This thesis aims to provide an understanding of how the world’s leading players are moving toward a new era in which the energy transition through the decarbonisation of entire sectors is something that is finally foreseeable and affordable. This important role belongs to several characters, each one has equal relevance and is able to communicate and collaborate with other parties. In this way, governments, investors, financers, companies and customers can achieve the desired outcomes that bring revenues and welfare to everyone. From this starting point, the most recent energy and sustainable policies are illustrated to strengthen the targets set, with the responsibility and the wish to respect them.