Techno-economic Analysis and Life Cycle Impact Assessment for the Valorisation of Kraft Lignin and Low-Voltage Hydrogen Production

This study presents a comparative techno-economic analysis and life cycle impact assessment of hydrogen production from the kraft lignin depolymerization (KLD) with those produced from alkaline electrolysis cell (AEC) and proton exchange membrane electrolysis (PEM). This process happens in a continuous modular flow reactor by using the phosphomolybdic acid as a redox-active catalyst and includes depolymerizing the kraft lignin, producing vanillin, acetovanillone, and hydrogen under a low-voltage condition. For the techno-economic analysis, first, the processes were modelled by using the Aspen Plus V12.1 software and then the results were transferred to Aspen Process Economic Analyzer V12 for economic evaluation. In the next step, the life cycle impact assessment was proposed by using the openLCA V1.11.0 software along with the Environmental Footprint database (MID-Point indicator), and 18 impacts were investigated. According to the techno-economic analysis, KLD exhibits a total capital cost that surpasses that of AEC and PEM by more than 18% and 11%, respectively. Furthermore, KLD's equipment cost exceeds that of AEC and PEM by approximately 0.5% and 7%, respectively, and necessitates additional components. On the other hand, the life cycle assessment revealed that KLD yields lesser environmental impacts than AEC, while PEM exhibits the most exemplary environmental performance.