Chemical Energy Storage System for Solar Electric Generating System (SEGS) Solar Thermal Power Plant

Abstract

The Pacific Northwest Laboratory evaluated the potential feasibility of using chemical energy storage at the Solar Electric Generating System (SEGS) power plants developed by Luz International. Like sensible or latent heat energy storage systems, chemical energy storage can be beneficially applied to solar thermal power plants to dampen the impact of cloud transients, extend the daily operating period, and/or allow a higher fraction of power production to occur during high-valued peak demand periods. Higher energy storage densities make chemical energy storage a potentially attractive option. The results of the evaluation indicated that a system based on the reversible reaction, CaO + H2O = Ca(OH)2, could be technically and economically feasible for this application, but many technical and economic issues must be resolved.

Experimental investigation and model validation of a CaO/Ca(OH)2 fluidized bed reactor for thermochemical energy storage applications

“…Recent research has been focused on the use of thermochemical energy storage (TCS) systems due to their theoretically larger energy storage densities and efficiencies compared to sensible or latent storage [4,8,9]. Basic reaction schemes for TCS systems, including the CaO/Ca(OH) 2 reaction couple, were already proposed in 1976 [10] but they are still at a very early R&D stage from the point of view of their practical development and experimental study at pilot plant scale [10][11][12][13][14][15][16][17]:…”

Composite Material for Thermochemical Energy Storage Using CaO/Ca(OH)2

“…Yet potentially they can yield higher energy storage densities compared to sensible or latent heat storage systems [6][7][8][9] . In particular, we are interested in the use of the calcium oxide hydration/dehydration reaction, proposed by Ervin et al in the late 70's [10][11][12][13] as the basis of some thermochemical energy storage systems [10][11][12][13][14][15][16][17][18][19][20][21] : CaO (s) + H 2 O (g) ↔ Ca(OH) 2 ΔH 298K = -109 kJ/mol (1) This system is based on two steps: during the hydration of CaO in the presence of steam (discharge step), useful thermal heat is released at temperatures over 450ºC.…”

Dehydration/hydration of MgO/H2O chemical thermal storage system

“…MgO(s) þ H 2 O(g) # Mg(OH) 2 (s), DH ¼ À81.02 kJ mol À1 (1) Heat is stored by the dehydration of Mg(OH) 2 (endothermic reaction) and is released by the hydration of MgO (exothermic reaction). Fig.…”

“…Such a system has attracted attention because of its high energy density and capability to store energy for a long time at ambient temperatures. This system can reduce the size of a storage system and store thermal energy seasonally [1]. The MgO/H 2 O system was investigated in this study.…”