Acknowledgements

by hydrogen permeation membrane, which has showed a sharply enhanced conversion rate of 87.8% at 1500°C and 10<sup>5</sup> bar at permeated side (versus 1.26% with oxygen permeation membrane or isothermal thermochemical cycle). Recently, a promising method for hydrogen generation without carbon emitting by ammonia decomposition in a catalytic palladium membrane reactor for hydrogen separation driven by solar energy has been theoretically proposed, and the first-law thermodynamic efficiency, net solar-to-hydrogen efficiency, and exergy efficiency can

reach as high as 86.86, 40.08, and 72.07%, respectively [68].

Wind Solar Hybrid Renewable Energy System

high partial pressure and less separation energy required [71].

chemical fuel generation, and the highlighted conclusions are listed:

membrane, O<sup>2</sup>/CO3

5. Conclusions

has been obtained.

continuous operation.

156

4.4 Challenges and perspectives

4.3 Carbon dioxide permeation membrane for hydrocarbon reforming

<sup>2</sup> conducting membrane, OH/CO3

Though the solar membrane reactor has lots of advantages and immense potential for application mentioned above, the efficient approach to lower the partial pressure of gas product (or avoid the relatively low pressure) is the main challenge to maintain a high energy conversion rate, and the improvement of stability and permeability of membrane material at corresponding reaction temperature is also significant. These issues have potential areas for big breakthroughs and require further studies to address. The multiple product separation with membrane reactor may be a promising method to increase the energy efficiency, due to a relatively

This chapter has reviewed the state-of-the-art researches about solar thermo-

a. The thermodynamics in solar thermochemical fuel generation has been

b. The most representative solar thermochemical reactions (e.g., H2O/CO2 splitting, hydrocarbon reforming, and decomposition) have been reviewed, and the advantages and drawbacks have been analyzed and discussed.

c. Thermochemical cycle and membrane reactor driven by solar energy have been systematically introduced, which could decrease the reaction temperature and have the potential to be widely utilized in the future, especially the membrane reactor, which could purify the product with a

analyzed, and the maximum theoretical efficiency from solar energy to work

(hydroxide/ceramic dual-phase membrane), etc. [69, 70]. The combination between carbon dioxide permeation membrane and solar energy is very limited now. The combination of hydrogen permeation membrane and carbon dioxide permeation membrane has been proposed for methane steam reforming by way of an alternate H2 and CO2 separation driven by solar energy [71]. The carbon dioxide permeation membrane has great potential to be utilized for the hydrocarbon reforming or decomposition for CO2 separation and capture in the future.

<sup>2</sup> conducting

<sup>2</sup> conducting membrane

Carbon dioxide permeation membrane includes mixed e/CO3

This work is funded by the National Natural Science Foundation of China (no. 51906179) and the State Scholarship Fund (No. 201906275035) from China Scholarship Council.
