A comparison of the eco-efficiency of two production routes for methanol
To achieve sustainable development in the chemical industry, there is a need for methodologies to assess the eco-efficiency of alternative and novel technologies. The aim of this project was to use a case study to investigate the application of existing tools to assess eco-efficiency. The case study compared the conventional methanol production process with a novel route using a photo-electrochemical (PEC) reactor. The Exergy Analysis showed that the exergetic efficiency (for the production phase) of the PEC process was much lower than that of the conventional process. However, exergy from the sun is free and abundant, and in such processes there can be large exergy losses without direct environmental consequences. The Life Cycle Analysis revealed that the two process routes have a similar overall environmental impact. The impact is dominated by the production phase for the conventional process, but by the construction phase for the PEC process. To improve the PEC process, priority should in principle be given to optimising the materials of construction, rather than improving the exergetic efficiency as such. Nevertheless, insofar as the large size of the PEC reactor is related to its low exergetic efficiency, we can still conclude that it makes no sense to squander exergy, even free exergy. 15 refs.
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