Power Extraction from Pico Hydro Turbines Installed in Water Pipelines

Abstract

A pico hydro system is a renewable energy production technology for electric power generation under 5 kW. It can be applied in remote areas with limited power resources. Given the importance of considering alternate renewable energy, this study fabricated and compared experimentally and numerically the three types of pico hydro turbines—Francis, Pelton, and Kaplan—which operate under the same working conditions. The study is applicable to residential buildings generating a small amount of power as an alternative electrical energy source. This small amount of power could light some bulbs or move an elevator if it is stuck during a power cut. It also provides power to apparatuses responsible for monitoring water conditions in a water distribution network. The experimental results validated the numerical investigations with reasonable agreement. The maximum extracted mechanical power was 680, 830, and 540 W with a maximum efficiency of 72%, 73%, and 68% with the Kaplan, Francis, and Pelton pico turbines, respectively. A control circuit was integrated into the studied system to select the operation between the investigated pico turbines according to the available water flow rate and applied load. The maximum output power ranged from 960 to 1,250 W when Kaplan and Francis pico turbines were activated simultaneously. Depending on the sensed flow rates, the control circuit was programmed to activate or deactivate the corresponding on/off valves controlling the selection between pico turbine operations. The maximum shaft speed of the implemented hydro pico turbines reached 200, 300, and 200 rpm, and the torque reached 35, 28, and 45 Nm for Kaplan, Francis, and Pelton pico turbines, respectively. These pico turbines were coupled with small synchronous generators, and the highest output voltage was 27.5 V at a speed of 300 rpm from the Francis pico turbine.