Book excerpt: Carbon materials play a significant role in the development of alternative clean and sustainable energy technologies. This new volume focuses on the new applications of different carbon nanomaterials and graphene-carbon-nanotube hybrids for energy generation, energy storage, and energy conversion. It presents a comprehensive overview of recent developments on carbon-based nanomaterials with a focus on sustainable and clean energy applications. With chapters written by the leading academicians and researchers working in the field, the volume explores state-of-the-art developments using both commercially available and emerging materials and their potential applications for energy storage and energy harvesting.