Energetic, exergetic and environmental life cycle assessment analyses as tools for optimization of hydrogen production by autothermal reforming of bioethanol

This paper proposes a methodology devoted to finding and selecting more accurate conditions for sustainable hydrogen production via autothermal reforming of bioethanol. This methodology implies entire hydrogen production process design and simulation, energetic, exergetic and environmental life cycle assessment analysis studies and parametric (intuitive and design of experiment based methods) investigations. A base-case process operating under conditions recommended by simple investigation of chemical reactions was thoroughly studied. The results show that this base case process suffers from low performance. This is because the energetic, exergetic and environmental performances are comparatively lower than similar findings previously reported by other researchers for other reformates. The parametric investigation indicates that the process performances could be ensured by a proper and rational combination of the reactor temperature and the steam-to-carbon ratio. A key outcome of this research lies in establishing of second order mathematical models. These models can rapidly estimate the process performances (energetic, exergetic and environmental) based on temperature and the steam-to-carbon ratio. This paper recommends a reforming a temperature of 800 degrees C and a steam-to-carbon ratio of 4 as the most accurate conditions for autothermal reforming of bioethanol. Such conditions ensure not only the lowest consumption of energy to generate a given amount of hydrogen but also the best environmental performance of the entire system. (C) 2016 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.