Thermodynamic analysis of bioethanol production from wheat straw

The thermodynamic implications of different bioethanol production routes from wheat straw (a cellulosic co-product or 'waste' stream) have been evaluated. Thermodynamic (energy and exergy) analysis gives rise to alternative insights into the relative performance of various process chains. The thermodynamic property known as 'exergy', for example, reflects the ability of undertake 'useful work', but does not represent well heating processes. Thus, energy analysis of four different production paths have been analysed via the consideration of mechanical work, temperature changes and separating techniques. The Net Energy Value (NEV) of each production path or route was then evaluated, including the effect of system boundary expansion. Exergetic efficiencies were be obtained through chemical and physical exergy calculations, along with some of the electrical inputs to the different processes. Improvement potentials of the process stages were then determined using the exergetic efficiencies and irreversibility values respectively. These estimates will enable industrialists and policy makers to take account of some of the consequences of alternative bioethanol production routes in a low carbon future.