Sustained power generation from concentration gradients in a solid matrix†

Abstract

Concentration gradients possess significant energy. However, the inherent fluidity of liquids typically results in rapid energy dissipation, while using membranes to separate solutions with different concentrations introduces fundamental challenges, including excessive material consumption and packaging difficulties. Coupling concentration gradients with solid substrates could effectively address these issues. In this paper, we demonstrate the feasibility of sustaining energy supply through concentration gradients in a solid matrix, while investigating the working principle and output characteristics of the Solid Concentration Gradient Power Generator (SCGPG). Subsequently, the sustained energy supply capability of SCGPGs was demonstrated by powering a series of small electronic devices. To compensate for the finite energy supply caused by spontaneous dissipation of concentration gradients, we proposed two approaches. The first involved a waste heat utilization strategy that maintained concentration gradients through temperature differences, thereby extending the SCGPG's operational duration. The second approach focused on materials and manufacturing methods, where combining water and soil to form water–soil-SCGPGs significantly lowered production costs and expanded the adaptability of SCGPGs. This study breaks the constraints of liquid mobility and membrane dependence in concentration gradient-based power systems, providing a promising approach for economically efficient and sustained concentration gradient energy harvesting.