Monetizing Environmental Footprints: Index Development and Application to a Solar-Powered Chemicals Self-Supplied Desalination Plant

The assessment of the environmental greenness in the process industry has been quantified by means of the development of an integrated index, i.e., Monetized Footprint Index (MFI), based on the compilation and the integration of land, water and carbon footprint indicators. The MFI has been applied to assess the case study of a seawater reverse osmosis desalination with an integrated electrodialysis with bipolar membranes brine treatment. The MFI enables the evaluation of environmental burdens related to the chosen functional unit based on a weighting procedure, which integers land, water, and CO₂ prices. It is neither a tool for the calculation of the production cost nor a sustainability analysis tool as it does not include social or economic indicators. Comparison between selected scenarios, based on the different sources of the requested electricity, grid mix (Spain and Israel, as examples), and photovoltaic solar energy (under a fixed solar irradiation), has been carried out. Maximum values of 0.30 €·m^-3 and minimum values of 0.11 €·m^-3 for the different scenarios have been obtained in the calculation of the MFI. Moreover, uncertainties in land, water and CO₂ prices have been analyzed under a Monte Carlo simulation. This study concludes that MFI, being based on well-known environmental footprint indicators, can simplify and support the decision-making process.