 1,239,000/47/365= 72 years
- Coal: 4,786,000/52/365= 252 years
- BBOE - billion barrels of oil equivalent
- MBD - million barrels per day
- MBOED - million barrels of oil equivalent per day