The energy supply security pyramid: A quantitative framework for planning and policy making

Energy supply security (ESS) is one of the pillars of the Energy Trilemma. Although crucial for the transition to sustainable energy systems, ESS is frequently overlooked in energy system design. This article introduces the ESS Pyramid, a hierarchical framework combining conceptual insights with quantitative metrics to assess supply security. The ESS Pyramid has five levels, including foundational elements, such as Self-Production and Autonomy, and higher-order requirements, such as System Adequacy, Self-Sufficiency, and Autarky. Specific metrics are defined for each level to facilitate quantitative assessments that can inform strategic planning and policy-making. Using Switzerland's energy transition as a case study, we demonstrate the practical application of the ESS Pyramid and how sustainable transitions can also increase energy supply security. This framework provides policymakers, energy planners, analysts, and researchers with a structured approach that complements the already detailed approaches to Sustainability and Equity, the other two pillars of the Energy Trilemma.