Measuring energy security during the energy transition: Development of a composite energy security index and evidence from Vietnam

In many developing countries, the energy transition has brought different stakeholders into the same discussion, but they do not always view the issue the same way. Energy experts are concerned with reliability, system adequacy, reserve margins, and grid operation. Environmental groups mainly look at emissions and renewable energy deployment. Other issues, such as electricity prices, investment needs, energy access, and social impacts, are often discussed less consistently. This creates a practical problem for policymakers: the same policy may be seen as progress by one group, but as a new risk by another. This paper addresses two research questions. First, can a multidimensional Energy Security Index help policymakers identify trade-offs between decarbonization, affordability, reliability, resilience, governance, and social outcomes during the energy transition? Second, how can such a framework be used to assess the effects of energy transition policies on energy security in developing countries? This paper proposes a different way of assessing energy transition by using a Composite Energy Security Index as an integrated analytical framework. The proposed approach moves beyond measuring transition solely through renewable energy capacity or carbon emissions. It looks at whether progress is being made while maintaining supply security, affordability, environmental sustainability, system resilience, and effective governance. The index is built from selected indicators, with weights informed by expert consultation, followed by min–max normalization and annual aggregation. Vietnam is used as a testing case for this approach. The analysis looks at five areas: supply security, affordability, environmental performance, system resilience, and governance. When this approach is applied to Vietnam for the period 2007–2023, the results do not show a simple story of steady progress. The overall index increased over time, driven by improved electricity access, greater supply availability, and a more diversified energy mix. At the same time, some weaknesses became more visible in the later years. Since around 2020, the resilience dimension has declined, consistent with the challenges of integrating large amounts of solar and wind power into a grid not designed for such rapid change. The environmental dimension also remained unstable, which suggests that adding renewable capacity is only one part of a broader sustainability transition. The paper argues that energy transition should be assessed not only by the speed of renewable energy deployment or emissions reduction, but also by whether it maintains affordability, reliability, resilience, governance capacity, and social legitimacy. By bringing different stakeholder concerns into a common evidence base, the ESI can serve not only as a measurement tool, but also as a practical governance framework for a more balanced energy transition dialogue. The methodology is now being extended to five ASEAN countries to support regional comparison and policy learning on energy security during the energy transition.