Review maps four technical pathways for atmospheric water harvesting and links refrigeration to SDG 6

A decentralised complement to conventional water supply

A review paper published in Applied Thermal Engineering by an international team from BRAC University (Bangladesh) and Swinburne University of Technology (Australia) examines how atmospheric water harvesting (AWH) can produce freshwater directly from moisture in the air. The authors position AWH as a decentralised, complementary solution that does not depend on surface or groundwater resources, making it particularly relevant for remote, off-grid, and disaster-prone regions where conventional options — desalination, wastewater recycling, and rainwater harvesting — are constrained by infrastructure needs, energy consumption, environmental impacts, rainfall dependence, or geography.

Four technical pathways

The review classifies AWH into four main approaches:

• Condensation-based systems use vapour-compression refrigeration or thermoelectric cooling to drop air temperature below its dew point so that vapour condenses and is collected. They perform well in humid climates but can demand substantial energy input.
• Sorption-based systems employ hygroscopic materials — desiccants or metal-organic frameworks (MOFs) — to capture atmospheric moisture and release it through heating. They can operate at relatively low humidity, though thermal energy is required for regeneration.
• Radiative cooling systems exploit heat loss to the night sky to cool surfaces and promote dew formation without electricity. Yields are generally limited and strongly weather-dependent.
• Hybrid systems combine two or more harvesting mechanisms to improve efficiency and adaptability across climates, at the cost of greater system complexity and expense.

Recent advances and open challenges

The authors point to three trends expanding AWH's potential: innovative sorbent materials, improved cooling technologies, and integration with renewable energy. In particular, advances in MOFs now allow moisture capture at relative humidity levels as low as 10–20 %, and solar-powered configurations open the door to autonomous operation. The review also cites a recent experimental solar-powered thermoelectric water-harvesting system that demonstrated water production under real climatic conditions and met basic microbial safety requirements.

Despite these advances, the authors identify energy consumption, equipment costs, variable water yields, and the need for reliable water-quality control as the principal barriers to widespread deployment. Promising directions they outline include hybrid system development, improved materials, waste-heat utilisation, and the integration of machine learning and smart control systems.

Refrigeration's role in the global water agenda

The IIR's 60th Technical Brief, The Role of Refrigeration in the Global Economy (3rd edition, 2025), highlights refrigeration-based innovations such as AWH as a contribution to UN Sustainable Development Goal 6, which aims to ensure access to clean water and sanitation for all. The review authors note that further technological development and real-world validation will be essential to improve the economic viability of AWH solutions and support their broader deployment.

References

[1] Saha, G., Imran, M. T., Shams, S. M., Khan, M. F. A., Azad, A. K. M. A. M., Imteaz, M. A. (2026). From air to water: science, technology, and future of atmospheric water harvesting (AWH). Applied Thermal Engineering 302, 132073. https://doi.org/10.1016/j.applthermaleng.2026.132073 (open access).

[2] IIR (2025). The Role of Refrigeration in the Global Economy. 3rd edition. 60th Technical Brief on Refrigeration Technologies. International Institute of Refrigeration, Paris. http://dx.doi.org/10.18462/iir.TechBrief.04.2025

[3] United Nations. Goal 6: Clean water and sanitation. https://jointsdgfund.org/sustainable-development-goals/goal-6-clean-water-and-sanitation

Source: IIR sector monitoring.