The need for alternative energy sources is a very real problem in the world today. New approaches using nano-scale technology has become a topic of interest and promises great potential in solving the energy problem. First in this thesis, we explore the history behind the development of nanofluidic-based electrokinetic energy conversion and compare it to other small-scale energy conversion technologies. Next, a theoretical and experimental study of nanofluidic conversion efficiencies are presented; showing the progression of the field towards a usable and practical solution. We derive a theoretical model of cylindrical pores for nanofluidic energy conversion and compare this to experimental data using pnc-Si membranes.

Specifically, I derive fluid flow in a nanochannel using cylindrical coordinates coupled to the classic combination of the Navier-Stokes equation and the Poisson Boltzmann equation which contains the electrical body force term. We use a monovalent symmetric electrolyte, the Debye-Huckel approximation and the small angle approximation to derive streaming current, streaming potential, and efficiency. This model will serve as the basis to design and guide our experimental results.

Next, a detailed study is presented on the development of the experimental set-up; including design iterations and the experimental procedure using the final design. In the final design, pnc-Si Membranes are used as the substrate of interest. This membrane offers regularly formed 50 nm sized pores with a thickness of 30 nm and offers low flow impedance due to its small thickness and regular geometry. Multiple pores give a proportionally increased power output compared to a single channel. We drive 1 mM--100 mM concentration KCl electrolyte solutions through pnc-Si membranes by applied mechanical pressures, the output of electrical currents were measured and recorded.

We obtained currents in the nano-amp range and compared our experimental results to those derived theoretically. Discrepancies between the two can be explained by concentration polarization due to ion/charge built-up on the pnc-Si membrane, polarization of the material itself, and high zeta potentials originally not accounted for in the theoretical model.