scholarly journals Theoretical Thermodynamic Efficiency Limit of Isothermal Solar Fuel Generation from H2O/CO2 Splitting in Membrane Reactors

Molecules ◽  
2021 ◽  
Vol 26 (22) ◽  
pp. 7047
Author(s):  
Hongsheng Wang ◽  
Hui Kong ◽  
Jian Wang ◽  
Mingkai Liu ◽  
Bosheng Su ◽  
...  
Keyword(s):  
Separation Efficiency ◽  
Membrane Reactors ◽  
Maximum Efficiency ◽  
Thermodynamic Efficiency ◽  
Solar Fuel ◽  
Low Oxygen ◽  
Lower Temperature ◽  
Isothermal Operation ◽  
Chemical Cycling ◽  
Solar Fuel Generation

Solar fuel generation from thermochemical H2O or CO2 splitting is a promising and attractive approach for harvesting fuel without CO2 emissions. Yet, low conversion and high reaction temperature restrict its application. One method of increasing conversion at a lower temperature is to implement oxygen permeable membranes (OPM) into a membrane reactor configuration. This allows for the selective separation of generated oxygen and causes a forward shift in the equilibrium of H2O or CO2 splitting reactions. In this research, solar-driven fuel production via H2O or CO2 splitting with an OPM reactor is modeled in isothermal operation, with an emphasis on the calculation of the theoretical thermodynamic efficiency of the system. In addition to the energy required for the high temperature of the reaction, the energy required for maintaining low oxygen permeate pressure for oxygen removal has a large influence on the overall thermodynamic efficiency. The theoretical first-law thermodynamic efficiency is calculated using separation exergy, an electrochemical O2 pump, and a vacuum pump, which shows a maximum efficiency of 63.8%, 61.7%, and 8.00% for H2O splitting, respectively, and 63.6%, 61.5%, and 16.7% for CO2 splitting, respectively, in a temperature range of 800 °C to 2000 °C. The theoretical second-law thermodynamic efficiency is 55.7% and 65.7% for both H2O splitting and CO2 splitting at 2000 °C. An efficient O2 separation method is extremely crucial to achieve high thermodynamic efficiency, especially in the separation efficiency range of 0–20% and in relatively low reaction temperatures. This research is also applicable in other isothermal H2O or CO2 splitting systems (e.g., chemical cycling) due to similar thermodynamics.

scholarly journals Light Harvesting Proteins for Solar Fuel Generation in Bioengineered Photoelectrochemical Cells

2014 ◽  
Vol 15 (4) ◽  
pp. 374-384 ◽  
Author(s):  
Julian Ihssen ◽  
Artur Braun ◽  
Greta Faccio ◽  
Krisztina Gajda-Schrantz ◽  
Linda Thöny-Meyer
Keyword(s):  
Light Harvesting ◽  
Photoelectrochemical Cells ◽  
Solar Fuel ◽  
Solar Fuel Generation

Multiplication of LNG Cold to Produce Refrigeration at 273 K

1975 ◽  
Vol 97 (3) ◽  
pp. 915-920
Author(s):  
G. Best Brown
Keyword(s):  
Enthalpy Of Mixing ◽  
Thermodynamic Efficiency ◽  
Multiplication Factor ◽  
Absorption Process ◽  
Lower Temperature ◽  
Absorption Refrigerator

It is becoming of great importance to develop processes which can utilize the “available cold” of LNG and thus recover the energy used for its liquefaction. It is possible to evaluate the amount of refrigeration that could be produced reversibly Q1, at a temperature T1, from the amount of cold available, Q2, at a lower temperature, T2, in an environment at T0. This is:Q1Q2≤T0−T2T0−T1·T1T2 For LNG it would be obtained that: Q1Q2≤13.5 Work is being done to develop cold multiplication cycles which would approach this ideal figure. Among the systems under development is an absorption process resembling a reversal of the well-known absorption refrigerator. An ethane-neoheptane system is presented for which the multiplication factor has been around 1.8 and the efficiency of around 17 percent. The irreversibilities of the cycle and the low enthalpy of mixing of hydrocarbons are the main reasons for the relatively low cold multiplication factor and thermodynamic efficiency.

Effect of O2 Partial Pressure on Post Annealed Ba2YCU3O7-δ Thin Films

1992 ◽  
Vol 275 ◽  
Author(s):  
Julia M. PhUlips ◽  
M. P. Siegal ◽  
S. Y. Hou ◽  
T. H. Tiefel ◽  
J. H. Marshall
Keyword(s):  
Partial Pressure ◽  
Film Growth ◽  
Epitaxial Films ◽  
Pinning Force ◽  
Low Oxygen ◽  
O2 Partial Pressure ◽  
Growth Method ◽  
Lower Temperature ◽  
The Relationship

ABSTRACTEpitaxial films of Ba2YCu3O7-δ (BYCO) as thin as 250 å A and with Jc's approaching those of the best in situ grown films can be formed by co-evaporating BaF2, Y, and Cu followed by a two-stage anneal. These results extend the work on films > 2000 Å thick by R. Feenstra et al. [J. Appl. Phys. 69, 6569 (1991)]. High quality films of these thicknesses become possible if low oxygen partial pressure [p(O2) = 4.3 Torr] is used during the high temperature portion cf the anneal (Ta). The BYCO melt line is the upper limit for Ta. The use of low p(O2) shifts the window for stable BYCO film growth to lower temperature, which allows the formation of smooth films with greater microstructural disorder than is found in films grown in p(O2) = 740 Torr at higher Ta. The best films annealed in p(O2)=4.3 Torr have Jc values a factor of four higher than do comparable films annealed in P2=740 Torr. The relationship between the T required to grow films with the strongest pinning force and p(O2) is log independent of growth method (in situ or situ) over a range of five orders of magnitude of P(O2).

A Mini-Review on Nanostructured g-C3N4 Photocatalysts for Solar Fuel Production

2021 ◽  
Vol 12 ◽  
Author(s):  
Maxwell Selase Akple ◽  
Gabriel Kwame Sipi Takyi
Keyword(s):  
Photocatalytic Performance ◽  
Electronic Band Structure ◽  
Future Research ◽  
Solar Fuel ◽  
Fuel Production ◽  
Electronic Band ◽  
Research Attention ◽  
Electron Hole Pair ◽  
Photocatalytic Material ◽  
Solar Fuel Generation

Graphitic carbon nitride (g-C3N4) is an important photocatalytic material that receives a lot of research attention globally. This is because of its favourable thermal and chemical stability as well as electronic band structure. However, the photocatalytic performance of the bulk g-C3N4 is limited by fast recombination of electron-hole pair and poor visible light-harvesting ability. Thus, different strategies, such as heterostructuring, nanotuning, doping, etc., have been adopted to overcome the aforementioned challenges to enhance the photocatalytic performance of g-C3N4. In recent times, various nanostructured g-C3N4 photocatalytic materials with various tuned morphologies have been designed and fabricated in literature for different photocatalytic activities. This mini-review summarized the progress development of nanostructured g-C3N4 photocatalysts with various tuned morphologies for solar fuel generation. The article briefly highlights the research status of various g-C3N4 with tuned morphologies and enhanced solar fuel generation abilities. Finally, a conclusion and future research were also suggested, opening up new areas on g-C3N4 photocatalysis.

The Middle Road Less Taken: Electronic-Structure-Inspired Design of Hybrid Photocatalytic Platforms for Solar Fuel Generation

2018 ◽  
Vol 52 (3) ◽  
pp. 645-655 ◽  
Author(s):  
Junsang Cho ◽  
Aaron Sheng ◽  
Nuwanthi Suwandaratne ◽  
Linda Wangoh ◽  
Justin L. Andrews ◽  
...  
Keyword(s):  
Electronic Structure ◽  
Solar Fuel ◽  
Solar Fuel Generation

Fe/Mn-based Perovskite-Type Oxides with Excellent Oxygen Permeability and Reduction Tolerance

2004 ◽  
Vol 835 ◽  
Author(s):  
Yasutake Teraoka ◽  
Hironobu Shimokawa ◽  
Hajime Kusaba ◽  
Kazunari Sasaki
Keyword(s):  
Partial Oxidation ◽  
Synthesis Gas ◽  
Oxygen Permeability ◽  
Membrane Reactors ◽  
Permeation Flux ◽  
Low Oxygen ◽  
Reducing Atmosphere ◽  
A Site ◽  
Perovskite Type ◽  
Perovskite Type Structure

ABSTRACTA family of Co-free, Fe/Mn-based perovskite-type oxides, (Sr, A')(Fe, Mn)O3-δ (A'=La, Ba, Ca), was synthesized, and their oxygen permeability and phase stability in reducing atmosphere were investigated. The substitution of Mn at B site caused the decrease in oxygen permeability. As for the effect of A-site substitution, prominent promotion was observed by the substitution of Ba for 30% of Sr, and Ba0.3Sr0.7FeO3-δ was found to be one of most excellent oxygen permeable materials with the permeation flux of 3.0 cm3(STP) cm−2 min−1 at 900 °C. Reduction tolerance was evaluated by TG measurements in a 5%H2/N2 stream up to 1000 °C. After the TG measurements, crystal structures of La-Sr-Co-Fe-O and Sr-Fe-(Mn)-O perovskites were decomposed or transformed into low oxygen permeable phases, but the perovskite-type structure of Ba-Sr-Fe-(Mn)-O survived. The Fe/Mn-based perovskites with high oxygen permeability and exceeding reduction tolerance could be used as stable membrane materials for membrane reactors catalyzing NO-CH4 reaction and the partial oxidation of CH4 into synthesis gas.

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