Green Energy is increasingly becoming an important component for all individuals and governments of the world. According to Brundtland Commission Report (Our Common Future, 1987) of United Nations states: sustainable development is development that meets the needs of the present without compromising the ability of future generations to meet their own needs. Green Energy is widely considered as Sustainable Energy/ Re-newable Energy which meets the needs of the present without compromising the ability of future generation to meet their own needs. In the global movement of Green Energy Sustainable Renewable Energy, most of the countries decided to be a part of this movement of saving our planet and our future generation. This effort is supported by eleven international authors who are experts in their respective fields. The output is this book Green Energy. This book is comprises of six chapters.The first chapter discusses how global temperature can be controlled with the help of technology. Second chapter explains about green buildings. It explains about costs and benefits of green houses. Third chapter discusses about biofuels. Fourth chapter discusses about technical feasibility of Renewable Electricity Generation in Nunavut. Fifth chapter presents a summary of 15 years of grass root project experience in Partnership with impoverished, remote high altitude communities in the Nepal Himalayas. Sixth chapter argues that, contrary to popular belief, sustainable sources, in particular solar power, are capable of providing allthe energy the Europe needs at reasonable cost.