Long-term, reliable and rational fulfilling of demand for energy is an indispensable condition for existence and progress of the whole world, especially considering industrial and technological fields. In the 21st century, the energy generation sector is undergoing thorough and revolutional changes, especially after the breakthroughs in the second half of the 20th century.The ecological principles, which are gaining great importance, are gradually supressing the conventional technologies in the field of energy exploitation. To date, the results in the advancement of renewable energy technologies are a great promise for the future. In this undergraduate thesis, special attention is given to the energy system intended for the supply of an isolated island, which primarily uses water and wind energy for the purpose of electricity generation. First, from the perspective of mechanical engineering, the major elements of such an energy system were separately considered and their mode of exploitation of the appropriate form of energy was explained. Subsequently, all parts were combined into one functional unit and based on the insights from the previous chapters, the principle of operation of the entire energy system was determined. Finally, a simplified model of such a system was designed and analysed on the basis of technical parameters originating from the official energy statistics of the Republic of Croatia. The results of such an analysis clearly illustrate the possibilities and potentials of using water and wind for small energy systems.