📝 SummarXiv

Abstract

Net energy - the energy obtained from a resource after accounting for the energy expended in its acquisition - fundamentally determines the capacity of societies to sustain and expand. The extended Energy Return on Investment (EROIext) incorporates not only extraction and refining but also transport and end-use infrastructure, yet its long-term dynamics remain poorly understood. Here, we apply a Single-Cycle Lotka-Volterra (SCLV) model to the global petroleum system, calibrated with historical data from 1965-2012. The model projects trajectories of production, capital, and EROIext to 2100, and integrates an entropy-based indicator to evaluate the system's ability to maintain social order. Results show that oil production peaks around 2041, while EROIext declines continuously and falls below unity by 2081. This marks the point at which oil no longer delivers net energy, coinciding with the peak of capital stock, suggesting unsustainable investment in a diminishing resource. The rising entropy ratio signals declining systemic resilience. These findings underscore the importance of evaluating energy systems not only by quantity or cost but also by thermodynamic quality, with direct implications for balancing short-term energy security and long-term sustainability in policy design.