Volume 11. Number 1. 1-17 APRIL 2022 Jurnal ilmiah pendidikan fisika Al-Biruni https://ejournal.radenintan.ac.id/index.php/al-biruni/index DOI: 10.24042/jipfalbiruni.v11i1.10060 e-ISSN: 2503-023X P-ISSN: 2303-1832 How to cite Suhartono, S., Rudianto, R., Fatmawati, S., & Aziz, S. (2022). The performances of undershot waterwheel with butterfly-shaped blades and the radius of grasshopper's elbow: The utilization efforts for river electrical energy potential. Jurnal ilmiah pendidikan fisika Al-Biruni, 11(1), 1-17. The performances of undershot waterwheel with butterfly-shaped blades and the radius of grasshopper's elbow: The utilization efforts for river electrical energy potential Suhartono 1* , Rahmad Rudianto 2 , Sri Fatmawati 3 , Saiful Azis 4 1, 2, 3, 4 Insitut Agama Islam Negeri Palangkaraya, Kalimantan Tengah, Indonesia *Corresponding Address: suhartono@iain-palangkaraya.ac.id Article Info ABSTRACT Article history: Received: October 16, 2021 Accepted: March 12, 2022 Published: April 29, 2022 Based on the amount of discharge or current, the river flows in Central Kalimantan have the potential to produce electrical energy. The purposes of this study were to design an undershot type of floating waterwheel and to test the effective bending angle at the radius of the grasshopper elbow in producing the most optimum power. This research uses experimental methods. The tools used are: mobile phone, multimeter, the gate of light, timer counter, flow rate, and the dimensions of the waterwheel diameter is 6 meters. Grasshopper angles vary from 0°, 30°, 45°, 60 o, and 90° with a submerged blade depth of 0.24 m. The results showed that the undershot waterwheel with a flexible pinwheel (like a grasshopper's elbow) produced a faster and more effective rotation than a wheel with a fixed pinwheel and blades. Because the waterwheel has a flexible pinwheel and the butterfly blades experience little resistance when moving in water, the wheel generates more electrical energy than a wheel with fixed pinwheels and blades. At the angle of bending of the radius of the grasshopper blade 30º with the butterfly blade, it produces more optimal electrical energy than angles 0°, 45°, 60 o , and 90°. Suggestions for further research are to test the waterwheel in weak and medium current rivers. Keywords: Butterfly blade; Grasshopper elbow; Pico hydro; Undershot; Waterwheel. © 2022 Physics Education Department, UIN Raden Intan Lampung, Indonesia. INTRODUCTION The utilization of renewable energy sources is the right alternative to overcome the limited access to electricity in Indonesia, especially in remote community areas (Warjito et al., 2018). The largest use of renewable energy sources and is projected to increase is electricity sources originating from hydropower Fields(Faria & Jaramillo, 2017; Kougias et al., 2019; Manzano- Agugliaro et al., 2017; Pérez-Sánchez et al., 2017; Punys et al., 2017; Punys et al., 2019). One of the efforts to deal with a crisis in the field of electrical energy is to develop a type of small-scale hydroelectric power plant, pico hydro as an alternative way to utilize natural energy in the form of flowing water and as a way to protect the environment and preserve it (Arias-Gaviria et al., 2017; Brykała & Podgórski, 2020; Krajačić et al., 2018; Nishi et al., 2015; Quaranta et al., 2017; Quaranta et al., 2020; Quaranta & Revelli, 2018; Quaranta & Wolter, 2021). Hydropower offers advantages over fossil fuels because it uses water as a renewable energy source and a sustainable energy supply ( Ali & Kumar, 2017; Masud & Suwa, 2018; Zhou et al., 2019). Pico hydro is a type of hydroelectric power plant that produces electricity with an output power of less than 5 kW. Small-scale hydropower plants are receiving attention because of their high availability, suitable construction sites, and less impact on environmental damage (Balkhair & Rahman, 2017; McManamay et al., 2020; Nishi et al., 2020; Quaranta &