Link between Energy Storage and System Property

6 Link between Energy Storage and System Property 

For effectively storing energy, a system must possess a constitutive property that is specific to each subvariety. When a system is not endowed with such a property, no corresponding energy can be stored in it. 

The point is that the absence of a system property in a system does not mean that the corresponding entities are absent, or even that the associated energies-per-entity are equal to zero. If the two state variables are not connected, the energy in this subvariety cannot vary in the systan, and therefore remains constant. This principle is illustrated in Graph 3.2. 

This means that it is not a conceptual difficulty to admit the existence of state variables for energy varieties that have never been evidenced, as we have done in Chapter 2, Tables 2.1 and 2.2 listing entity numbers and energies-per-entity respectively. 

if some subvarieties have not been experimentally identified, this is either because of the nonexistence of systems possessing the right property or naturally because of the experimental difficulty to evidence it. This is owing to the fact that a constant energy has effect only to shift the origin of scale and only a variation of energy can be detected. 

---