Chung-Ang University Achieves Dual-Purpose Breakthrough: Turning Water into Electricity While Detecting Fires

Researchers developed a novel hydrovoltaic device that generates electricity from water and functions as a fast-response fire detector

SEOUL, South Korea, Jan. 23, 2025 /PRNewswire/ -- Various clean energy technologies have been developed to meet the rapidly intensifying energy demand and dwindling fossil fuel reserves. However, many of these technologies are hindered by low efficiency and high costs. Hydrovoltaic (HV) mechanisms, in which electricity is generated by the direct interaction of nanostructured materials and water molecules, have recently emerged as promising, cost-efficient alternatives. HV systems show particular promise for powering electrical sensors, including fire sensors.

Traditional fire sensors rely on batteries to operate during power outages, which can explode during fires. In contrast, HV systems draw energy from water, with the device partially immersed in it. Additionally, traditional fire sensors often trigger false alarms due to cooking smoke, steam, or dust, and require high maintenance. HV systems overcome these limitations by responding only to evaporation-driven changes to water flow, such as those caused by fire. However, their use in fire-sensing applications has not been explored until now.

In a recent study, a research team led by Associate Professor Byungil Hwang from the School of Integrative Engineering at Chung-Ang University developed an innovative HV device that doubles as a fire sensor. "Our hydrovoltaic system can produce up to a few tens of microwatts, making it perfect for small-scale applications like fire detectors and health monitoring systems. This system is self-reliant, requires only a few milliliters of water, and has a fast response time," explains Prof. Hwang. Their study was made available online on January 04, 2025, and published in the Chemical Engineering Journal on February 01, 2025.

HV systems consist of hydrophilic substrates covered with a nanoporous layer with a highly charged surface capable of attracting protons from water. When immersed in water, protons are drawn to the negatively charged surface of the nanostructure, forming an electrical double layer (EDL). Evaporation caused by increased temperature drives water to flow from this immersed region to the non-immersed region via capillary action. This flow creates an asymmetry of proton densities, causing a potential difference along the flow, known as the streaming potential, which generates electricity.

The proposed device utilizes waste cotton integrated with Triton X-100 and PPy, collectively termed CPT, as the nanoporous layer. This layer is placed in a cylindrical tube with corrosion-resistant aluminum electrodes at both ends, part of which is immersed in water. The black color of PPy enhances light absorption and evaporation, while Triton X-100 induces a high surface charge in the EDL, facilitating high voltage generation. This design allows electricity generation simply by shining light on the device.

Testing revealed that the device can generate a maximum voltage of 0.42 Volts and 16-20 microamperes of current under infrared light. As a fire-sensing device, it responds within 5-10 seconds. Furthermore, it maintained excellent stability over 28 days of continuous testing, with no corrosion or degradation in performance, indicating long-term viability. It also performed robustly under varying environments.

"This is the first demonstration of using a hydrovoltaic system in a fire sensing application," notes Prof. Hwang. "Our HV system has the potential to be a sustainable power source for various sensor systems, such as health and environmental monitoring systems that require uninterrupted operation."

Reference

Authors: Sujith Lal, Sudip K. Batabyal, Ergang Wang, Byungil Hwang

Title of original paper: Photo-sensitive hydrovoltaic energy harvester with fire-sensing functionality

Journal: Chemical Engineering Journal

DOI: https://doi.org/10.1016/j.cej.2025.159281 

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SOURCE Chung-Ang University