On Wednesday the 8th, we started early to meet with the Director of the Energy Development Division of EWSA in Kigali. He also responded positively to the idea of using small locally-built systems and encouraged us to continue our work.
From his previous time in Rwanda, Kyle knew of a young man who developed his own picohydroelectric system for his village, using homemade/salvaged parts and some serious dedication. His umudugudu (Shyira) is very remote, but given the nature of this trip it was definitely worthwhile seeing. Furthermore, we could use this site as a training site to teach site-surveying to the interns, and to get a practice run in before heading to the prospective communities.
So directly from the EWSA office, we went down to Nyabagogo (the main-but-not-centrally-located bus depot in Kigali) and took a bus to Musanze. After dropping some bags at a friends residence in Musanze, it was a bone-jarring and beautiful 1.5 hour moto ride up the mountains to Shyira. It didn’t help that it had rained in the morning either, and that parts of the road were under construction after landslides.
Once we arrived, we met the system designer, Christophe, and he led us up to the source of his waterpower — a pool at the bottom of a small waterfall (or ‘chute’, as seems to be the parlance here). From here, water flows through a dirt channel down through two earthen settling tanks before feeding into a final covered intake tank. From here, a four-section penstock (total length 19.5m) drops down to the powerhouse, where the flow drives an undershot homemade metal waterwheel (12 unevenly spaced sections). The waterwheel shaft is connected to a larger rotating plate of concrete, which connects to a bicycle hub at a 5:1 ratio. There are no control valves, and in the wet season the belt connecting the concrete shaft to the alternator falls off. The bicycle hub is attached to the alternator shaft, and the alternator itself is held to the floor by tightened rubber cords.
A Flow measurement was calculated by using the ‘float test’ combined with the dimensions of the channel:Channel Width: 25cm
Channel Height: 9.5cm
Float measurements: 2.0s, 2.4s, 2.8s, 2.4s over 170cm. (or, 170cm/2.4s = 0.71 m/s).
0.25m*0.095m*0.71m/s = 0.017 m^3/s.
Dropping over approximately 18m of head to the powerhouse.
The alternator has been wired to output single-phase 220V, and feeds through fuses out of the powerhouse to distribution poles to the village of Shyira and to a nearby school. In total, the system powers a cellphone charging kiosk, lighting for one office at the school, and CFLs at 20+ homes in Shyira. All homes/endpoints are individually fused as well.
Christophe’s Hydro-system
Christophe reports 800W in the dry season, and 1000W in the wet season, although I couldn’t verify this as when I planned to do electrical testing the system had to be taken down for brief maintenance. Those figures are in the ballpark for the loads he’s feeding, though.
All in all, pretty exciting system, especially considering he’s officially only educated to the equivalent of a 9th-grader (I restrain myself from writing a long aside on why students/individuals become more creative when they stop relying so deeply on a formal system to educate themselves, this will suffice
). We found a few issues that could be fixed by knowing more hydroelectric design theory, but the system has provided village power with some semblance of reliability for the past four years.
Christophe troubleshooting his alternator.
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