Recent developments make appear new devices for energy storage, such as supercapacitors. Those components are able to store a high energy density. Even if this energy is still lower than the energy batteries can store, thos components can be loaded and/or unloaded quickly. This paper proposes to define first how supercapacitors can be used to supply electric vehicle such as bus and tramways. This needs a fast loading in various stations, with a lot of constraints on a power supply. This is not always suitable, when a distributions network is not able to supply such a high power, or when the power supplied by a network must be limited. In a second part, we propose a method for loading energy in supercapacitors with a high power by taking a low power on a distribution network, using also supercapacitors as energy buffers. Then, various energy exchange laws are discussed, to show how to optimize the loading time of the "on-board" supercapacitors, and to minimize the number of supercapacitors in each loading stations.