Sustainable development is, by any definition, in the focus of interest in the 21st century, as it is a matter of the survival of mankind. One has to keep in mind, that global population is currently about 7.6 billion, whilst a century it was less than 2.0 billion; furthermore, more than three quarter of the world's population is living in cities. Thus, what lies in the road ahead for the coming 100 years? It is more than clear, that the impact of the human activities on the limited resources and on the environment is forceful and be destructive for the future of the planet and the population that is supports. A novel approach is therefore needed, practically in all aspects of life. Energy is undoubtedly a starting point for the global economic growth and the wellbeing of people, it is however our task to make this economic growth possible on a sustainable base and with reduced harmful impacts. In this line of approach the use of clean and inexhaustible energy resources, coupled with the increase in energy efficiency can and will lead towards a more sustainable future. Still, it is not just important to ensure clean energy, increase the energy efficiency and promote the smart waste of resources; it is also important to educate people and increase global awareness. Different engineering disciplines are called in to provide their input and the diffusion of fundamental and applied knowledge is needed to be able to respond to the present and upcoming challenges, which are usually complex and intertwined.