Sun Yajuan, Huang Xu, Soh Siowling
Department of Chemical and Biomolecular Engineering , National University of Singapore , 4 Engineering Drive 4 , Singapore 117585 , Singapore . Email:
Chem Sci. 2015 Jun 1;6(6):3347-3353. doi: 10.1039/c5sc00473j. Epub 2015 Mar 26.
When a fluid comes into contact with a solid surface, charge separates at the interface. This study describes a method that harvests the gravitational energy of water-available in abundance naturally, such as in rain and rivers-through the separation of charge at the interface. Essentially, it is found that water can be charged by flowing it across a solid surface under its own weight; thus, a continuous flow of water can produce a constant supply of power. After optimizing the system, a power of up to ∼170 μW (per Teflon tube of 2 mm in diameter) can be generated. The efficiency, defined as the energy generated by the system over the gravitational energy that the water losses, can reach up to ∼3-4%. In order to generate a continuous stream of positively-charged water, there should also be a constant production of negatively-charged species in the system. Experimental results suggest that the negative charge transfers constantly to the atmosphere due to dielectric breakdown of air. With regards to applications related to high electrical potential of water droplets, the amount of charge generated in a single water droplet is found to be equivalent to that produced by charging the water droplet with a high-voltage power supply operated at ∼5 kV. In general, the energy generated is clean, renewable, and technically simple and inexpensive to produce.
当流体与固体表面接触时，电荷会在界面处分离。本研究描述了一种通过界面处电荷分离来收集自然中大量存在的水（如雨水和河流中的水）的重力能的方法。从本质上讲，研究发现水在自身重力作用下流过固体表面时会带电；因此，水的持续流动可以产生持续的电力供应。优化系统后，可产生高达约170微瓦的功率（每根直径2毫米的聚四氟乙烯管）。效率定义为系统产生的能量与水损失的重力能之比，可达约3% - 4%。为了产生连续的带正电水流，系统中还应不断产生带负电的物质。实验结果表明，由于空气的介电击穿，负电荷不断转移到大气中。关于与水滴高电势相关的应用，发现单个水滴产生的电荷量与用约5千伏运行的高压电源给水滴充电产生的电荷量相当。一般来说，产生的能量清洁、可再生，且在技术上简单、生产成本低。
