Batteries can run flat quickly in remote locations and where device space is limited. Solar panels need proper mounting locations and only work during the day with good sunlight. While running water is a obvious source of energy, there exist are no open source, low cost solution that can be adapted to the individual application’s requirements.
The aim is to develop an open source hydrokinetic generator that meets the following requirements:
- Minimum part count
- As many parts as possible should be 3D printable
- All other parts should be commonly available
- The design should be scalable and adaptable to different scenarios and power requirements
I have settled on a Savonius type turbine for this system for this project. Although it is normally used as a wind turbine, it also works well in water
The advantages of Savonius turbine are:
- Simple design: A basic Savonius rotor consists of 2 “scoops” around a shaft
- Sturdy: The design lends itself well to 3D printing and should be able to handle the moderate impact of debris floating downstream, better than any turbine design with thin individual blades
- High torque: The Savonius rotor can still function in relatively slow flowing water, and it delivers relatively high torque
- Scalable: The length and diameter of the rotor can easily be scaled up and down
- Adaptable: It function both vertically and horizontally, fully or half submerged
- Works in shallow water: With the shaft oriented horizontally the turbine can extract power from very shallow stream and canals
The main disadvantage of the Savonius rotor is that somewhat inefficient compared to other turbine designs, however the advantages mentioned above should make up for this.
The rotor wil be connector via a speed increasing gearing to a brushless generator. I have decided on a brushless generator (motor) because it will be more reliable for long term use because there are no brushes to wear out. Ideally a commonly available hobby RC brushless motor will be used.
The rotor will be mounted to a waterproof housing which will contain the gearbox and generator.