Periodic Reporting for period 2 - TPX-Power (Waste Heat Recovery Through Near-Field Thermophotonics)
Okres sprawozdawczy: 2022-01-01 do 2023-06-30
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.
The work carried out during the first reporting period has primarily focused on setting up the collaboration and on 1) establishing a better picture of the limiting performance of the devices using parametric thermodynamic models, 2) developing our capabilities to analyze the devices e.g. using analytic models and semiempirical measurement fitting, 3) testing and optimizing epitaxial lift-off (ELO) techniques and materials forming a baseline for further development, 4) implementing new contacting schemes required by vacuum gaps and near-field enabled structures and 5) exploring various approaches to support and characterize the vacuum gap structures, in anticipation of the most likely needs towards the later parts of the project.
The project has this far advanced beyond the state of the art through improving our understanding of the performance and possibilities offered by thermophotonics. It has also paved way to demonstrating new device structures using vacuum nanogaps by developing new contacting and processing schemes for the devices, expected to lead to fully fledged device prototypes that can efficiently convert low-grade thermal energy into electricity.