To compare storage systems, Ragone’s diagram is generally used to represent performance in terms of
the ratio of mass to energy and power [26]. This type of conventional comparison is particularly
interesting for portable units, for which mass is a critical aspect, but for permanent units, in a context
of electrical-energy processing, life expectancy and total costs (investment, energy losses, and cyclingfatigue) are the most important criteria [27]. Thus, these comparisons, overly simplistic, do not reach a
definitive conclusion about the validity of the choice of compressed air to associate with a wind-diesel
hybrid system. For this reason, a thorough and detailed summary will be presented in the next sections
explain the selection of compressed air while based on techno-economic criteria listed above.