A comprehensive review of algal biodiesel for compression ignition engines: Challenges,advances,and future prospects

Abstract

Biodiesel derived from microalgae and macroalgae, as a third-generation biofuel, presents a sustainable and renewable alternative for use in conventional diesel engines with minimal to no modifications. Despite extensive research available on algal biodiesel, there is a significant lack of progressive reviews specifically addressing its utilization in diesel engines, along with the influence of key operating parameters such as load, speed, injection pressure, injection timing, and compression ratio. This review aims to bridge this gap by investigating the physicochemical properties of algal biodiesel, along with its storage, transport, blending potential and compliance with emission norms. The study further analyzes combustion, performance, and emissions characteristics of algal biodiesel blends ranging from B10 to B100, identifying B20 as the most optimal blend due to its diesel-like combustion and performance characteristics and lower exhaust emissions under various engine conditions. For B20 blends, variations in peak in-cylinder pressure, maximum heat release rate, brake thermal efficiency, brake-specific fuel consumption, and exhaust gas temperature ranged from 0.9% to 6.5%, while oxides of nitrogen, carbon monoxide, hydrocarbons, and carbon dioxide emissions differed by 2.5–13% compared to diesel. The findings are backed by experimental validation, including uncertainty analysis to ensure the reliability and accuracy of the mentioned data. However, higher blend ratios tend to negatively impact engine combustion and performance while also increasing NOx emissions. To counteract these challenges, this review examines the role of fuel additives, advanced combustion strategies, and commercialization barriers, highlighting algal biodiesel's technical and environmental promise as a sustainable and efficient alternative fuel.