The energy content (density) of
materials is a very important characteristic to meet our energy demands. Human
activities are dependent on several forms and sources of energy to perform
work. The energy content of an energy source is the available energy per unit
of weight or volume. Thus, the more energy consumed the more work that can get
done. There are four types of physical work related to human activities which
include: modification of the environment, appropriation of resources,
processing resources and transfer. Based on the thermodynamic concepts we can
rate the following from highest to lowest.
Gasoline: 45.4 MJ/Kg
Compressed Natural Gas (CNG): 53.6 MJ/Kg
Ethanol: 30.0 MJ/Kg
Lithium Ion Battery: 0.72 MJ/Kg
