Researchers at the Laboratory of Nanoscience for Energy Technologies (LNET) have discovered a new way to harvest energy from the evaporation of fluids using nanoscale devices, according to the study, ‘Salinity-Dependent Interfacial Phenomena toward Hydrovoltaic Device Optimisation” by LNET Head of Laboratory of Nanoscience for Energy Technology, Giulia Tagliabue, and PHD student, Tarique Anwar.
Hydrovoltaic (HV) systems are an untapped energy source, and the technology is not yet well understood, the researchers say.
The study used silicon nanopillars to convert evaporation energy into electricity, testing and analysing the effect of factors such as the surface charge and geometry of the nanopillars, the properties of the liquid (fresh water and saltwater) and the electro-kinetic interactions between the ions and the nanopillars.
The previously held assumption that this process requires fresh water is false, the report says. The device still functioned even at high salt concentrations, as the ions stuck to the nanopillars and flipped the surface charge. “The chemical equilibrium for the surface charge of the nanodevice can be exploited to extend the operation of HV devices across the salinity scale. As the fluid ion concentration increases, so does the surface charge of the nanodevice. As a result, we can use larger fluid channels while working with higher-concentration fluids. This makes it easier to fabricate devices for use with tap or seawater as opposed to only purified water,” says Anwar.
Researchers believe there is a broad scope for applying this technology, with the potential to function in various temperatures, humidities, and without sunlight. They also see potential for the technology to be implemented in desalination systems. “Natural evaporation is used to drive desalination processes, as fresh water can be harvested from saltwater by condensing the vapour produced by an evaporative surface. Now, you could imagine using an HV system to produce clean water and harness electricity simultaneously,” said Anwar.
