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 abundance. 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 the emerging solid state thermophotovoltaic (TPV) or thermoelectric (TE) systems. In TPX-POWER we aim to demonstrate a new approach to thermal energy recovery, fundamentally 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. If successful, TPX-POWER demonstrates and sets 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. In most optimal scenarios the technology could double the efficiency of combustion engines and provide a pollution free energy source substantially improving the process efficiency of any waste heat producing process, providing an essentially negative-emission energy source.