Characteristics of Energy Resources

The main characteristics of energy resources that have a main impact on decision-making in energy matters are as listed below:

• Concentration

Energy per unit volume or per unit mass: for stock-type resources.
Energy flux: for flux- type resources.

• Quality

The fraction of total energy available for conversion to work.
Measure: energy per unit entropy. (Associated to T)

• Ease of Extraction
• Ease of Transport
• Ease of Use
• Adequacy of Supply
• Material process per unit of energy extracted

There are main differences among the characteristics of various energy resources. For illustration, whereas the potential energy of 1 kg of water at 100 m elevation is 0.981 kJ, the chemical energy of 1 kg of fuel oil is 41,000 kJ. The chemical energy has its beginning in the bond energies of the product molecules in association to those of the reactant molecules in the chemical reactions. The chemical energy sources, like fuels, therefore symbolize highly concentrated forms of energy. To give an easy illustration, the power transfer during the filling of the petrol tank of a car at the rate of 10 liters in one minute amounts to as much as 5.48 MW. To give the other illustration, to show the energy density of chemical fuels, the energy of fuel in a little cigarette lighter is equivalent to the electrical energy stored in six fully-charged automobile batteries.

The three different energy sources are compared below in terms of their concentration (stated as energy per unit volume):

• Solar energy   :  10^-12 kJ/m³
 • Coal              :  104 kJ/m³
 • U-235            :  4.4 × 10¹¹ kJ/m³