Primary energy has the potential to bring challenges to the reliability, economic, and eco-friendliness of global electric power systems. The concept of electric power security are proposed, including many factors that are not considered in power system reliability analysis, such as coal supply for power system, fuel price for electricity power market, carbon emissions of power generation, and so on. It is broader than power system reliability and security, which means that providing energy in

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... he form of reliable, economical, and eco-friendly electric power. Following an account of existing blackout defence methods and systems, the processes of transforming various kinds of primary energy into electric power and the interactions between them are described, particularly with regard to flows of energy, capital, and information. Factors that limit the liquidity of these flows are defined as "generalized congestion", and the challenges presented by primary energy are named "primary energy congestion". China's dilemma on coal supply for power generation is presented in some detail as an example of primary energy congestion. To cope with impacts of the primary energy on electric power systems, an idea is introduced to extend the scope of existing coordinated blackout defence systems to account for primary energy, which would lead to an integrated tool to provide decision support to power system operators accounting for primary energy congestion.