Thermodynamic analysis of models used in hydrogen production by geothermal energy

Four models are developed for the use of geothermal energy for hydrogen production. These include using geothermal work output as the work input for an electrolysis process (Case 1); using part of geothermal heat to produce work for electrolysis process and part of geothermal heat in an electrolysis process to preheat the water (Case 2), using geothermal heat to preheat water in a high-temperature electrolysis process (Case 3), and using part of geothermal work for electrolysis and the remaining part for liquefaction (Case 4). These models are studied thermodynamically, and both reversible and actual (irreversible) operation of the models are considered. The effect of geothermal water temperature on the amount of hydrogen production per unit mass of geothermal water is investigated for all four models, and the results are compared. The results show that as the temperature of geothermal water increases the amount of hydrogen production increases. Also, 1.34 g of hydrogen may be produced by one kg of geothermal water at 200 °C in the reversible operation for Case 1. The corresponding values are 1.42, 1.91, and 1.22 in Case 2, Case 3, and Case 4, respectively. Greater amounts of hydrogen may be produced in Case 3 compared to other cases. Case 2 performs better than Case 1 because of the enhanced use of geothermal resource in the process. Case 4 allows both hydrogen production and liquefaction using the same geothermal resource, and provides a good solution for the remote geothermal resources. A comparison of hydrogen production values in the reversible and irreversible conditions reveal that the second-law efficiencies of the models are 28.5%, 29.9%, 37.2%, and 16.1% in Case 1, Case 2, Case 3, and Case 4, respectively.

[1]  M. Balat,et al.  Political, economic and environmental impacts of biomass-based hydrogen , 2009 .

[2]  Mehmet Kanoglu,et al.  Improving the performance of an existing air-cooled binary geothermal power plant : A case study , 1999 .

[3]  Enrico Gobbetti,et al.  Encyclopedia of Electrical and Electronics Engineering , 1999 .

[4]  A. Hepbasli,et al.  Thermodynamic assessment of geothermal energy use in hydrogen production , 2009 .

[5]  Mehmet Kanoglu,et al.  Exergy analysis of a dual-level binary geothermal power plant , 2002 .

[6]  P. N. Sarma,et al.  Simultaneous biohydrogen production and wastewater treatment in biofilm configured anaerobic periodic discontinuous batch reactor using distillery wastewater , 2008 .

[7]  Ibrahim Dincer,et al.  Geothermal energy use in hydrogen liquefaction , 2007 .

[8]  C. Mansilla,et al.  Can high temperature steam electrolysis function with geothermal heat , 2007 .

[9]  Y. Çengel,et al.  Thermodynamics : An Engineering Approach , 1989 .

[10]  Tomasz Wiltowski,et al.  Catalyst development for thermocatalytic decomposition of methane to hydrogen , 2008 .

[11]  E. Barbier.  Nature and technology of geothermal energy: A review , 1997 .

[12]  Ibrahim Dincer,et al.  Parametric Study of the Effect of Reference State on Energy and Exergy Efficiencies of Geothermal District Heating Systems (GDHSs): An Application of the Salihli GDHS in Turkey , 2007 .

[13]  Andrew E. Lutz,et al.  Exergy analysis of hydrogen production via steam methane reforming , 2007 .

[14]  H. Ingason,et al.  Optimizing site selection for hydrogen production in Iceland , 2008 .

[15]  André Bontemps,et al.  Heat management for hydrogen production by high temperature steam electrolysis , 2007 .

[16]  S. A. Sherif,et al.  An economic analysis of three hydrogen liquefaction systems , 1998 .

[17]  J. E. O’Brien,et al.  THERMODYNAMIC CONSIDERATIONS FOR THERMAL WATER SPLITTING PROCESSES AND HIGH TEMPERATURE ELECTROLYSIS , 2008 .

[18]  Ibrahim Dincer,et al.  Potential methods for geothermal-based hydrogen production , 2010 .

[19]  Thorsteinn I. Sigfusson,et al.  The feasibility of using geothermal energy in hydrogen production , 1992 .