Off the Grid: Open Source and 3D
Democratic design ethos:
1) Form: making the world more beautiful.
2) Function: really making everyday life easier and more meaningful.
3) Quality: making everything last longer and age gracefully.
4) Sustainability: taking responsibility to have an improving impact on people and the planet.
5) Low price: making it truly affordable for the many.
This design is meant to help provide communities with access to energy via a bicycle powered generator. In this day and age electricity is a life changing resource and this design can be used to power: lights, radios/phones and charge car batteries. Access to electricity can help increase the standard of living for remote communities all over the world. The idea that is presented here is for a cheap and reliable alternative that uses cheap and/or recycled materials and requires no infrastructure or expensive installation.
The bicycle is an invention that has revolutionised human powered transport and is available all over the world even in some of the poorest communities. The concept is that the frame will allow any bike to attach and detach swiftly and without modification. There are many pedal powered generators out there but these require the complete repurpose of an existing bicycle. To poor communities it may be impractical to give up a bicycle to generate electricity so it is much more beneficial for the bike to be removable and usable day to day. Because of this the design is functional in providing electricity and in not damaging a bike.
To keep the price of materials low for poor communities the frame can be made entirely out of wood and screws, staple items that are readily available. The simple shape of the frame allows it to be built with as few tools as possible and customisable to fit any bike for communities who cannot access power tools and such. The form is beautiful not because it is complicated and flashy but because it is easy to build and use. Of course as this competition is about 3D printing many of the components can be 3D printed (connection to hold the bike wheel bolt, brackets to hold the alternator, and the fly wheel.) Again to reduce costs and thinking about sustainability we recycled an alternator from and old car to act as the generator. These can be found extremely cheaply or even free from scrapped cars.
Alternators produce 12v d/c, which is ideal for connecting directly to various small charging devices, or to large 12v batteries. To do this they require at least 2000 rpm and an initial voltage from a battery. To keep it functional and practical we expect the rider to cycle at a brisk but comfortable pace, so to get the revs a gearing system is required. Alternatively resistors can be used to create a lower operating speed. (http://alumni.media.mit.edu/~nathan/nepal/ghatta/alternator.html)
While the design calls for a wooden frame to be built, to make a prototype I simply used an old bike turbo – with thoughts to sustainability this is another part of the design that can be made from cheap second hand or recycled items. And in lieu of wood, I found some skis that were being thrown out and used them to screw everything together. 3D printing was used to make brackets to secure the bike and alternator to the frame and to make a flywheel. To give these components enough strength to stand up to their heavy use over time they were printed with a 4mm wall of 100% fill around the perimeter and to reduce print time and filament usage they had 20% infill fr the rest. This produces a high quality component. Through testing I decided i would need a flywheel with a diameter of 10cm to transfer the revs of the bike wheel and turbo axel into 1000 rpm. This would then translate to 2000 rpm on the alternator wheel as it had a 5cm diameter, doubling the revs of the flywheel. The effort required to produce those revs was not completely exhaustive, more or less an average comfortable cycling pace. However the generator might require an hour or two's use to generate the necessary electricity therefore, a more efficient gearing sytem wheels may be needed in the future.
Using the prototype I built, I managed to get 11 volts before the belt I was using came off the flywheel. More careful consideration must be taken to align the alternator to the flywheel and perhaps a bigger lip is needed to keep the belt on. However, overall the first test was a success and shows a proof of concept.