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.
