Thermal Energy Storage Using the Boudouard Reaction

C + CO₂ ↔ 2CO (ΔH = 171 kJ/mol)

Depending on the operational needs, the energy storage reaction may be conducted to optimize performance at temperatures ranging between ca. 900K and 1100K (~600°C to ~800°C) by modifying the initial loading ratio of C and CO₂ into the system. The process involves a fluidized bed reactor in which process solids reside where the heat is coupled into or out of the power cycle working fluid through the use of bidirectional heat pipes, and with the gas reactants/products blown through packed beds of the respective zeolite material (copper doped zeolite 5A for CO [3-4], and simple ZSM-5 for CO₂ [5-6]). In this mode, when excess heat is present, the process absorbs some of the heat and stores it as chemical energy in the storage tanks, and when insufficient heat is supplied by the solar field, the process reinjects heat directly into the power cycle.

Boudouard reactors at 5kWh and 10kWh scales have been designed and constructed. Some tests on the reactor have been conducted to examine its performance, including longevity, specific energy, charge and discharge temperatures and exergetic efficiency. Meanwhile, the simulation model has been developed based on the structure of the fluidized bed Boudouard reactor and optimized by matching the experimental data for the prediction of similar applications.

Reference:

[1] Boudouard, O. Influence De La Vapeur D’eau Sur La Réduction De L’anhydride Carbonique Par Le Charbon C. R. Hebd. Acad. Sci. 1905, 141, 252– 253.

[2] Hunt, J.; Ferrari, A.; Lita, A.; Crosswhite, M.; Ashley, B.; Stiegman, A.E. Microwave-Specific Enhancement of the Carbon–Carbon Dioxide (Boudouard) Reaction J. Phys. Chem. C 2013, 117, 26871–26880.

[3] Dulaurent, O.; Courtois, X.; Perrichon, V.; Bianchi, D. “Heats of Adsorption of CO on a Cu/Al2O3 Catalyst Using FTIR Spectroscopy at High Temperatures and under Adsorption Equilibrium Conditions” J. Phys. Chem. B, 2000, 104, 6001–6011.

[4] Saha, D.; Deng, S. Adsorption Equilibria and Kinetics of Carbon Monoxide on Zeolite 5A, 13X, MOF-5, and MOF-177 J. Chem. Eng. Data 2009, 54, 2245–2250.

[5] Wang, Q.; Luo, J.; Zhong, Z.; Borgna, A.CO2 capture by solid adsorbents and their applications: current status and new trends Energy Environ. Sci. 2011, 4, 42-55.

[6] Choi, S; Drese, JH; Jones, CW Adsorbent Materials for Carbon Dioxide Capture from Large Anthropogenic Point Sources ChemSusChem 2009, 2, 796-854.