Day-Night energy harvesting: Photovoltaics-driven moisture evaporation and absorption for simultaneous 24-hour power and dehumidification
Lei Che, Niansi Li, Wei Wei, Jing Li, Jie Ji, Xudong Zhao, Bendong Yu, Qiliang Wang
Abstract
<p>Building sector is a significant contributor to global carbon emission, primarily driven by electricity consumption and air-conditioning demands. A sustainable pathway toward building decarbonization involves harnessing solar energy to simultaneously generate electricity and address indoor humidity control. In this work, we present an innovative hybrid system that integrates photovoltaic cells, thermoelectric generators, and metal-organic frameworks to enable all-day power generation and efficient air dehumidification. This system leverages the synergy between moisture-induced adsorption/desorption heat from MOFs and the harvesting of solar heat and radiative cooling from PV cells. Notably, the synergistic effects significantly enhanced the PV efficiency of the photovoltaic cell by 23% due to the intensified heat exchange during moisture desorption, and increased the average thermoelectric efficiency by 353%. Additionally, it effectively reduced the air relative humidity from an average of 79.12% to 63.34% within 4 hours. We further demonstrate the application of this hybrid system on building roofs, achieving maximum power densities of 88 W·m<sup>-2</sup> during the day and 2.12 W·m<sup>-2</sup> at night in Nanjing, respectively. Across various cities in China, the system shows the annual power generated ranges from 1.08×10<sup>4</sup> to 1.69×10<sup>4</sup> kW, along with air-conditioning energy savings between 29 and 498 kW. This novel approach provides a low-energy and sustainable solution for continuous power generation and air dehumidification, supporting the decarbonization of buildings.<br/> </p>