The environmental impact of energy activities is regulated by a wide number of bilateral, regional, and multilateral treaties as well as customary rules providing for a variety of issues, ranging from procedural obligations to cooperate, consult and notify, to the regulation of the environmental impact of carbon-based energy production. The object of this course is to highlight the complexity of various energy and environmental issues and, to this end, two subjects will be explored: the first is a procedural requirement, namely the obligation to conduct Environmental Impact Assessment applicable to practically every energy activity, from access to energy resources to the conduct of energy activities. The second is the attempt to prevent, reduce, and control transboundary air pollution which also bears on many energy activities proved to contribute to air pollution.