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Electricity-free heating and cooling strategies for water and energy sustainability


Professor Qiaoqiang Gan

Material Science and Engineering

Physical Science and Engineering Division

King Abdullah University of Science & Technology

Saudi Arabia

Date & Time

Monday, 24 June 2024

3:00 am


Tam Wing Fan Innovation Wing Two G/F, Run Run Shaw Building, HKU


Addressing global challenges necessitates advancements in energy and water sustainability. Direct solar desalination, for instance, holds immense promise for alleviating the worldwide freshwater crisis. This presentation will delve into practical considerations for developing solar heating and radiative cooling applications that promote water and energy sustainability.

Specifically, I will discuss our recent advancements, spanning manufacturing to application development. We will begin by exploring our research efforts to create low-cost solar-driven evaporation architectures using photothermal materials and systems [1-3]. Additionally, we will discuss the potential applications of these architectures for zero-liquid-discharge water treatment using evaporation ponds.

However, if the evaporated moisture cannot be collected, it merely contributes to atmospheric pollution. As the entropy sink, the cold source plays a crucial role in completing the thermodynamic cycle of all heat-producing technologies. The unique challenge lies in obtaining coldness from renewable and sustainable sources.

In the second part of this presentation, we will discuss our recent efforts on radiative cooling in water and energy sustainability [5-9]. Specifically, we will examine the potential of passive cooling technology to recycle atmospheric water. We will also highlight potential pitfalls to avoid in radiative cooling reporting, as summarized in our recent work [10].


1.      Z. Liu, H. Song, D. Ji, C. Li, A. Cheney, Y. Liu, N. Zhang, X. Zeng, B. Chen, J. Gao, Y. Li, X. Liu, D. Aga, S. Jiang, Z. Yu, Q. Gan, “Extremely cost-effective and efficient solar vapor generation under non-concentrated illumination using thermally isolated black paper”, Global Challenges Vol. 1, 1600003, 2017 (Cover article, featured by Science, “Sunlight-powered purifier could clean water for the impoverished”; Salon, “University’s solar-powered still improves ancient water cleaning technology”)

2.      H. Song, Y. Liu, Z. Liu, M. H. Singer, C. Li, A. R. Cheney, D. Ji, L. Zhou, N. Zhang, X. Zeng, Z. Bei, Z. Yu, S. Jiang, Q. Gan, “Cold vapor generation beyond the input solar energy limit”, ‎Adv. Sci. Vol. 5, 1800222, 2018.

3.      K. Yang, T. Pan, S. Dang, Q. Gan, Y. Han, “Three-dimensional open architecture enabling salt-rejection solar evaporators with boosted water production efficiency”, Nature Comm. Vol. 13, 6653, 2022.

4.      U. Kunjaram, H. Song, Y. Liu, B. Booker, T. J Cooke, Q. Gan, “A self-salt-cleaning architecture in cold vapor generation system for hypersaline brines”, EcoMat Vol. 4, e12168, 2022.

5.      L. Zhou, H. Song, J. Liang, M. Singer, M. Zhou, E. Stegenburgs, N. Zhang, C. Xu, T. Ng, Z. Yu†, B. S. Ooi, Q. Gan, “A polydimethylsiloxane coated metal structure for all-day radiative cooling”, Nature Sustainability Vol. 2, 718, 2019.

6.      L. Zhou, H. Song, N. Zhang, M. Singer, H. Zhang, B. Ooi, Z. Yu, Q. Gan, “Hybrid concentrated radiative cooling and solar heating in a single system”, Cell Reports Physical Science Vol. 2, 100338, 2021 (featured by Nature on Feb. 18, 2021: ‘A heat-radiating material goes sideways to keep its cool’).

7.      M. Zhou , H. Song , X. Xu , A. Shahsafi , Z. Xia , Z. Ma , M. Kats , J. Zhu , B. Ooi , Q. Gan, Z. Yu, “Vapor condensation with daytime radiative cooling”, Proceedings of National Academy of Sciences Vol. 118, e2019292118, 2021.

8.      L. Zhou, J. Rada, H. Zhang, H. Song, S. Mirniaharikandi, B. Ooi, Q. Gan, “Sustainable and inexpensive polydimethylsiloxane sponges for daytime radiative cooling”, Adv. Sci. Vol. 8, 2102502, 2021.

9.      R. Galib, Y. Tian, Y. Lei, S. Dang, X. Li, A. Yudhanto, G. Lubineau and Q. Gan, “Atmospheric-moisture-induced polyacrylate hydrogels for hybrid passive cooling”, Nature Comm. Vol. 14, 6707, 2023.

10.    L. Zhou, X. Yin, Q. Gan, “Best practices for radiative cooling”, Nature Sustainability Vol. 6, 1030–1032, 2023.


Dr. Qiaoqiang Gan is a Professor in MSE program (PSE) who joined KAUST in late 2021. He received his PhD degree from Lehigh University in 2010. He is the recipient of Exceptional Young Investigator of University at Buffalo (2016), the Senior Researcher of the Year 2017 of School of Engineering and Applied Science, and SUNY Chancellor's Award for Excellence in Scholarship & Creative Activities 2019. He is the founder of Sunny Clean Water LLC (2017), a high-tech start-up company working on solar water purification technologies. His research publications include over 130 technical papers and 4 patents. He serves as the Editor-in-Chief for IEEE JSTQE, associate editor J. of Photonics for Energy (SPIE) and PhotoniX (Springer), the sub-committee chair of CLEO 2019-2020, the program chair of CLEO 2021 and the General Chair of CLEO 2023.


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