This book provides a state-of-the-art review of the applications of electrospun nanofibers for piezoelectric and triboelectric energy harvesting. It comprises eight chapters and covers the basis of electrospinning, nanofibers, piezoelectricity, triboelectricity and the emerging research on the use of nanofibers in energy harvesting devices. It is a key reference for graduate students, researchers and scientists in the fields of energy harvesting, sensors or nanofibers, and it will benefit industry specialists involved with energy materials and energy conversion technology.