In our environmentally concerned society, hydrogen is becoming one of the most important future energy carriers. Hydrogen combustion produces no CO2 emission, and energy conversion technique based on hydrogen technologies penetrates more and more in our daily life. Many firms and users consider new systems and application areas. In order to successfully start new applications, it is necessary to have basic knowledge on the technologies, engineering, legislatives, and cost calculations in this emerging field. Though many books have been issued, and some examples are presented, still discussion on details is missing. Additionally, many norms, regulations, and standards are permanently changing, and some overviews are also needed. In the last 20 years, many practical solutions have been successfully developed and tested. One of the best ways to learn about single components or whole systems and, in some cases also on safety, is to discuss designs of previous projects, which were successfully realized. Such a practical approach was not considered in the previous literature sources and, therefore, this book is intended to supplement the available information, which is presented in opening literature sources. This book will be helpful for engineers working with energy conversion techniques and hydrogen technologies as well as for graduate students.