Investment valuation model for sustainable infrastructure systems: Mezzanine debt for water projects

Purpose: The purpose of this paper is to develop an investment valuation model using the mezzanine debt mechanism based on blue bonds that explicitly allude to public–private partnerships (P3s) and project finance (PF). Additionally, this study proposes the financial captured value (FCV) theory for measuring how much financial value lenders may capture by becoming sponsors through financing of sustainable infrastructure systems (SIS). Design/methodology/approach: The investment valuation model was validated through the Aguas Claras wastewater treatment plant as a case study. Findings: The empirical results show that lenders may capture financial value by converting outstanding debt into equity shares throughout the operation and maintenance stage. Furthermore, case study results provide new insights into the implications of the debt–equity conversion ratio on the relationship between the sponsors' internal rate of return and the FCV. Research limitations/implications: The most significant limitation is the lack of primary and secondary information on blue bonds. Thus, robust statistical analyses to contrast results were not possible. Practical implications: Researchers and practising professionals can improve their understanding of how mezzanine debt, P3s and PF into an investment valuation model allows financing SIS using a non-conventional financial mechanism. The recommendations will benefit both the academia as well infrastructure industry in bridging the gap between design theory and practice. Originality/value: Sustainability components have not been addressed explicitly or combined in the financing’s structuring. Therefore, the investment valuation model could be considered a novel methodology for decision making related to financing and investment of SIS.