Energy storage/withdrawal system for a facility

Abstract

The invention relates to a system ( 100 ) for storing/withdrawing thermal energy. The main characteristic of a system according to the invention is that it comprises: a monolithic cementitious material ( 1 ) comprising a mass fraction of ettringite of greater than 20%, said material being surrounded by a thermal insulation material ( 12 ) and a water insulation material ( 11 ), a source ( 2 ) of a heat transfer fluid, a device ( 3 ) for wetting said fluid in order to carry out a withdrawal phase of the system ( 100 ), a device ( 4 ) for heating said fluid in order to carry out a storage phase of said system ( 100 ), an outlet ( 6 ) of the heat transfer fluid from said material ( 1 ).

1 . System for storing/withdrawing thermal energy, comprising
 a monolithic cementitious material comprising a mass fraction of ettringite of greater than 20%, said material being surrounded by a thermal insulation material and a water insulation material,   a source of a heat transfer fluid,   a device for wetting said fluid in order to carry out a withdrawal phase of the system,   a device for heating said fluid in order to carry out a storage phase of said system,   an outlet of the heat transfer fluid from said material,   wherein said system comprises at least one heat transfer fluid circulation circuit that passes through the heating device and through the wetting device, said circuit being supplied by the source of said fluid and leading to the cementitious material.   
     
     
         2 . System according to  claim 1 , wherein the heat transfer fluid is formed by an inert gas. 
     
     
         3 . System according to  claim 1 , wherein the source of the heat transfer fluid is placed upstream of the wetting device, which is itself placed upstream of the heating device, and in that said heating device is placed upstream of the cementitious material. 
     
     
         4 . System according to  claim 1 , wherein the wetting device and the heating device each operate to order, and can be activated independently of one another depending on the use of said system, either in storage phase, or in withdrawal phase. 
     
     
         5 . System according to  claim 1 , wherein the mass fraction of ettringite in the cementitious material is between 20% and 90%. 
     
     
         6 . System according to  claim 1 , wherein the cementitious material has a porosity of between 10% and 90%. 
     
     
         7 . System according to  claim 1 , wherein the cementitious material ( 1 ) has a permeability of between 10 −17  m 2  and 10 −11  m 2 . 
     
     
         8 . System according to  claim 1 , wherein the cementitious material ( 1 ) has a compressive mechanical strength of between 0.1 MPa and 70 MPa. 
     
     
         9 . System according to  claim 1 , wherein the water insulation material is formed by an impermeable wall intended to prevent water vapour from coming into contact with the cementitious material. 
     
     
         10 . System according to  claim 1 , wherein the thermal insulation material is formed by at least one material to be chosen from glass wool and polystyrene and in that said at least one impermeable material is placed around the water insulation material. 
     
     
         11 . System according to  claim 1 , wherein the wetting device comprises at least one humidifier suitable for charging said fluid with water. 
     
     
         12 . Process for storing/withdrawing thermal energy using a storage/withdrawal system in accordance with  claim 1 , wherein, in the heat storage phase, it comprises the following steps:
 a step of heating the heat transfer fluid by means of the heating device in order to obtain a hot gas, the temperature of which is above 30° C.,   a step of directly passing said hot gas through the cementitious material comprising ettringite, giving rise to an endothermic dehydration of said material and constituting a heat storage phase.   
     
     
         13 . Process according to  claim 12 , wherein the heat storage phase extends over a period of several days, said period being dictated by the amount of cementitious material and the flow rate of fluid used in said process. 
     
     
         14 . Process according to  claim 12 , wherein, in the heat withdrawal phase, it comprises the following steps:
 a step of wetting the heat transfer fluid by means of the wetting device in order to obtain a wetted gas,   a step of directly passing said wetted gas through the cementitious material comprising ettringite and which adsorbs water vapour then is hydrated,   a step of exothermic reaction which generates heat transported by the heat transfer fluid, converting the initially cold and wet gas into a hot and dry gas.   
     
     
         15 . Process according to  claim 12 , wherein said process comprises a step of removing the carbon dioxide in the heat transfer fluid before it passes through the cementitious material comprising ettringite in order to prevent a carbonation reaction of said material. 
     
     
         16 . Material comprising ettringite for creating a system in accordance with  claim 1 . 
     
     
         17 . Material according to  claim 16 , wherein said material comprises an ettringitic binder, the porosity and the permeability of which are increased by chemical foaming and/or by mechanical foaming.