Overview about energy recovery applied to combustion engine focused on biofuels

Abstract

Hybrid vehicles present promising application prospects, combining the tradition and autonomy of combustion engines with the reliability, efficiency, and environmental appeal of electrification. In Brazil, the eighth-largest vehicle producer globally, up to 70% of the fleet comprises flex-fuel vehicles (FFVs), capable of operating with gasoline E27 (27% anhydrous ethanol), hydrous ethanol E100, or any blend, representing a significant portion of the country’s transportation matrix. Energy recovery is an important strategy for power conservation and increasing the efficiency of hybrid vehicles that combine internal combustion engines (ICE) and electric engines with small-capacity batteries, commonly applied in low-level electrification. This paper proposes an overview of technologies for ICE energy recovery to improve hybrid FFVs efficiency, that should be the main strategy for comply new emission legislation in Brazil and others markets in the next years. It employs a two-step approach: a literature review followed by patent analysis. The discussion analyzes advance technologies for recovering ICE energy like turbocharger, hybridization, exhaust gas recirculation (EGR) and Homogeneous Charge Compression Ignition (HCCI), applied to FFV ICEs. The United States, China and Germany are the countries with the highest number of patents registered in all ICE sub-technologies analyzed. Turbocharging appears to be a well-developed technology while HCCI still has many challenges to be overcome before it can be offered commercially. Hybrid FFVs vehicles using biofuel only or blended with gasoline offer a swift response to the energy transition in the mobility sector towards 100% electrification powertrain and provide a quicky solution for countries like Brazil.

Graphical abstract