Identifying dealbreakers and robust policies for the energy transition amid unexpected events

Abstract Disruptions in energy imports, backlash in social acceptance, and novel technologies failing to develop are unexpected events that are often overlooked in energy planning, despite their ability to jeopardize the energy transition. Here, we explore the role of unexpected events and assess their impact on the energy transition pathway of a large-scale whole-energy system. First, we evaluate unexpected events assuming ‘perfect foresight,’ where the decision-maker is aware of the unexpected-event scenario from the start of the transition. This analysis allows us to identify dealbreakers, i.e. conditions that cause the transition to exceed cost or carbon limits. Then, we assess the unexpected-event scenarios under ‘limited foresight’ to evaluate the robustness of early-stage decisions when unexpected events arrive as a surprise, and the costs associated with managing them. Unlike the perfect-foresight benchmark, it reflects real decision-making conditions and helps policymakers identify which near-term policies reduce vulnerability to unexpected events and what cost penalties arise when early decisions are suboptimal. A case study for a national energy system demonstrates that the absence of carbon capture technologies and electrofuel imports in 2050 are the main dealbreakers, while accelerating the deployment of renewables is the most robust policy. Our findings help policymakers identify dealbreakers and implement targeted measures to address them. The method is adaptable to different regions and scalable to entire continents, enabling policymakers to understand the impact of regional disruptions on the broader energy transition and analyze the vulnerabilities of energy policies under varying modeling assumptions.