Comparative Evaluation of Energy Recovery Systems for Enhanced Automotive Overall Efficiency

The rapid growth of the global automotive industry has led to increased fuel consumption and significant environmental challenges, particularly in the form of CO emissions. Energy recovery systems (ERSs) offer a promising solution to improve vehicle efficiency and reduce environmental impact. This paper evaluates five prominent energy recovery methods: regenerative braking, mechanical flywheel, thermoelectric recovery, Rankine cycle, and electric turbocharger, to determine their effectiveness in reducing fuel consumption and enhancing energy efficiency. Through a comprehensive review of experimental and simulation-based studies, each method is analyzed under various driving conditions, including urban, highway, and other cycles. Results indicate that the Rankine cycle achieves the highest theoretical efficiency (peak 23.7%, average 5.50%) under stable high-speed conditions, while regenerative braking excels in urban settings with frequent deceleration (38.854.2% recovery efficiency). Mechanical flywheels show strong performance in high-power transients (up to 39% fuel savings), whereas thermoelectric and electric turbocharger systems provide more modest gains. The study concludes that the optimal energy recovery strategy is highly dependent on specific driving conditions, and selection of the most appropriate technology should be based on the predominant operational profile of the vehicle.