Techno-economic analysis of atmospheric water generation by hybrid nanofluids to mitigate global water scarcity

Abstract

Globally, multiple efforts are made to develop active atmospheric water generation (AWG) or atmospheric water extraction (AWE) systems, particularly using direct-air cooling technology to produce water from ambient air. However, this legacy technique is highly energy-intensive, it can only be operated when the local dew point is above the freezing point of water, allows bacteria to grow within the system, and does not scale to create enough water to offer solutions for most industries, services, or agriculture. Liquid desiccant-based AWG methods show promising performance advantages and offer a versatile approach to help address the thermodynamic, health risks, and geographic constraints currently encountered by conventional active AWG systems. In this study, we performed a techno-economic analysis of a liquid desiccant-based AWG system with a continuous operating style. An energy balance was performed on a single design point of AWG system configuration while using LiCl liquid desiccant loaded with multi-walled carbon nanotubes (MWCNTs). We showed that the MWCNTs can be doped in LiCl for effective heat transfer during water desorption, resulting in a lowering of the sensible heat load by ≈ 49% on the AWG system. We demonstrated that the specific energy consumption (SEC) can currently be obtained as low as 0.67 kWh/gal while changing the inlet desiccant stream concentration of MWCNTs-doped LiCl at given conditions. While the production cost of water (COW) showed a significant dependency over the region, the economic analysis revealed that the cost of water can be produced at a minimum selling price of $0.085 per gallon based on the 2021 annual average wholesale electricity cost of $0.125 per kWh in the U.S., thereby, providing a strong foundation for future research to meet the desirable and competitive water costs by 2026 but before 2031.