Energy is one of the critical issues that directly impact the economy, the environment, and the security of human beings. All energy technologies require materials; therefore, the types and amounts of materials consumed vary widely. While materials science and engineering are only one aspect of the response to the energy challenges, it primarily has a crucial part to play in creating the advanced energy systems. In the past, it has contributed significantly to advances in the safe, reliable, and efficient use of energy and available natural resources. Now materials research is being performed from structural materials, functional materials to high photon energies, which can offer promising solutions to achieve accessible, renewable, and sustainable energy pathways for the future. Particularly, the growing importance of environmental issues is such that energy generation, conservation, storage, and security of supply will continue to be major drivers for materials technology. Sustainable energy production and use are needed while at the same time meeting socioeconomic and environmental targets: The high priority of energy makes it important to sustain research, development, and modeling of materials for energy applications; the knowledge-base of high-integrity structural and functional materials should be recovered, captured, and developed for future power generation; transferable material solutions and methods across the complete energy portfolio should be examined to attain maximum efficiency and competitive advantages. With the advent of nanomaterials and innovative multifunctional materials, materials science and engineering is expected to play an increasing role in sustainable technologies for energy generation, storage, and distribution, as well as efficient utilization of future energy. Principal areas of advanced materials development include but not limited to sustainable structural and functional materials for fossil power, solar energy, wind energy, geothermal energy, biofuels, ocean energy and hydropower, nuclear power, as well as advanced energy-harvesting technologies. This chapter will introduce fundamentals and basic design guidelines of advanced energy systems with accompany of materials solutions and environmental compliance of energy materials.