Bioethanol, internal combustion engines and the development of zero-waste biorefineries: an approach towards sustainable motor spirit

Nature is a huge reservoir of energy, aiding the proliferation of life on Earth. However, recently, the human race has understood the importance of conserving the energy sources that are available in nature and prone to depletion. Lately, it has been well understood that either the use of fossil fuels should be restricted or the potential of other energy sources should be explored. In this context, the concept of biofuel has emerged, which in its neat form or as a blend with petroleum products can achieve the above-mentioned goals. In this review, we depict the potential of bioethanol as a future transportation fuel. Furthermore, the compatibility, advantages, and shortcomings of bioethanol as a fuel for internal combustion engines are also discussed. Studies revealed that blending ethanol in petrol or Motor Spirit (MS) improves important engine features such as octane number (up to 5-10%), compression ratio (up to 2%), combustion efficiency (up to 30%), and engine torque (up to 8%). The use of biofuel is also considered significantly beneficial to the environment in terms of the emission of greenhouse gases. This aspect of bioethanol is also briefly presented in this review. The possibility of the large-scale production of bioethanol has attracted global interest, and consequently, the concept of a 'biorefinery' has been proposed recently. The development of biorefineries with a 'zero-waste' approach is an important aspect for the future global energy demand as well as the environment. The overall goal of this review is to analyze the potential of bioethanol as a sustainable Motor Spirit in the near future. This review article describes the generations of bioethanol and their sustainability. Furthermore, the compatibility of bioethanol blended fuels with motor engines is described. Also, approaches towards zero-waste biorefineries are highlighted.