This contribution highlights the key role that batteries and supercapacitors are playing for renewable energy plants, both stand alone and grid connected, and for a sustainable transportation by hybrid electric vehicles (HEV). The advantages of wind farms that use batteries as energy storage systems are presented as well as the energy return factors expected for stand alone photovoltaic plants with different battery technologies are reported. The advances in R&D of high-power lithium ion batteries and high-energy supercapacitors for HEV application are even discussed and some experimental results from our laboratory are presented.