Fuel-cell technologies for private vehicles in Brazil: Environmental mirage or prospective romance? A comparative life cycle assessment of PEMFC and SOFC light-duty vehicles

Abstract

Fuel cell vehicles (FCV) have been proclaimed as a zero-tailpipe emissions alternative for passenger transportation; however, their overall environmental performance must be evaluated on a per-case basis. Although the environmental impacts (EI) of FCV have been already described in the literature, there is no evidence of comprehensive life cycle assessment studies analyzing the Brazilian case and its unique features, such as, the availability of biogenic feedstocks for hydrogen production via steam reform, high share of renewables in the electricity mix and the a novel powertrain technology based on solid-oxide fuel cells (SOFC) which could run on bioethanol. The purpose of this study was to quantify the EIs of polymer-electrolyte fuel cell (PEMFC) vehicles when hydrogen is produced in Brazilian conditions for a current and a 2030 scenario. Additionally, we intended to quantify the EIs of a prospective SOFC vehicle. Considering the significant burden of hydrogen production, we further aimed to explore several pathways and feedstocks for production. We found that SOFC vehicles could become a competitive alternative for impact mitigation in 2030. Most significant impact reductions are not likely to arise from fuel cell weight reduction as its burden is low compared to other car components or fuel production. As for today, PEMFC vehicles would not be competitive for any evaluated impact category. In fact, for global warming potential (GWP), they perform as bad as gasoline-fueled conventional vehicles. Assuming a centralized hydrogen production scheme, the distribution infrastructure was not a large contributor on a per-km basis. Nevertheless, building an entire hydrogen production and distribution infrastructure could be avoided under the SOFC powertrain technology. The environmental modelling of the SOFC was bound to uncertainties due to the lack of data. For GWP, the current ICEV ethanol car is competitive even for 2030 technologies, assuming the land does not come from deforestation.

Keywords: Biofuels reform; Brazil; Fuel cell vehicles; Hydrogen; Life cycle assessment; Solid-oxide fuel cell.