The Clean Development Mechanism (CDM) was introduced in 1997 as part of the Kyoto Procotol. This mechanism is designed to allow industrialized countries to promote projects that reduce emissions in developing countries, and thereby to support the stabilization and reduction of greenhouse gas emissions worldwide. The generated certified emission reduction may be traded in emissions trading schemes in form emission reduction certificates (CERs) or may be used to improve a country’s own emission balance. CDM projects need to be approved and officially registered in order to ensure additionality of the project, that is, to ensure the project reduces emissions more than would have occurred in the absence of the project. For this purpose the United Nations Framework Convention on Climate Change (UNFCCC) has published guidelines and methodologies, which are checked and followed during the certification of a project.