The book is designed to acquaint readers with the development and key principles of emerging environmental policy and legislation particularly in novel areas of renewable energy and clean energy, The book tackles renewable energy, nuclear energy, geothermal energy, wind energy, solar energy, waste residual energy, (land fill) residual biomass, blue economy in the sustainable use of ocean resources for economic growth, improved livelihoods, and jobs while preserving the health of the ocean and river eco system. This is important especially now that the ocean is starting to lose its memory. The book further looks, at the doctrines of rebus sic stantibus, which establishes permanent sovereignty over natural resources, it also focuses on Jus cogens as a right to expropriate, more so as an expression of their sovereignty in order to safe guard natural resources and therefore the need to engage pacta sunt Servanda ( whatever is carried out on our environment should be carried out in good faith) it also addresses measures to implement greenhouse gas emissions and the need to consider smart utilization of available limited resources through integrated energy systems, the utilization of waste energy systems, and the utilization of waste energy streams. The book also considers the main concepts of thermal and conventional energy systems through detailed systems description, analyses the methodologies, performance assessment, optimization and gives illustrative examples of case studies. The book further examines producing power and heat with cooling, freshwater, green fuels and other useful commodities designed to tackle rising greenhouse gas emissions in the atmosphere. There is no doubt that with worldwide energy demand increasing the consequences of meeting supply with current dependency on fossil fuels, investigating and developing sustainable alternatives to the conventional energy systems is a growing concern for global stakeholders hence the compulsory need to write read and harness this book. Be glad that you have not found this book but rather this book has found you and now it’s time to have rendezvous with the future and save mother nature.