In the quest for sustainable energy solutions, researchers Tarique Anwar and Giulia Tagliabue from the Swiss Federal Institute of Technology in Lausanne (EPFL) have introduced a novel approach to harnessing energy from heat and light. Their work, published in the journal Nature Communications, focuses on evaporation-driven hydrovoltaic (EDHV) devices, which offer a promising avenue for converting ambient heat and solar energy into electricity.
Traditional EDHV devices primarily rely on ion streaming at the solid-liquid interface to generate electricity. However, Anwar and Tagliabue’s research presents a unified framework that goes beyond this mechanism. Their approach combines thermodiffusion and photovoltaic effects to effectively transform waste heat and solar energy into electrical power. The researchers utilized a unique device structure featuring a top-evaporating surface paired with a bottom silicon-dielectric (core-shell) nanopillar array separated by a liquid layer. This design demonstrated significant enhancements in power output under external heating and solar illumination.
The study revealed that, in addition to the movement of a polar solvent like water or ethanol and ions in a narrow, partially wetted top electrode region, thermally and light-assisted ion migration from the bottom to the top electrode plays a crucial role in electricity generation. To quantify this contribution, the researchers developed an equivalent electrical circuit model, introducing a capacitive element called transfer capacitance.
The researchers achieved impressive results with their EDHV devices, including an open-circuit voltage of 1V and an output power density of 0.25W/m2 at a concentration of 0.1M. They also highlighted the critical influence of material selection on device performance. For instance, transitioning from a TiO2 to an Al2O3 dielectric shell resulted in voltage and power enhancements of up to 1.9 times and 3.6 times, respectively, at 25°C. Additionally, high silicon doping yielded a 28% increase in open-circuit voltage and a 1.6-fold improvement in power output compared to low-doped samples.
The findings of this research provide valuable insights into advancing EDHV devices and suggest broader operational strategies that consider environmental conditions, water salinity, and material engineering to optimize the utilization of waste heat and sunlight. For the energy industry, this technology could offer a sustainable and efficient way to harness energy from otherwise wasted heat and solar resources, potentially contributing to the development of more efficient power generation systems.
Source: Nature Communications, “A Unified Framework for Harnessing Heat and Light with Hydrovoltaic Devices” by Tarique Anwar and Giulia Tagliabue.
This article is based on research available at arXiv.