Today the utilization of renewable energy sources is very important to support the traditional ones, and also in order to reach the objectives fixed by the Kyoto Protocol. In this context, also well-known technologies related to the electric energy production, formerly not suitable - due to the poor technological level of the components or due to the high costs linked to the system efficiency - may now find a suitable collocation. Among these technologies, the thermoelectric effect may be very advantageous in some particular applications of small power. A power generation system utilizing this technology has been studied by the authors. This system utilizes the thermal difference between a lower temperature sink, e.g. a water reservoir, and a higher temperature source, such as exhaust heat (e.g. from industrial processes) or as produced by solar energy captured by an extended surface. The thermoelectric generator is made up of thermocouples placed on the internal surface of a tubular heat exchanger, located inside the water body and filled up with hot water coming from the energy source. In this paper, the physical mechanisms and the energy balances governing the system are described in order to evaluate its energetic feasibility. Once fixed, the electrical power required by the end user, the system parameters are optimized with the aim to have the most compact equipment and components. A simulation of the proposed system was performed referring to the city of Palermo, Italy. A very poor economic convenience of the system has been found in this applications. (C) 2014 Elsevier Ltd. All rights reserved.