Hybrid Photothermal Pyroelectric and Thermogalvanic Generator for Multisituation Low Grade Heat Harvesting

Abstract

operation. Seemingly, the intermittency issue can be circumvented, by alternatively intercepting and capturing of solar thermal energy fluxes. Moreover, low grade solar thermal harvesting has attracted significant interest because of its versatility in numerous applications such as steam generation, [1][2][3][4][5] photo/electrocatalysis, [6][7][8][9][10][11][12] energy harvesters, [13][14][15][16][17] and actuators. [18][19][20][21][22][23][24] Also, harvesting of ubiquitous low grade waste heat is presently perceived as a promising energy source toward decarbonized and sustainable ecology.Thermoelectric generator and pyroelectric generator, which can convert thermal energy directly into electricity, are the two particularly attractive ways for solar heat utilization, ascribing to their merits, that is, simple structure, no moving parts and devoid of mechanical deformation. [25][26][27][28][29][30][31] Thermoelectric generator harvests energy via the Seebeck effect triggered by static temperature differences, while the pyroelectric generator delivers through the change of spontaneous polarization in response to dynamic temperature fluctuations. However, most conventional thermoelectric generators are based on high-cost and complicated fabrication of solid-state semiconducting materials constricted by physical limitations and rarely, if ever, attempts have been made to hybrid with other types of thermal energy generator. As an alternative to thermoelectric modules, thermocell (also known as thermogalvanic cell) that utilizes the temperature-dependent entropy changes during electron transfer between redox couples and electrodes is a promising method to convert thermal energy to electricity, with the virtues of relatively high Seebeck coefficient, inexpensive and simple fabrication process. [32][33][34][35] Besides, solar thermal effect induced by an unstructured outdoor environment is inevitably accompanied by thermal fluctuations caused by ever-changing weather condition. Such thermal variance has dramatically impeded some thermal devices to reach their maximum attainable performance. Hence, a judicious design and integration of thermogalvanic and pyroelectric generator can critically underpin effective utilization of solar thermal resource by harvesting energy from static temperature difference derived from a constant solar exposure as well as dynamic temperature fluctuations arising from sporadic ambience.Harvesting of prevalent low grade solar heat from otherwise wasted energy has received tremendous attention. However, extensive and continuous conversion remains challenging due to distributed nature of heat, limited temperature difference with the surroundings, ambient solar heat fluctuation, and night time period of darkness. Herein, a hybrid thermogalvanic and pyroelectric generator for multisituation structured/unstructured, static/dynamic, and day/night waste heat harnessing for continuous operation is reported. Powered by versatile thermal energy harvesting strategies, the hybrid photothermal generator i...

Shape Conformal and Thermal Insulative Organic Solar Absorber Sponge for Photothermal Water Evaporation and Thermoelectric Power Generation

“…This low-grade solar heat is perceived as a promising energy source for waste energy-to-electricity conversion. [35] We used a TE module to harvest the low-grade heat via the Seebeck effect triggered by static temperature differences between the solar absorber and bulk water (Figure 5a,b). [42][43][44] The PCC sponges are readily shaped to conformally cover the upper side of TE module with a wall contacting with bulk water for efficient water transportation (Figure 5b).…”

“…Hence, a TE module which is triggered by static temperature differences via the Seebeck effect was used to harvest this low-grade solar heat for waste energy-to-electricity conversion. [35] Meanwhile, the TE module serves as a thermal insulator under PCC sponge to promote the solar evaporation. This approach provides a new opportunity for generating fresh water and electricity ondemand/on-site which is especially attractive for off-grid areas.…”

Multifunctional Skin‐Inspired Flexible Sensor Systems for Wearable Electronics

“…To boost the output power of thermoelectric generators, although, as an alternatively promising strategy, thermocells have been applied to harvest waste heat based on electrons transfer between redox couples and electrodes due to the nature of relatively high Seebeck coefficient, such steady temperature variations are scarce in natural surroundings . On the contrary, pyroelectric generators (PyNGs) are subjected to time dependent temperature fluctuation so as to trigger the energy conversion processes . For example, the temperature of body exhaled gas is similar to human body, which is generally higher than the environmental temperature, especially in winter.…”

Harnessing Solar‐Driven Photothermal Effect toward the Water–Energy Nexus

“…[160,161] It is worth noting that the maximum output power was achieved to 0.05 mW (external resistance is about 2 Ω) when the thermoelectric module was used as heat insulator of water evaporator. However, this case requires a high energy input (up to 30 kW m −2 ).…”