Evaluating domestic in-pipe turbines as energy harvesting devices for tropical climates

With volatility in the prices of fossil fuels along with their ongoing depletion and the urge to minimize greenhouse gas emissions, the focus of the energy sector is shifting towards renewable energy harvesting techniques. Although the power output is comparatively low for such techniques, their cumulative effectiveness and predictability make them suitable for small domestic applications. In tropical climates, harvesting rainwater and the kinetic energy associated with it has a huge potential. This research focuses on establishing the practicality of such systems over traditional wind and solar sources of renewable energy in dense urban environments. In addition, the categorization and applications are presented based on a literature review of in-pipe rainwater energy harvesting. This paper also reviews the mathematical parameters necessary for the design of such a system including the power, head, leakages, and flow characteristics. Investigation of using a dual-purpose pump as a turbine is also critically analyzed. Four important turbines appropriate for this application including Kaplan, Mitchel-Banki, Darrieus and Savonius are discussed along with their mathematical models. To establish a clear hypothesis on the practicality of each of the turbines, numerical simulations are also established and discussed. Finally, a practical in-pipe Kaplan turbine is experimentally tested at various water flowrates having a robust mobile design. Results show that up until the design flowrate limit the output parameters of voltage and current have a linear profile with predictable results, making such setup reliable and ideal for drains of domestic houses in tropical climates.