In this review, hydrogen has been considered as a 'clean' energy source and carrier and discussed in comparison with present day energy sources mainly based on fossil fuels and nuclear energy. In particular, the environmental and safety issues connected with both nuclear power and coal gasification plants, such as those due to nuclear wastes, acid rain and carbon dioxide, have been considered. Conventional as well as advanced methods of hydrogen production have been examined, attention drawn to direct hydrogen production from alternative energy sources, and an overview provided on the state of the art. A brief insight into hydrogen storage and distribution as well as into conversion and utilization concludes the review.