Converting waste heat into electrical energy in ionic nanofluidic membranes
Creators: name: Nedrygailov, Ievgen
name: Rahme, Kamil
name: Ashokan, Anjali
name: Ranjani Palanisamy, Rupa
name: Holmes, Justin
name: Biswas, Subhajit
Publisher: name: Zenodo
Year: 2022
Subjects: energy harvesting
waste heat
waste heat recovery
nanochannels
nanofluidics
electrochemistry
ion intercalation
Seebeck coefficient

description: <strong>Abstract:</strong> Waste heat energy discharged into the atmosphere is one of the largest sources of clean, fuel-free and inexpensive energy available. Although technologies such as thermoelectric and thermo-electrochemical cells have been around for a long time, there is still no environmentally sustainable and efficient technology platform available for viable harvesting of low-grade waste heat. The central aim of our project (TRANSLATE) is to develop a nanofluidic platform technology based on large ion flux in nanochannels under a thermal gradient. This technology utilises Earth-abundant materials such as anodic aluminum oxide (AAO) and cellulose membranes for the development of a versatile and sustainable energy harvesting and storage platform. This presentation will provide an overview of the project on low-grade waste heat harvesting in ionic nanofluidic membranes. A key enabler for achieving greater waste heat to electrical energy conversion efficiencies is the overlap of electric double layers (EDLs) in very narrow channels. These overlapping EDLs cause a surge of ions (ion flux) into the ‘hot entrances’ of the nanochannels resulting in an enhanced thermovoltage, <em>i.e. </em>high waste heat conversion. The nanochannels with a diameter of ~10 nm and a length ranging from a few micrometers to several millimeters are created by two-stage aluminum anodization (for AAO), chemical treatment of natural wood (for cellulose). To increase the charge density, the surface of the nanochannels is functionalized, which leads to the appearance of overlapping EDL. We will present initial experimental results with aqueous electrolytes (KCl, NaCl etc.) that are capable of converting low-grade heat with thermopowers up to 1–3 mV/K, which is higher than that of conventional solid-state thermoelectric converters. Variation of the geometric parameters of the nanochannels, the type and concentration of the electrolyte, as well as the surface charge density of the nanochannels can result in a much higher ionic thermovoltage. With such a high thermopower, ionic nanofluidic membranes can be a game changer in the field of thermoelectric power conversion. <strong>Additional Information:</strong> Dr Subhajit Biswas presented at the HZDR NanoNet+ workshop on 4-6 October 2022 in Görlitz, Germany. TRANSLATE is a €3.4 million EU-funded research project that aims to develop a new nanofluidic platform technology to effectively convert waste heat to electricity. This technology has the potential to improve the energy efficiency of many devices and systems, and provide a radically new zero-emission power source. The TRANSLATE project has received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement number 964251, for the action of 'The Recycling of waste heat through the Application of Nanofluidic ChannelS: Advances in the Conversion of Thermal to Electrical energy’. More information can be be found on the TRANSLATE project website: https://translate-energy.eu/