Introduction: Energy systems modelling for decision-making

The role that energy modelling plays in improving the evidence base underpinning policy decisions is being increasingly recognized and valued. The Energy Technology Systems Analysis Program is a unique network of energy modelling teams from all around the world, cooperating to establish, maintain and expand a consistent energy/economy/environment/engineering analytical capability mainly based on the MARKAL/TIMES family of models, under the aegis of the International Energy Agency. Energy systems models like MARKAL/TIMES models provide technology rich, least cost future energy systems pathways and have been used extensively to explore least cost options for transitioning to an energy secure system and a low carbon future. This chapter presents an overview of ETSAP’s history and objectives, introduces the main principles of energy system modelling and summarizes the different chapters of the book.