Periodic Reporting for period 1 - OXITES (Experimental and computational screening of Oxides for Thermochemical Energy Storage (OxiTES))
Periodo di rendicontazione: 2022-03-01 al 2024-02-29
Around 60% of the energy consumption is currently wasted as heat. The use of chemical reactions to store thermal energy is an attractive goal for domestic and industrial applications as heat also comprises around 50% of end energy usage. Utilizing this invisible potential is therefore paramout for the energy sustainable society, crucial for energy transition and is in line with UN sustainable development goals 7 and 11.
Thermochemical Energy Storage (TCES) based on solid-gas chemical reactions is a promising approach to efficiently store heat that may pave the way towards compact and inexpensice devices with high energy storage density (up to 1 GJ/m3) and with absence of thermal losses, thus making possible advanced usage in numerous industrial processes, for seasonal storage, etc. One of the bottlenecks for this technology is lack of appropriate chemical reactions and materials studied for TCES.
Substantial fraction of the waste heat posesses temperature potential in the medium temperature reason (200-600°C). This industrially relevant temperature interval is very sparsely covered by materials for TCES. Indeed, only decomposition/synthesis Mg(OH)2 (T ~ 350°C), Ca(OH)2 (T ~ 500°C) and MgCO3 (T ~ 400°C) were studied for TCES at medium temperatures. Therefore, the technology lacks flexibility for real use case scenarios.
The project was aimed at extending the material portfolio by sytstematic computationally-aided screening of oxides for TCES. The project contributes to the developing one of the most advanced technologies for thermal energy storage at these temperatures that utilizes the chemical reactions.
The main project objective was using structural databases for screening of potentially promising oxides that can absorb H2O or CO2 at medium temperatures. The particular objectives included:
1. Strucutre selection from the databases based on the developed methodology and using relevant criteria for TCES materials.
2. Theoretical characterization of the oxides, characterization of their electronic strucutre and identifying pontentially promising candidates.
3. Experimental study of the selected materials to verify the reaction reversibility and define relevant parameters (e.g. storage density, reaction temperatures and pressures, etc.)
4. Testing one material in a lab-scale reactor, carrying out several reaction cycles.
Thermochemical Energy Storage (TCES) based on solid-gas chemical reactions is a promising approach to efficiently store heat that may pave the way towards compact and inexpensice devices with high energy storage density (up to 1 GJ/m3) and with absence of thermal losses, thus making possible advanced usage in numerous industrial processes, for seasonal storage, etc. One of the bottlenecks for this technology is lack of appropriate chemical reactions and materials studied for TCES.
Substantial fraction of the waste heat posesses temperature potential in the medium temperature reason (200-600°C). This industrially relevant temperature interval is very sparsely covered by materials for TCES. Indeed, only decomposition/synthesis Mg(OH)2 (T ~ 350°C), Ca(OH)2 (T ~ 500°C) and MgCO3 (T ~ 400°C) were studied for TCES at medium temperatures. Therefore, the technology lacks flexibility for real use case scenarios.
The project was aimed at extending the material portfolio by sytstematic computationally-aided screening of oxides for TCES. The project contributes to the developing one of the most advanced technologies for thermal energy storage at these temperatures that utilizes the chemical reactions.
The main project objective was using structural databases for screening of potentially promising oxides that can absorb H2O or CO2 at medium temperatures. The particular objectives included:
1. Strucutre selection from the databases based on the developed methodology and using relevant criteria for TCES materials.
2. Theoretical characterization of the oxides, characterization of their electronic strucutre and identifying pontentially promising candidates.
3. Experimental study of the selected materials to verify the reaction reversibility and define relevant parameters (e.g. storage density, reaction temperatures and pressures, etc.)
4. Testing one material in a lab-scale reactor, carrying out several reaction cycles.
Work performed during the project:
- A screening methodology was developed to screen databases and make a preliminary analysis of the screening output.
- DFT calculations with characterization of chemical bonding were carried out for the oxide-hydroxide pairs, carbonate-oxide pairs as well as for 340 oxide structures without complementary pairs.
- A symbolic regression reactivity descriptors for hydration and carbonation of oxides were found after thorough verification on the 340-set, and the set of the most promising oxides for TCES at medium temperatures was presented.
- For seven most promising materials hydration/dehydration behaviour was comprehensively studied by thermogravimetric analysis (TGA) under conditions relevant for industrial TCES cycles (T = 200-600°C, P = 0-500 mbar).
- The structural binding of water molecules and reaction reversitiliby were verified by X-ray diffraction analysis (XRD) and TGA techniques.
- The most promisng material was tested in a lab-scale reactor for a long-term cycling experiment.
The brief summary of the main results of the project:
- The reactivity descriptors for hydration and carbonation of oxides based on electronic and structural features were found and verified against the set of parameters from real oxide structures.
- A library of basic oxides potentially reacting at medium temperatures is collected.
- Layered double hydroxide mineral meixnerite was identified as a promising TCES material. Its reactivity at medium temperatures and chemical reversibility was verified for at least 15 cycles.
- A screening methodology was developed to screen databases and make a preliminary analysis of the screening output.
- DFT calculations with characterization of chemical bonding were carried out for the oxide-hydroxide pairs, carbonate-oxide pairs as well as for 340 oxide structures without complementary pairs.
- A symbolic regression reactivity descriptors for hydration and carbonation of oxides were found after thorough verification on the 340-set, and the set of the most promising oxides for TCES at medium temperatures was presented.
- For seven most promising materials hydration/dehydration behaviour was comprehensively studied by thermogravimetric analysis (TGA) under conditions relevant for industrial TCES cycles (T = 200-600°C, P = 0-500 mbar).
- The structural binding of water molecules and reaction reversitiliby were verified by X-ray diffraction analysis (XRD) and TGA techniques.
- The most promisng material was tested in a lab-scale reactor for a long-term cycling experiment.
The brief summary of the main results of the project:
- The reactivity descriptors for hydration and carbonation of oxides based on electronic and structural features were found and verified against the set of parameters from real oxide structures.
- A library of basic oxides potentially reacting at medium temperatures is collected.
- Layered double hydroxide mineral meixnerite was identified as a promising TCES material. Its reactivity at medium temperatures and chemical reversibility was verified for at least 15 cycles.
The project identified a new material that was never studied for TCES before and provided a list of potentially promising candidates along with the guidelines for a further search.
The original methodology developed in the framework of the project may be further used for screening of thermochemical materials among other classes such as salt hydrates or ammoniates.
The results of the project may be interesting for scientific researchers and engineers working on systems for thermochemical energy storage.
The original methodology developed in the framework of the project may be further used for screening of thermochemical materials among other classes such as salt hydrates or ammoniates.
The results of the project may be interesting for scientific researchers and engineers working on systems for thermochemical energy storage.