Hydropower Plant on a Chip: Frictionless Nanochannel Systems for Hydroelectric Power Generation

通过纳米级通道的水流可以产生被称为流电流的电能。然而，这种纳米尺度的流体动力流还没有在实际的能量制造系统中得到深入的研究，特别是由于通道壁上显著的摩擦能量损失导致的低能量转换效率。该奖项支持纳米流体动力流的基础研究，为开发具有高水电能量转换效率和输出功率的纳米流体能源制造系统奠定技术基础，具有实际应用意义。这种无摩擦的纳米流体能源制造系统就像“芯片上的水电站”一样，几乎没有能量损失，可以为小型自主传感器、它们的网络以及无需电池的移动/可穿戴设备供电。放大的系统（例如，这种芯片的阵列）可以进一步作为具有放大功率输出的大型系统的可靠发电站。从水（一种可持续/可再生资源）中获取能量，将使这种系统在不受环境条件影响的情况下发挥作用。与研究相结合的教育/推广活动将有助于培养下一代技术领导者，这是美国在全球经济中保持其在能源制造业领导地位的必要条件。本研究的目的是验证理论预测，即超疏水表面减少粘壁摩擦和显著滑移，可以增加纳米级通道流动中的离子流动电流，从而提高电动能量转换效率，可能接近100%，并且输出功率比目前的技术水平高出两个数量级。为了实现这一目标，将对在各种类型的超疏水表面上可配置的静电和水动力非均质边界条件进行数值参数化研究。通过耦合泊松-玻尔兹曼方程和纳维-斯托克斯方程，并采用基于Onsager互反关系的流体电路，计算得到的流动电流和流动特性。理论结果将在纳米流体实验中得到验证，通过测试不同电解质和流动条件下调节大小的超疏水纳米通道。理论和实验相结合的方法将揭示在具有非均匀边界条件的纳米通道系统中，电流体动力和动力学变量之间关系的新知识，这些变量对电动力发电至关重要。

Water flow through nanoscale channels can create electric power called streaming current. However, such nanoscale hydrodynamic flows have not yet been intensively investigated for practical energy manufacturing systems, particularly due to their low energy conversion efficiency resulting from significant frictional energy loss at the channel walls. This award supports fundamental research on such nanoscale hydrodynamic flows to lay the technical foundation for the development of nanofluidic energy manufacturing systems with high hydroelectric energy conversion efficiency and output power that are meaningful for real applications. Working as a "hydropower plant on a chip" with virtually little energy loss, the frictionless nanofluidic energy manufacturing systems can power small autonomous sensors, their networks, and mobile/wearable devices without batteries. Scaled-up systems (e.g., arrays of such chips) can further serve as reliable power stations for large systems with amplified power output. Scavenging energy from water, a sustainable/renewable resource, will enable such systems to be functional with little influence by ambient conditions. The integrated educational/outreach activities with research will help to prepare the next generation of technology leaders, a necessity for the U.S. to maintain its leadership role in energy manufacturing in a global economy. The objective of this research is to verify the theoretical prediction that a superhydrophobic surface reducing viscous wall friction with significant slip can increase ionic streaming current in nanoscale channel flow and consequently the electrokinetic energy conversion efficiency, potentially close to 100%, and also the output power up to a level two orders of magnitude higher than the current state of the art. To achieve this objective, a parametric study will be performed numerically for the electrostatically and hydrodynamically heterogeneous boundary conditions configurable on various types of superhydrophobic surfaces. The resulting streaming current and flow properties will be computed by coupling the Poisson-Boltzmann and the Navier-Stokes equations and employing the fluidic circuitry based on Onsager reciprocal relations. The theoretical results will then be verified with nanofluidic experiments by testing superhydrophobic nanochannels of regulated sizes for varying electrolytes and flow conditions. The combined theoretical and experimental approaches will reveal the new knowledge of the correlations between the electro-hydrodynamic and -kinetic variables critical for the electrokinetic power generation in nanochannel systems with heterogeneous boundary conditions.