Enhancing efficiency of ethanol-powered range extenders in the BMW i3: A simulation-based optimization approach

Abstract

© 2025Ethanol-powered range-extended plug-in hybrid electric vehicles offer a sustainable alternative to reduce carbon emissions in light-duty transport. This study optimizes a BMW i3's range-extender engine for hydrous ethanol by increasing compression ratio, applying a Miller cycle, and using exhaust gas recirculation. Vehicle simulations and testing show a brake-specific fuel consumption reduction of up to 10.5 %, with a 4 % fuel efficiency gain over gasoline blends. Ethanol use decreased vehicle fuel consumption by over 20 % in most cycles and reduced overall energy consumption by 10 % compared to the gasoline range extender, though with a 5 % range loss due to ethanol's lower energy density. Despite this, ethanol's rapid refuelling capability presents an advantage over battery-electric vehicles. These findings highlight ethanol-powered range extenders as a practical solution to lower emissions while mitigating range anxiety.

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