Present Status and Challenges with Water Harvesting through Dehumidification in Indoor Farming Applications

Humidity control is a critical challenge for closed indoor agricultural systems, regardless of the geographic location, climate, structure type, or crop. While numerous dehumidification techniques are employed, most are energy-intensive and have sustainability challenges. This review comprehensively evaluates existing dehumidification technologies for closed indoor farming systems such as greenhouses and vertical farms. It details the working principles of various dehumidifiers and assesses their energy efficiency and environmental benefits, helping growers prioritize energy-specific strategies. Additionally, models predicting the dehumidification load based on moisture and energy balances are elaborated, identifying key greenhouse parameters critical for humidity control. The review highlights emerging dehumidification technologies, particularly those driven by renewable energy, such as desiccant-based dehumidification and metal-organic frameworks (MOFs). These technologies promise enhanced sustainability when paired with renewable energy sources such as solar and geothermal. Mechanical dehumidification is recommended for precise and instantaneous microclimate control, but it is energy- and carbon-intensive. The analysis concludes that renewable-energy-based novel dehumidification systems offer the most promising avenue for sustainable indoor farming, though further research is necessary to enhance their efficiency and practicality. This review serves as a valuable resource for growers and practitioners, guiding the selection of appropriate dehumidification technologies based on specific operational priorities. It also underscores the need for continued research to optimize energy use and reduce the carbon footprint associated with humidity management in indoor agriculture.