Periodic Reporting for period 1 - BLAZETEC (BREAKTHROUGHS IN THERMAL BATTERIES THROUGH ZERO-EMISSION HIGH-TEMPERATURE STATIC THERMAL-TO-ELECTRIC CONVERTERS)
Período documentado: 2024-07-01 hasta 2025-12-31
Europe’s transition to a climate neutral energy system requires new ways to store and convert heat into electricity with high efficiency and without greenhouse gas emission. Today, electricity from renewables is increasingly abundant, but storing it cost-effectively and converting high-temperature thermal energy into electricity remain major technological gaps, limiting the application of concentrated solar power, long duration storage systems, and decarbonisation of industry.
The BLAZETEC project addresses these challenges by developing a new class of static, high efficiency thermal-to-electrical converters, capable of operating at ultra-high temperatures (>1200 °C) with no moving parts. The project focuses on three advanced technologies:
• Thermionic generators (TIGs), which convert heat directly into electricity using thermally-assisted electron emission;
• Thermophotovoltaic (TPV) cells, which generate electricity from high temperature IR radiation emitted from a hot source;
• Thermoelectric generators (TEGs), which exploit Seebeck effect from temperature gradients across semiconducting materials.
BLAZETEC pushes these technologies beyond the current state of the art and then hybridises them into combined converters—TIPV (thermionic-photovoltaic) and TITEG (thermionic-thermoelectric) generators—to achieve significantly higher efficiencies than the individual technologies, proposing a solid-state, static and scalable alternative to thermomechanical engines (turbines, Stirling, Rankine, etc.).
The hybridised converters are being integrated into two pilot scale thermal battery concepts:
• a latent heat thermal battery integrating a TIPV converter, operating according to electricity-heat-electricity cycles,
• a sensible heat thermal battery integrating a TITEG converter, operating according to solar-heat-electricity cycles.
These pilots are essential intermediate step demonstrators towards larger-scale, dispatchable renewable energy systems able to supply clean electricity on demand, with potential impacts in industrial heat decarbonisation, concentrated solar power, and markets of high-temperature components and energy storage technology.
The BLAZETEC project addresses these challenges by developing a new class of static, high efficiency thermal-to-electrical converters, capable of operating at ultra-high temperatures (>1200 °C) with no moving parts. The project focuses on three advanced technologies:
• Thermionic generators (TIGs), which convert heat directly into electricity using thermally-assisted electron emission;
• Thermophotovoltaic (TPV) cells, which generate electricity from high temperature IR radiation emitted from a hot source;
• Thermoelectric generators (TEGs), which exploit Seebeck effect from temperature gradients across semiconducting materials.
BLAZETEC pushes these technologies beyond the current state of the art and then hybridises them into combined converters—TIPV (thermionic-photovoltaic) and TITEG (thermionic-thermoelectric) generators—to achieve significantly higher efficiencies than the individual technologies, proposing a solid-state, static and scalable alternative to thermomechanical engines (turbines, Stirling, Rankine, etc.).
The hybridised converters are being integrated into two pilot scale thermal battery concepts:
• a latent heat thermal battery integrating a TIPV converter, operating according to electricity-heat-electricity cycles,
• a sensible heat thermal battery integrating a TITEG converter, operating according to solar-heat-electricity cycles.
These pilots are essential intermediate step demonstrators towards larger-scale, dispatchable renewable energy systems able to supply clean electricity on demand, with potential impacts in industrial heat decarbonisation, concentrated solar power, and markets of high-temperature components and energy storage technology.
During the first 18 months of activity, BLAZETEC carried out an extensive programme of design, simulation and experimental activities aimed to define the operating conditions, to develop active materials and architectures required for the converters and pilot systems.
1. Development of optimized independent conversion technologies. All three stand-alone converters were fully specified:
• For the vacuum-TIG, operating parameters for electrodes such as work function, Richardson constant, inter-electrode distance, and thermal management were established. Detailed modelling identified 2.3–2.6 eV and 1.6–1.7 eV as the optimal cathode and anode work function values to achieve the targets for conversion efficiency and output power density. Experimental activities confirmed the importance of microfabricated dielectric spacers and planarity to control the vacuum gap and improve the converter performance. The first vacuum-TIGs demonstrated operating capability up to 1200 °C without any degradation, and up to 1400 °C with a slow cathode degradation.
• The cascaded TEG architecture was defined, combining high temperature SiGe modules with mid temperature commercial modules. Thermal mechanical analyses and simulations confirmed achievable efficiencies around 11% at 1000 °C, with a clear pathway to 15% using nanostructured materials.
• For the TPV converter, a complete roadmap was developed toward a high performance tandem TPV cell that boosts power density and conversion efficiencies. Early epitaxy and simulations confirmed the potential to exceed 4 W cm⁻² and 40% efficiency at 1200–1600 °C thermal source conditions.
2. Development of hybrid converters: TIPV and TITEG. The project defined the architectures, interfaces and manufacturing routes for both hybrid systems:
• For TITEG, the team designed a combined system in which a high temperature TIG supplies heat directly to a cascaded TEG. The critical thermal interface was analysed, and practical solutions using refractory metals and ceramic pastes were established, alongside spring-assisted assemblies to manage thermal expansion.
• For TIPV, the design integrates a transparent, low-work-function thermionic anode directly on top of a TPV cell. The project developed four TPV design configurations, progressively increasing complexity, and determined compatible coating and dielectric microspacer solutions that preserve transparency to IR radiation as well as thermal and electrical insulation, respectively.
3. Pilot system conceptual design
Two pilot thermal battery demonstrators were fully defined:
• Pilot 1 (latent heat) uses FeSi-based phase change materials operating at 1200–1400 °C within a 12 kW electric furnace. Key performance indicators, thermal layout, mechanical interfaces and testing schedule were produced.
• Pilot 2 (sensible heat) will operate at the PROTEAS solar tower in Cyprus with a ~30 kg SiC storage unit, a secondary concentrator, and the TITEG converter. High-fidelity raytracing simulations validated the ability to deliver the required 45 W cm⁻² solar flux on the SiC absorber.
All deliverables planned for this period were completed on time and approved.
1. Development of optimized independent conversion technologies. All three stand-alone converters were fully specified:
• For the vacuum-TIG, operating parameters for electrodes such as work function, Richardson constant, inter-electrode distance, and thermal management were established. Detailed modelling identified 2.3–2.6 eV and 1.6–1.7 eV as the optimal cathode and anode work function values to achieve the targets for conversion efficiency and output power density. Experimental activities confirmed the importance of microfabricated dielectric spacers and planarity to control the vacuum gap and improve the converter performance. The first vacuum-TIGs demonstrated operating capability up to 1200 °C without any degradation, and up to 1400 °C with a slow cathode degradation.
• The cascaded TEG architecture was defined, combining high temperature SiGe modules with mid temperature commercial modules. Thermal mechanical analyses and simulations confirmed achievable efficiencies around 11% at 1000 °C, with a clear pathway to 15% using nanostructured materials.
• For the TPV converter, a complete roadmap was developed toward a high performance tandem TPV cell that boosts power density and conversion efficiencies. Early epitaxy and simulations confirmed the potential to exceed 4 W cm⁻² and 40% efficiency at 1200–1600 °C thermal source conditions.
2. Development of hybrid converters: TIPV and TITEG. The project defined the architectures, interfaces and manufacturing routes for both hybrid systems:
• For TITEG, the team designed a combined system in which a high temperature TIG supplies heat directly to a cascaded TEG. The critical thermal interface was analysed, and practical solutions using refractory metals and ceramic pastes were established, alongside spring-assisted assemblies to manage thermal expansion.
• For TIPV, the design integrates a transparent, low-work-function thermionic anode directly on top of a TPV cell. The project developed four TPV design configurations, progressively increasing complexity, and determined compatible coating and dielectric microspacer solutions that preserve transparency to IR radiation as well as thermal and electrical insulation, respectively.
3. Pilot system conceptual design
Two pilot thermal battery demonstrators were fully defined:
• Pilot 1 (latent heat) uses FeSi-based phase change materials operating at 1200–1400 °C within a 12 kW electric furnace. Key performance indicators, thermal layout, mechanical interfaces and testing schedule were produced.
• Pilot 2 (sensible heat) will operate at the PROTEAS solar tower in Cyprus with a ~30 kg SiC storage unit, a secondary concentrator, and the TITEG converter. High-fidelity raytracing simulations validated the ability to deliver the required 45 W cm⁻² solar flux on the SiC absorber.
All deliverables planned for this period were completed on time and approved.
The project has already delivered several advances with significant potential impact:
• New validated operating windows for TIG, TPV and TEG devices at temperatures up to 1600 °C.
• The first vacuum-TIGs demonstrated operativity up to 1400 °C.
• First integrated design pathway for TIPV and TITEG, combining multiple conversion mechanisms to surpass the efficiency limits and output power of individual technologies.
• Advanced material-science strategies, including ultrathin low thin low work-function coatings, dielectric microspacers, metamorphic low bandgap junctions and nanostructured thermoelectric alloys.
• Pilot scale designs showing feasible pathways to achieve high-temperature, dispatchable power generation.
The expected longer-term impacts include:
• enabling high efficiency thermal-to-electric conversion for renewable heat and industrial waste heat;
• making concentrated solar power competitive with photovoltaic with storage at small capacities;
• contributing to European industrial leadership in high-temperature materials and components, vacuum devices, and power conversion static technologies;
• preparing the ground for future demonstration activities and potential commercial deployment in process heat, solar power, and grid-balancing markets.
Further work will focus on manufacturing the converters, integrating them into vacuum enclosures, validating experimentally the performance, and implementing the two pilot systems.
• New validated operating windows for TIG, TPV and TEG devices at temperatures up to 1600 °C.
• The first vacuum-TIGs demonstrated operativity up to 1400 °C.
• First integrated design pathway for TIPV and TITEG, combining multiple conversion mechanisms to surpass the efficiency limits and output power of individual technologies.
• Advanced material-science strategies, including ultrathin low thin low work-function coatings, dielectric microspacers, metamorphic low bandgap junctions and nanostructured thermoelectric alloys.
• Pilot scale designs showing feasible pathways to achieve high-temperature, dispatchable power generation.
The expected longer-term impacts include:
• enabling high efficiency thermal-to-electric conversion for renewable heat and industrial waste heat;
• making concentrated solar power competitive with photovoltaic with storage at small capacities;
• contributing to European industrial leadership in high-temperature materials and components, vacuum devices, and power conversion static technologies;
• preparing the ground for future demonstration activities and potential commercial deployment in process heat, solar power, and grid-balancing markets.
Further work will focus on manufacturing the converters, integrating them into vacuum enclosures, validating experimentally the performance, and implementing the two pilot systems.