The Second Law Analyses are commonly used as post-design tools for evaluating the actual performance of the systems under study. However, recent studies [1–5] have shown promising advantages when using these analyses such as Exergy and Entropy Generation Minimization Analyses during the design stages.
It is of interest to study Bio-fuel production processes under this optics because the design procedure of such processes, as in many other, is done with an almost trail-and-error methodology. This is mainly because to the inherent multiplicity in the next features.
Large feedstock variety.
Many possible sub-products
Different process routes.
Large number of technology (equipment) options.
Different desired products.
During the design of any transformation process, when using Process Integration techniques, the energy and material targeting are no-cost based analyses that can determine, the minimum surplus and deficits of energy and material. For energy production processes it is of interest to determine the minimal exergy requirement, minimal exergy rejection (to the environment), maximal exergy transfer and minimal exergy destruction within the process. These quantities are recently named as the exergy targets and can be calculated and illustrated by using a novel exergy diagram [4,6].
This work presents an analysis of several plants for the production of bio-fuels with different feedstock composition.
 A. Aspelund, D.O. Berstad, T. Gundersen, An Extended Pinch Analysis and Design procedure utilizing pressure based exergy for subambient cooling, Appl. Therm. Eng. 27 (2007) 2633–2649. doi:10.1016/j.applthermaleng.2007.04.017.
 D. Marmolejo-Correa, T. Gundersen, A new graphical exergy targeting representation for processes operating above and below ambient temperature, in: I.D.L. Bogle, M. Fairweather (Eds.), Comput. Aided Chem. Eng., Elsevier B.V., London, 2012: pp. 557–561. doi:10.1016/B978-0-444-59519-5.50112-X.
 D. Marmolejo-Correa, T. Gundersen, Exergetic Temperatures for Exergy Targeting, in: AIChE Annu. Meet., 2011.
 D. Marmolejo-Correa, T. Gundersen, New Graphical Representation of Exergy Applied to Low Temperature Process Design, Ind. Eng. Chem. Res. 52 (2013) 7145–7156. doi:10.1021/ie302541e.
 D. Marmolejo-Correa, T. Gundersen, Evolutionary Design of an LNG Process using the ExPAnD Method and a new Graphical Representation of Exergy, in: AIChE Spring Meet., Houston, TX, USA, 2012.
 D. Marmolejo-Correa, T. Gundersen, A new procedure for the design of LNG processes by combining exergy and pinch analyses, in: 25th Int. Conf. Effic. Cost, Optim. Simul. Energy Convers. Syst. Process. ECOS 2012, Aabo Akademi University, 2012: pp. 24–39.
See more of this Group/Topical: Sustainable Engineering Forum