A groundbreaking study reveals how water’s interaction with surfaces produces electrical charges, highlighting implications for safety and energy storage.
Australian researchers have made a significant breakthrough in the understanding of how water generates electrical charges during movement across surfaces. The findings, published in the journal Physical Review Letters, stem from collaborative efforts between RMIT University and the University of Melbourne, led by a team comprising Dr Joe Berry, Dr Peter Sherrell, and Professor Amanda Ellis.
The researchers observed a phenomenon known as “stick-slip” motion, which occurs when a water droplet adheres to a rough or uneven surface. As the force builds up due to the droplet being stuck, it eventually “jumps or slips” past the obstacle, resulting in an irreversible electrical charge. This charge has been found to be up to ten times stronger than previously recorded when water transitions from wet to dry conditions, illustrating a newfound level of electrification when water initially contacts a surface.
Dr Peter Sherrell, who focuses on capturing ambient energy as part of his research at RMIT’s School of Science, commented on the common observations people make regarding raindrops falling on surfaces, stating, “Most people would observe that rainwater drips down a window or a car windscreen in a haphazard way, but would be unaware that it generates a tiny bit of electrical charge.” He explained that prior understanding of this charging phenomenon was limited to the transition from wet to dry, while their study reveals that significant charge also develops when transitioning from dry to wet conditions.
The researchers noted the importance of understanding charge generation as it relates to safety, particularly in contexts where flammable liquids are involved. Dr Joe Berry, an expert in fluid dynamics and associated with the University of Melbourne’s Department of Chemical Engineering, emphasised the potential dangers posed by electric shocks in fuel containers. “Understanding how and why electric charge is generated during the flow of liquids over surfaces is important as we start to adopt the new renewable flammable fuels required for a transition to net zero,” he said. Berry further elaborated that strategies currently in place for reducing charge build-up with existing fuels might prove ineffective with newer renewable fuels, highlighting the necessity for innovative approaches to manage this phenomenon.
The research team specifically examined the interaction between water and polytetrafluoroethylene (PTFE), commonly known for its use in Teflon. This foundational work sets the stage for potential advancements in surface design that may lead to safer fuels and improved energy storage systems. Future investigations will explore the stick-slip motion with a variety of liquids and surface materials, enabling a broader understanding of charge generation applicable to various commercial prospects.
Dr Sherrell remarked on the implications of the study for safety in fluid handling systems, particularly in the storage and transport of hydrogen and ammonia, stating, “We plan to study where stick-slip motion can affect the safety design of fluid handling systems, as well as methods to recover electricity and speed up charging from liquid motion in energy storage devices.” The researchers are keen to collaborate with industry partners to translate their findings into viable commercial technologies, which could hold significant relevance in a range of applications aimed at advancing energy solutions in the context of climate technology.
