A Thin Film-bAsed Capacitive Thermoelectric Device with a High Conversion Rate for Harvesting Low-Grade Waste Heat

Recovered energy from waste heat has enormous opportunities to be utilised. Waste heat is classified into high, medium, and low grades based on the temperature range. 50% of the total waste heat falls in the low-grade heat, which compared to the medium-grade heat or the high-grade heat, is challenging to recover. The heat emitted from electronic devices is considered low-grade waste heat.
In a capacitive thermoelectric device, the value of the permittivity of the used dielectric material changes with temperature. This will vary the capacitance value, and as a result, the electrical energy stored in the capacitor. When made using a ferroelectric thin film, due to the small heat mass of the capacitive thermoelectric converter, it is possible to achieve a rapid heating-cooling cycle and therefore to recover substantial wasted heat per unit of time.
In this paper, the experimental results achieved using BSZT thin films with various stoichiometry were used to estimate the power output of a thin film capacitive thermoelectric converter. An Intel E5-2630 microprocessor with a dynamic workload was considered as the source of modulated heat flux.
It is also worth noting the double benefit of the proposed thermoelectric device: in addition to the harvested energy, it will contribute substantially to the cooling of the electronic devices, hence, reducing the demand for external energy required for their active cooling.