Alternate fuels for internal combustion engines: Status review on improving performance and reducing emissions with biodiesel, bio‐alcohol, bio‐oil and plastic oil

Due to fossil fuel depletion and environmental concerns, alternative fuels such as biodiesel, bio alcohols, bio‐oil, and plastic oil are being investigated for internal combustion engines (ICEs), providing a way to lower emissions and increase energy security. While these oxygenated biofuels reduce particulate matter, carbon monoxide, and unburned hydrocarbons, they may increase nitrogen oxide emissions, and pure biofuels may produce somewhat less power than traditional diesel. While many studies have already reported on any one type of these fuels, the comparison between them is lacking. This article includes an in‐depth assessment of current research on the usage of biodiesel, bio‐alcohol, bio‐oil, and plastic oil as well as their characteristics, internal combustion engine (ICE) performance, and emissions. The review discusses the sort of engines powered by these fuels, their density, ignition quality (cetane/octane), viscosity and stability, engine performance, engine emissions, and finally their suitability and challenges. This comprehensive review also highlighted the future focus on the importance of fuel optimization through improved engine control, dual‐fuel concepts, and additive integration, as well as the development of next‐generation biofuels for sustainability.