The paper describes a preliminary feasibility analysis of a nano-GT (50÷200 W) for portable power generation. The system is examined under both a thermodynamic and an operative point of view. The technical problems posed by a practical implementation of an operative system are assessed first via a preliminary calculation of the overall thermodynamic performance of the real cycle, and then via a first-order design of the main components. The extremely small size of the device makes a preliminary estimate of the components performance problematic (the available data are scant and unreliable): it is likely that a real advance in this field must go through a series of detailed fluid-dynamic simulations. The results of our preliminary sizing are compared with the existing technical literature in an attempt to further define the material selection, in view of a possible prototype production. Some considerations are also offered about the final utilisation of nano-GTs: in our opinion, they represent a realistic alternative to batteries for powering optical, GPS and other satellite devices, or in medical applications.