Kiln 2.0 and Improved Briquettes
I’m happy to report that all is well here in Leganga! We have made solid progress on the project and have also been continuing to enjoy our home here in Leganga. Recent discoveries include a great local restaurant, an interesting road that wanders through town, and some unfamiliar— but delicious— vegetables at the local market. The weather has been beautiful, with daily sightings of Mt. Meru and occasional views of the distant Mt. Kilimanjaro.
We’ve reached the midway point in the summer, and we look back on significant progress and enthusiastically look forward to more technical development, capacity building, and impact analysis in the coming month. Last Friday, we visited Vision for Youth’s proposed site for a briquette operation and discussed charcoal kilns, briquette presses, and possible worksite layouts. The work site has access to water, has adequate space, and is located close to their proposed market; all of these make their worksite seem very promising. In addition to the encouraging worksite, it was also fabulous to hear several of Vision for Youth’s creative ideas and to share our enthusiasm about briquetting.
After our weekend in Leganga, the team showed Bernard our charcoal kiln and briquette press technology. As a bit of background, Bernard is an inventor who worked with last summer’s Bioenergy travel team, and although we are no longer working on last summer’s stove design, Bernard had some incredible advice for us. He demonstrated an improved technique for mixing charcoal and binder: he showed how damp charcoal— as opposed to more water saturated charcoal— could be effectively mixed with very little cassava binder. With less cassava binder, the briquettes should be less smoky and will likely more efficient in combustion. Pressing damp charcoal also allows for a simplified briquette press; water holes or slits in the sides of the briquette mold are unnecessary, which will improve the durability of a mold. Using less cassava flour will reduce the expense of producing briquettes, especially in rural regions where cassava flour is less available. Bernard had some thoughts about our kiln design, which has led us to consider an underground counterpart to our current kiln. Underground pit kilns are fairly common, but a pit kiln could be modified using metal roofing— an easily accessible material— to create primary air holes and a chimney with secondary air, similar to our above ground kiln.
The team recently improved the kiln to increase charcoal yield. After identifying a large amount of ash in the combustion chamber after several kiln burns, we recognized that air was likely leaking into the kiln and allowing the biomass to completely combust. As a bit of background, the kiln aims to “carbonize” the biomass into charcoal in the absence of oxygen and to prevent complete combustion into ash. A likely culprit of the air leakage was the presence of cracks in the kiln’s mud mortar. So we re-mortared the outside seams and mortared the entire inside surface using an improved mortar: a mud and lime mixture. The lime successfully reduced mortar cracking, and appears to have created a tighter seal. The team also added two additional layers of brick to the walls of the kiln, which will increase the capacity of the kiln. Right now, the mortar is still drying, but we look forward to testing the kiln tomorrow!
And on Wednesday, we presented a batch of briquettes to EARD-CI for a cook test. We were able to successfully cook a pot of rice, but unfortunately the briquettes produced an excessive amount of smoke and did not burn as efficiently as anticipated. But we did not use the improved briquettes with less cassava. As I mentioned earlier, less cassava will reduce the amount of smoke and likely improve cooking efficiency. So we look forward to testing our improved briquettes once they have finished drying!
That’s all for now; we’ll update you again soon!