Thermodynamic investigation and comparison of selected production processes for hydrogen and hydrogen-derived fuels

The results are reported of comparisons based on energy and exergy analyses of a wide range of production processes for hydrogen and hydrogen-derived fuels (HDFs). A commercial process-simulation computer code, previously enhanced by the author for exergy analysis, is used in the analyses. Depending on the process and the efficiency definition used, overall efficiencies are determined to range widely, from 21 to 92% for energy efficiencies and from 19 to 83% for exergy efficiencies. The losses for 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 4 to 11% 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 the improvement of existing and design of future production processes for hydrogen and HDFs. Copyright (C) 1996 Elsevier Science Ltd.