Comparative assessment of thermodynamic efficiencies and losses for natural gas-based production processes for hydrogen, ammonia and methanol

Results are reported of comparisons based on energy and exergy analyses of production processes for hydrogen, ammonia and methanol from natural gas. A version of the Aspen Plus process-simulation computer code, previously enhanced by the author for exergy analysis, is used in the analyses. Overall efficiencies are determined to range widely, from 40 to 86% for energy efficiencies, and from 41 to 78% for exergy efficiencies. The losses in all processes are found to exhibit many common factors. Energy losses associated with emissions account for 100% of the total energy losses, while exergy losses associated with emissions account for less than 10% of the total exergy losses. The remaining exergy losses are associated with internal consumptions. It is anticipated that the results will prove useful to those involved in decision-making regarding alternative uses for natural gas.