Volume 28: Closing Carbon Cycles – A Transformation Process Involving Technology, Economy, and Society: Part III

Is bioethanol worth the energy? An energy metrics’ perspective Gabriela Steenekamp, Dr Ryan Merckel

Abstract

Typical industrial-scale sugarcane-to-bioethanol processes are evaluated using exergy and mass-based metrics. A more robust set of energy metrics, the change in energy quality and energy yield, are applied to assess the life-cycle efficiency of sugarcane upgradation. From an energy perspective, bioethanol production is not justifiable. Bioethanol achieves a poor energy recovery from sugarcane. Sugarcane to bioethanol, and subsequent electricity/power production, results in considerable energy losses even when compared to combusting the sugarcane itself. A technoeconomic feasibility study would be required to justify the 3 % gain in energy yield achieved when incorporating 2G processes into existing 1G infrastructure.

Keywords Bioethanol, sugarcane, energy metrics, energy quality, energy yield