Silt Soil–Driven Hydrovoltaic Generators for Eco-Friendly and Scalable Energy Harvesting

초록

Soil is a naturally abundant and globally available resource, with unique physicochemical properties that make it an attractive candidate for hydrovoltaic (HV) energy harvesting. Among the four major soil types—sandy, silt, clay, and loamy—silt soil is particularly rich in oxygen-containing functional groups and microbial activity, exhibiting strong hydrophilicity and rapid capillary action. These features promote efficient formation of electrical double layers (EDLs) when water flows through the soil, enabling electricity generation via HV mechanisms. In this study, we demonstrate for the first time that unmodified silt soil can act as an effective active medium for HV generators. A single soil-based device generated an open-circuit voltage of approximately 258–280 mV and a short-circuit current of approximately 15 µA under ambient conditions using symmetric aluminum electrodes, while it delivers approximately 248 mV/approximately 10–12 µA inert carbon electrodes. The system exhibited long-term operational stability over 8 months, with excellent photothermal and evaporation ability, and enhanced output under light exposure. Under moisture content over 60% and low acidic nature in soil, the device performs a high power output highly demanding in the tropical or subtropical regions. Multiple devices connected in series and parallel successfully powered LEDs, calculators, and even charged a mobile phone via capacitive storage. This work establishes soil as a low-cost, eco-friendly, and scalable energy source for powering low-power electronics. Its universal accessibility and chemical-free nature make it especially promising for off-grid, low-resource settings and emergency scenarios—enabling sustainable electricity generation virtually anywhere in the world.

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