In recent decades, many kinds of research have been conducted on alternative fuels for compression ignition (CI) engines. Low/zero-carbon fuels, such as bioalcohols and hydrogen, are the most promising alternative fuels and are extensively studied because of their availability, ease of manufacturing, and environmental benefits. Using these promising fuels in CI engines is environmentally and economically beneficial. The most common alcohols are methanol, ethanol, isopropanol, propanol, butanol, n-butanol, tert-butanol, iso-butanol, and pentanol. The primary objective of this review paper is to examine the impact of bioalcohols and their blends with conventional diesel fuel in CI engines since these fuels possess characteristic properties that impact overall engine performance and exhaust emissions. This research also indicated that alcohols and blended fuels could be used as fuels in compression ignition engines. Chemical and physical properties of alcohols were examined, such as lubricity, viscosity, calorific value, and cetane number, and their combustion characteristics in compression ignition engines provide a comprehensive review of their potential biofuels as alternative fuels.

Renewable sources include plants and animal fats, which are the main components of biofuels. Biofuels are free from sulfur, aromatics, metals, and crude oil residues. Since biofuels are more lubricating than petroleum diesel fuel, they are nonflammable and extend the life of diesel engines. As a result of this study, the main chemical and physical properties of biofuels were investigated, including their lubricity, viscosity, calorific value, and cetane number, which indicate the quality of renewable fuels, and compared with the other. We examined and compared the combustion characteristics of various types of biofuels as an alternative fuel, as well as their emissions characteristics. Biodiesel and biodiesel blends are compared to mineral diesel, as well as their performance in CI engines in this study’s review. With modified combustion equipment, biodiesel fuels can potentially reduce air pollution in diesel engines and are a very good substitute for fossil fuels. There is a need for more research and technological development in order for biofuels to become economically viable. Biofuel/biodiesel research should therefore be supported with policies that make their prices competitive with other conventional sources of energy. In the current state of affairs, biofuels are more effective when used alongside other sources of energy.