International emission trading will be one of the most important tools in the effort to reduce greenhouse gas emissions in the atmosphere. The reason is clear: emission trading can bring impressive cost savings. While the private sector has embraced the concept and is well equipped to use it, implementation at the international level remains incomplete. This book offers a comprehensive review of international emission trading, from the “perfect” system envisaged in economic models to a more realistic view of how trading can actually work. It is based on market experiments and modelling undertaken by the International Energy Agency and other institutions. It takes an in-depth look at implications for the power-generation sector, and considers how developing countries could be included in a future trading regime. With this work, we move from the question of “whether” to trade to the more operational question: “how”.