This book on energy science and engineering is written to provide a grounding in the foundations of this subjects. This book is suitable to AKTU students for all the years of students.This book provides a quantitative yet accessible overview of renewable energy engineering practice and the technologies that will transform our energy supply system over the coming years. Covering wind, hydro, solar thermal, photovoltaic, ocean and bio- energy, the text is suitable for engineering undergraduates as well as graduate students. Worked examples of the simple techniques used to calculate the output of renewable energy schemes engage students by showing how theory relates to real applications.The origin and continuation of humankind is based on solar energy. Solar energy been harnessed with specialized equipment and used as an alternative source of energy, mainly because it is free and does not harm the environment.