Environmental performance of multi- objective optimal energy management for fuel cell hybrid and plug-in hybrid urban buses

PEDRO MUÑOZ; MARCOS GAUDIANO; DAMIAN FERNANDEZ; GABRIEL CORREA PERELMUTER

Rio de Janeiro

Congreso; 22nd World Hydrogen Energy Conference; 2018

International Association for Hydrogen Energy

This work presents a method to compare energy efficiency and environmental performance of a fuel cell hybrid electric vehicle (FCHEV) urban passenger bus with a plug-in and non plug-in configurations. The optimal power flux distribution between the fuel cell system and the battery system (EMS) was computed to minimize a sustainability index generated with inputs from well to wheel (WTW) analyses.The WTW analysis, is an useful approach for evaluating gas emissions, energy efficiencies, among other important indicators, produced by various means of transport using energy vectors produced through different pathways. It can be broken down in two stages, well to tank (WTT) and tank to wheel (TTW). The WTT step was made for present and future (year 2030) scenarios using different assumptions for the years to come and obtaining various energy and environmental parameters. Additionally, the TTW analysis was performed using dynamic models of vehicles. Both stages are integrated in a well-to-wheel (WTW) stage where relevant indexes are drawn: total energy efficiency (TEE) and emission index (EI).In order to properly assess the different systems and scenarios; a weighted multiphysics indicator (Integrated Sustainability Index) valued between zero and one was proposed. This single-objective cost function can be viewed as a linear scalarization of a multi-objective function. The bus energy management system (EMS) was ,then, optimized using the multi-objective minimization problem based on the aforementioned indexes. The minimization of this cost function was carried out by a gradient-based method.This study intends to address with a more comprehensive approach the evaluation of the sustainability of the different buses studied taking into account the energy management, the impact on the environment, and allows to visualize the degree of conflict between the different indices when varying the EMS of the vehicles and the energy production pathways and technologies.