This course is a material science approach to the challenge of energy efficient technology. It introduces the concept of materials energy content ( production,processing,use and recycling), description of how advanced materials make possible efficient energy harvesting (e.g, solar cells, nuclear materials, hard materials for oil/gas recovery, compo For wind Energy, thermoelectric), energy transformation (e.g, fuel cells, light emitting diodes, engines and turbines) and energy storage (e.g, hydrogen storage, phase change materials). Finally, materials enabling energy-efficient transportation and housing are discussed.