Electric versus ethanol? A fleet-based well-to-wheel system dynamic model for passenger vehicles

Dynamic models are routinely used in the development of sustainable transportation systems. Yet, policymakers question the reliability of the estimates they produce. More holistic models that include a dynamic well-to-wheel system perspective, built-in sensitivity tests, and ask ‘what if’ policy questions can potentially improve the robustness of the estimates. Accordingly, we develop a system dynamics, fleet-based, life cycle model that offers these features and apply it to Brazil’s electric-vs-ethanol debate. We present the results through different scenarios, from business-as-usual to more extreme dependence on particular energy sources. Amongst other things, they show that ethanol dominates in most scenarios except under certain long term land use assumptions that heighten well-to-tank emissions. They also highlight the sensitivity of LCA results to underlying assumptions and encourage the standardisation of reporting norms. Finally, our model highlight where ambiguities are likely to materialise, providing useful insights to practitioners in Brazil and elsewhere.