This Journal is a collection of papers about innovation, research, development and available evidence in the field of energy conversion and storage, optimal use of energy resources, analysis and reduction of environmental pollution and sustainable energy systems. In this Journal, a wide range of topics including systems and new technologies for the use of both fossil fuel sources and renewable energy to industrial and domestic uses of energy without the least destructive effect on the environment have been discussed. Also, topics such as modeling and forecasting methods, increasing the penetration rate of renewable energies, storage strategies and the economic, environmental and social effects of energy consumption policies such as reducing climate changes and reducing air pollution have been addressed.