This book overviews the latest progress in waste energy harvesting technologies, with specific focusing on waste thermal mechanical energies. Waste mechanical energy harvesting technologies use the piezoelectric (ferroelectric) effect with ferroelectric materials and nanogenerators. Thermal energy harvesting technologies use the thermoelectric effect, the pyroelectric effect and storage through phase change materials. The book aims to strengthen the syllabus in energy, materials and physics and is well suitable for students and professionals in the fields.