Renewable energy technologies have been used on a small scale for many years. Issues of intermittency and cost have prevented their wide-spread use and acceptance. Now, discussion and research aims to move the current global fossil fuels economy to one based on hydrogen. This book presents an original and comprehensive approach to hybrid energy system optimization providing a much-needed systems approach to hydrogen energy applications, by discussing the fundamentals of renewable power generation, conversion and storage; presenting a unique system optimization approach to hybrid hydrogen energy system design that minimizes cost and maximizes reliability; introducing the benefits of hydrogen as an energy carrier in the context of sustainability. This book will be of value to graduates and senior undergraduates studying renewable energy and hydrogen energy systems as well as lecturers in these subjects. It will also interest researchers, practitioners and policy makers in these fields.