Periodic Reporting for period 3 - TPX-Power (Waste Heat Recovery Through Near-Field Thermophotonics)
Período documentado: 2023-07-01 hasta 2025-06-30
Waste heat generated by industry, transport, data processing and other energy intensive processes form enormous energy streams that are typically hard to exploit despite their abundancy. In most cases the low-to-medium exhaust temperatures of the processes make energy re-harvesting challenging with presently available technologies using expensive and bulky mechanical turbines or even the emerging solid state thermophotovoltaic (TPV) or thermoelectric (TE) systems. In TPX-Power we aim to demonstrate a new disruptive approach to thermal energy recovery, ideally allowing a large power density and a competitive energy harvesting efficiency even for low temperature energy streams. The approach harnesses the thermodynamics of electroluminescence (EL), near field (NF) photon transport and photovoltaic (PV) energy production to convert the very recent advances in intracavity thermophotonic (TPX) cooling into a new heat engine technology. The NF TPX heat engines use the superthermal emission from an electrically excited light emitting diode (LED) heated by waste heat, to illuminate a PV cell kept at ambient temperature. This configuration can enable a substantial performance boost compared to existing technologies. To access this potential we build a multidisciplinary consortium providing access to the complementary expertise needed to combine the necessary elements from LEDs, solar cells and NF physics. If successful, TPX-Power can demonstrate and set on motion the development of a cost- and power-efficient heat energy harvesting technology with unprecedented possibilities throughout the sectors where waste heat is produced. At best the technology could nearly double the efficiency of combustion engines and provide a pollution free energy source substantially improving the process efficiency of any waste heat producing process, effectively providing a negative-emission energy source. During the project we designed, fabricated and demonstrated full device prototypes of TPX energy harvesters in small scale, with initial capabilities for near field coupling, thermal insulation and operation at 400-500K temperatures. While the final device assemblies involved all the necessary building blocks, and showed encouraging trends, their full optimization remained inaccessible during the project period, and requires follow-up efforts.
The work carried out during the project primarily focused on setting up a collaborative effort to fabricate and assemble devices that allow studying and demonstrating various near-field coupled thermophotonic systems. This involved intensive process development for sample fabrication as well as setting up the device assemblies where LED and PV components can be placed back to back, with an ability to control the distance between them from far- to near-field. The final results of the project fully demonstrate these capabilities and provide the necessary stepping stones towards the overall project goals. The work has been reported in a number of publications listed on the project website.
The project has advanced beyond the state of the art on several fronts from developing sample architectures suitable for near-field TPX as well as in constructing device assemblies and approaches for their measurements. The work has shown that the fabrication of the devices is challenging, but still feasible in practice. Due to the challenging fabrication, however, the device constructions require additional optimizations before they can reach the efficiency thresholds required for net energy generation.