Hydrogen production by waste heat recovery of hydrogen-enriched compressed natural gas via steam methane reforming process

Hydrogen production is essential for clean energy technologies, particularly transportation but high energy demands and inefficiencies limit traditional methods. This study presents an approach to improving hydrogen production efficiency through the steam methane reforming (SMR) process, utilizing exhaust heat from a stoichiometric CNG-fueled spark ignition engine under conditions of 20 % hydrogen fraction, 20 % EGR ratio, 75 % engine load, and 1200 rpm engine speed. Two scenarios were simulated using ASPEN Plus (R), with a maximum heat utilization of 13 % in Case-1 and 58 % in Case-2. The maximum hydrogen production rate reached 6.72 kg/ h, with steam at 873 K and reformer conditions of 973 K and 1 bar. Engine efficiency was 36.44 %, with overall efficiencies of 62.23 % in Case-1 and 69.33 % in Case-2. Economic analysis showed a hydrogen production cost of $1.70/kg, close to the market price of $1.45/kg, demonstrating feasibility but indicating that subsidies are needed for competitiveness and practical applications.