Collaborative Research: Enhanced electricity generation through liquid flow over durable slippery Surfaces

Michigan State University, East Lansing MI

Investigators

Abstract

Efficient hydropower technologies support national prosperity and energy security by providing a renewable energy source and reducing greenhouse gas emissions. Traditional hydropower technologies convert the kinetic energy of falling water to electricity using dams and bulky electromagnetic generators. Although hydropower is a renewable energy source, traditional approaches often come with adverse environmental impacts and poor power efficiency. Notably, electricity can also be generated when liquid flows over a surface, and the resulting electricity can be harvested without using dams or electromagnetic generators. Generating hydropower via liquid flow over a surface is a versatile approach that would enable the harvesting of energy stored in various forms across the global water cycle (e.g., water flow, natural evaporation, raindrops, and ocean waves). However, such energy generation approaches do not yet yield the desired voltage output. To increase the generated electricity when liquid flows over a surface, this project will examine the impact of the liquid-surface interfacial properties on performance; favorable properties include significant interface charges, small liquid moving friction, and being durable under flow. The generated knowledge related to liquid flow over novel engineered interfaces will transform key technologies in the sustainable generation of energy, clean water, and the design of biomedical devices. The investigators will conduct educational activities that focus on the professional development and participation of women in STEM, especially K-12 and undergraduate students, to train a diverse future engineering workforce. The overarching objective of this proposal is to discover new fundamentals of electrokinetics over engineered interfaces; this knowledge will be used to design a novel, durable slippery surface for improved electricity generation. Superhydrophobic surfaces are traditionally used to enhance energy conversion in electrokinetic flow by reducing interface friction. However, there are two significant challenges associated with using superhydrophobic surfaces for this purpose: the reduced interface charges due to non-charged liquid-air interfaces and the inferior durability of liquid-air interfaces under fluid flow. To address these challenges and achieve the overarching objective, an integrated experimental and computational approach will be employed to generate the necessary knowledge. Task 1 entails the experimental characterization of the streaming potential of electrokinetic flow over oil-filled slippery rough surfaces. This effort will lead to an understanding of the effects of liquid-oil interfaces and surface roughness on enhancing interface charges. Task 2 entails experimental characterization and direct numerical simulation of the liquid-oil interface stability and durability in flow under different oil properties and geometrical parameters of the surface texture. The influences of these control parameters on surface durability will be revealed. The insights gained through Tasks 1 and 2 will then be applied to design a durable slippery surface that will increase voltage generation by two orders of magnitude over that of using a solid or superhydrophobic surface. The novel durable slippery surface will transform the development of electrokinetic energy devices for myriad applications, ranging from small-scale in situ power sources for smart electronics to scaled-up energy systems for blue energy harvesting. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.