Thermodynamic Assessment of a Cogeneration System Based on Aluminium–Water Reaction for Hydrogen and Power Production

This paper presents a conceptual and thermodynamic assessment of an innovative cogeneration system based on the aluminium–water reaction, designed to simultaneously produce hydrogen and electricity. The proposed layout integrates a liquid aluminium combustion chamber with a dual-stage heat recovery section and a steam turbine cycle, enabling the valorisation of industrial aluminium scraps within a circular-economy framework. A steady-state thermodynamic model was developed in Aspen Plus to evaluate system performance under different operating conditions, with a sensitivity analysis on key parameters such as the aluminium-to-water ratio (2.4–4), combustion efficiency, and steam generation cycle parameters. The system performance is investigated in terms of useful output (i.e., hydrogen and electricity production), including a simplified economic evaluation for the assessment of sustainability. Results indicate that, for equivalence ratios ensuring acceptable peak temperatures (≤1700 ◦C), the system can deliver 2–3 MW of electric power per kg/s of aluminium and achieve cogeneration efficiencies up to 83–87%, assuming a high conversion rate of water into hydrogen (roughly 0.106 kg of produced H2 per kg of inlet Al, if 95% of mole conversion is considered). The minimum break-even levelized cost of hydrogen is estimated to be 15.7 EUR/kg under current economic conditions.