Hydrogen production from fishing net waste for sustainable clean fuel: Techno-economic analysis and life cycle assessment

[Display omitted] •FNW CO2-based pyrolysis is integrated with the SMR to produce clean hydrogen.•The hydrogen production yield was increased by pyrolysis of FNW under CO2.•The process was operated without external energy supply through energy optimization.•An environmental impact analysis was conducted for hydrogen production using FNW. Fishing net waste (FNW) represents more than half of marine debris, posing a substantial challenge to marine ecosystems. Conventional disposal methods, such as landfills and incineration, contribute to environmental pollution and overlook valuable material recovery. To address this issue, an innovative process that converts FNWs into high-purity hydrogen (H2) through pyrolysis under CO2 conditions, integrated with a natural gas (NG) reforming process, was proposed. The resulting gas undergoes a water–gas shift (WGS) reaction with NG-reforming syngas, amplifying H2 production yield. High-purity H2 is achieved through pressure swing adsorption (PSA). The high-temperature flue gas from pyrolysis oil combustion is utilized to generate electricity via the steam Rankine cycle (SRC) process. Furthermore, CO2 in the flue gas is liquefied and stored through a carbon capture and storage (CCS) process. Techno-economic evaluation and life-cycle assessment (LCA) were performed to scrutinize the efficiency and feasibility of the proposed process. This study first demonstrated that the CO2-based waste fishing net pyrolysis integrated H2 production process yielded 10.66 kmol h−1 of H2, providing a significant step toward sustainable H2 production. Second, 87.13 % of wasted energy was recovered through the thermal integrated energy optimization of the waste fishing net and NG reforming process, and an additional 539.1 kW of electricity was generated through the SRC process, demonstrating high energy efficiency. Finally, although the levelized cost of hydrogen (LCOH) was slightly greater than that of the steam methane reforming (SMR) process, LCA revealed a significantly low greenhouse gas (GHG) index. Therefore, the proposed process serves as an eco-friendly approach to increase hydrogen production yield, which is a clean raw material with no carbon emissions, concurrently addressing the recycling of FNWs.