Carbon negative pyrolysis of PLA waste for clean hydrogen production: Techno-economic analysis and life cycle assessment

초록

Global demand for polylactic acid (PLA) is rising, yet current PLA waste (PLAW) management imposes environmental burdens and recovers limited value. This study proposes a hydrogen production pathway integrating CO<inf>2</inf>-assisted PLAW pyrolysis with natural gas steam methane reforming (SMR). Pyrolysis-derived syngas is fed to the water–gas shift reactor, increasing H<inf>2</inf> production by 60.1%. The optimized SMR + PLAW<inf>opt</inf> configuration utilizes PSA off-gas, pyrolysis oil combustion, and flue-gas waste heat, thereby reducing total energy consumption by 19.3% compared with conventional SMR. CO<inf>2</inf> emissions from the process are captured and stored via CCS. Techno-economic and life-cycle analyses show that SMR + PLAW<inf>opt</inf> reduces the levelized cost of hydrogen by 49.6% to 3.51 USD/kg H<inf>2</inf> and lowers global warming potential by 44.5% to 4.98 kg CO<inf>2</inf>/kg H<inf>2</inf>, enabling net-negative CO<inf>2</inf> emissions. By valorizing PLAW into syngas and coupling the system with CCS, resource recovery is enhanced and deep decarbonization goals for hydrogen supply are supported. © 2026

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