The overall efficiency, effectiveness, and practicality of potential future energy sources and systems are directly related to many materials-related factors. This volume features 30 papers presented during the 2012 Materials Challenges in Alternative and Renewable Energy Conference. They cover the latest developments involving materials for alternative and renewable energy sources and systems, including batteries and energy storage, hydrogen, solar, wind, geothermal, biomass, and nuclear, as well as materials availability, the energy grid, and nanocomposites.