Digital Twin for Hydrogen Production from Waste Biomass: A Comprehensive Framework for Design, Optimization, and Control

Abstract This paper presents a digital twin (DT) framework for the design, optimization, and real-time control of a pilot-scale hydrogen (H2) production system based on the thermochemical gasification of waste biomass. The pilot-scale system has a nominal maximum H2 production rate of 45 kg/day. It comprises of a downdraft gasifier; a reactive and adsorption system (RAS), consisting of a water gas shift (WGS) reactor and a multistage adsorption-based purification system for impurity removal, and a pressure swing adsorption (PSA) unit to produce high-purity H2. The DT model, implemented in MATLAB and DO-MORE software, serves as a virtual replica of the physical plant. Its use allowed the design and construction of the pilot-scale system based solely on lab-scale-generated catalytic reaction kinetics and adsorption-based purification studies. Model validation was conducted in Phase I of the project employing synthetic syngas mixtures representative of oxygen/steam-blown gasification conditions at a feed flow rate of 10 SCFM and a H2 production rate of ∼21 kg/day. The DT demonstrated good accuracy in predicting system temperatures (RMSE = 13.82 °C, MAE = 11.3 °C, MAPE = 2.9%) and gas compositions and conversion (RMSE = 1.7%, MAE = 1.71%, MAPE = 2.1%), confirming its reliable representation of reaction kinetics and mass and energy balances. The DT incorporates methodologies that allow for real-time process monitoring, enabling the real-time optimization of heating and liquid flows within the pilot plant, resulting in better thermal management and reduction in utility costs across the RAS system. In Phase II of the project, we will extend this control architecture through the integration of steam and gas flow controllers, thus achieving complete closed-loop control of the system. The system will be operated with real syngas from the gasifier at its maximum operating capacity of 25 SCFM, corresponding to a H2 production output of 45 kg/day. Techno-economic analysis estimates the levelized cost of hydrogen (LCOH), over a 20 year plant life, operating at such capacity, and a 7% discount rate to be \$2.33/kg. These results establish a scalable and economically viable pathway for waste-to-hydrogen production and future commercialization, validating the impact of a DT to enhance process economics at scale.