The aim of this project is to evaluate the economical, technical and environmental parameters that concern the development of a complete "Hydrogen Economy" System. In this System, Renewable Energy Sources are used to produce Hydrogen in a sustainable way  in order to cover the energy demands in Remote Areas concerning the Electricity and Transportation sector. In specific two hypothetical scenarios were studied in two Greek islands with autonomous electric grids. System modifications and developments were proposed while an economical and environmental analysis followed in order to assess the economical viability of such a System and the environmental benefits from the use of Renewable and Hydrogen technologies.