This module introduces the fundamentals of energy from a systems viewpoint. It covers issues on energy demand, supply, resources and policies. These issues are looked into in a holistic manner taking into account the need to balance among three competing ends: energy security, economic competitiveness, and environmental sustainability, i.e. the energy trilemma. Relevant cases will be used to show the complexity of energy problems and the trade-offs involved. The module also deals with the latest global energy scene and future outlook, including issues of direct relevance to Singapore.