Nowadays most of the decisions in the field of energy supply lead to an increased use of renewable energy resources. Such decisions imply several consequences for instance in electrical power generation. Indeed, replacing conventional energy sources by more stochastic ones has many impacts on the energy ressources managment. Guaranteeing an uninterrupted power flow to the consumer tends to be harder due to sudden changes of the power balance. A response can be found in adding several storage units within the power grid. As a matter of fact, energy storage systems have received a growing interest in the last few years. Consequently, the use of energy storage systems involves and requires fast energy transfers such as during the charge of a battery. This latter issue is the key point of the present work whose focus will be set on intermittent energy sources, which are thightly linked with the use of energy storage devices. First of all, several tools will be developed in order to characterize the energy transfer between two energy sources. These ones will highlight efficiency of powering several kind of loads. In order to solve the issues related to conventional power supplies, the focus will be set on systems made of several types of energy sources — or hybrid systems. The degrees of freedom of such solutions will be underlined and a classification of hybrid systems will be proposed. In order to illustrate the use of hybrid power supplies, an example will be studied and its sizing will be emphasized. Within that specific case, a fast energy transfer will be investigated. Being given the high level of sollicitation of energy storage units, this energy transfer turns out to be the key point of the development. In order to generalize the comments on the fast energy transfer, the scope will be set on the power supply of intermittent loads. Several solutions for the power supply of such loads will be commented. A new approach with embedded storage will be proposed for powering highly intermittent loads at low frequency. This system will be investigated and modelled during the last part of this work. An experimental validation of a two-stage power supply with embedded storage will be set up. This latter will interface a low power source with a high power load. Although this connexion seems to be impossible, the experimental set-up will demonstrate that the two-stage power supply allows interfacing such systems. Finally, a power amplification ratio will be introduced, which illustrates the capability of the system to generate a much higher power than its power supply is able to provide.