Congratulations to DHE for having three papers published in Procedia Engineering this September!

Check out and download the papers here:

“Implementing Pico-hydropower Sites in Rural Rwanda”

“Targeting Briquetting as an Alternative Fuel Source in Tanzania”

“SafaPani: A House Electrocoagulation Arsenic Water Filter for Nepal and Other Developing Countries” 

If you’re interested in learning more about Procedia Engineering; the Humanitarian Technology: Science, Systems, and Global Impact 2014 (HumTech 2014); and the social impact that DHE’s colleagues are having around the world, check out the entire Volume 78 of Procedia Engineering

Congrats again to all involved and well done DHE!

Doing well and having fun in Kigoma!

Updates since the last blog post…

As it turned out, finding different sizes of barrels in Kigoma was a bit of challenge. The only available barrels were standard full sized barrels. This meant that the Kigoma TLUD would have to take on somewhat of a different design compared to our Arusha TLUD. Instead of using a narrow barrel as a chimney, a sheet of metal would have to be rolled into a chimney.

Along with Max (a JGI intern) as my translator, a JGI driver and his Toyota pickup truck, I went to see a guy working at a metal shop to have the TLUD kiln built (while Dvij was recovering from his bad stomach at the lodge). He said the kiln would take a day or two to finish. Strangely enough, this guy only had his hand tools to make the kiln with. No electric power tools at all! Despite this, after the two days, the kiln was finished. It was the most eloquently built kiln that I’ve seen to date in Tanzania. It has a one meter long chimney, longer than that of our Arusha kiln.

Finding the appropriate feedstock to carbonize in the kiln was an easier endeavor. There is a wood processing district about ten minute drive away from the town center where we managed to buy eight sacks full of saw dust for 1600 tsh each and two sacks of rice husks for even less than that.

Dvij and I found that running our new larger kiln was different to the smaller kilns in Arusha. The wood gas flame was much more vigorous and appeared to be ‘floating’ on top of the feedstock. Furthermore, each runs of the kiln was more consistent in terms of the char yield. We also found out that layering the bottom of the kiln with dry leaves and grass helped the bottom most layer of feedstock to char completely (which was an issue that we faced in Arusha).

Later in that week, we had a chance to visit two villages called Kalinzi and Simbo. Kalinzi was about 45 minutes away by car and Simbo was another 30 minutes by car from Kalinzi. Kalinzi is the region’s prominent producer of coffee while Simbo produces palm oil. We learnt that harvest of coffee occurs between August and October. We arrived just before the harvest season but there still were, literally, a mountain of coffee husks left from the previous year. The husks were free to take and local already used the husks to cook their food with. We realized here that there were big opportunities to run a sustainable briquetting operation. (We also found a rusty carcass of a rocket stove that we suspect is an artifact from previous DHE travel groups!)

In Simbo, we found a few small piles of palm fruit shells and fibers. Apparently, all the shells and fibers are burnt because there is no other use for them. The locals told us that burning these shells and fibers was a dirty process as palm oil does not burn cleanly.

In the following weeks, as the rest of our team members arrived from Arusha, we started doing demonstrations of our kiln and the briquetting process for a number of different communities.


We visited a village called Ilagala which is an hour away by car. Our original plan was to do a demonstration kiln run for a small group of people. However, as we started setting up the kiln, our demonstration run quickly became the subject of interest for the entire village. There were about 80 village elders, teens, and children who joined us in running the kiln and briquetting. Steffi and Max translated for us and handled the bombardment of questions from the villagers exceptionally well. The villagers were very curious about how the kiln worked, what kinds of feedstock could be used, and the performance of the briquettes. There were a few people who explicitly expressed their interests in building the kiln and we left them a copy of our kiln building manual.


We also held a demonstration session for the youths of Kividea (Kigoma Youth Development Association). These youths were high school aged young adults who were interested in production of alternative fuels. As we were showing the youths how to pack the kiln with feedstock, we realized that we did not bring enough of the coarse sawdust but had brought too much dense coffee husks. Initially, we were worried that the kiln might not run as well as because the denser layers would pose a significantly increase fluid resistance for the updraft of air through the feedstock. However, the kiln produced a typical yield of char (and we did not embarrass ourselves in front of all the youths). The youths were amazed by the fact that pressing the mixture of flour porridge and char produced briquettes and were eager to use the molds that we brought to pump out briquettes. The representative from Kividea who helped us to organize the occasion was also very impressed and enthusiastic about the entire process. He promised (yes, promised) us that he would build a kiln in a month or two when the organization had enough money and made us to promise him that we would email him our kiln building guide book.


Bye Arusha. Hello Kigoma!

After a sudden flight cancellation on Sunday, Dvij and I (Jun) made our two day long trip to Kigoma from Arusha via Dar es Salaam on Monday. We arrived on Tuesday morning in good shape and excited (despite that Dvij had lost his luggage for his second time in Tanzania). We are staying in Royal Prince Lodge which we have found to be somewhat of a lonely place compared to the EMORG volunteer house due to the single rooms. Food from the lodge restaurant is delicious and is worth waiting through the forty minute preparation time.

On Wednesday morning (after Dvij finally got his luggage back from Air Tanzania), we made our way to JGI in order to meet Mary, Shadrak, and Mtiti. JGI is about forty minutes away from the Lodge by foot and about ten minutes away by taxi. Our meeting started off with our presentation of 14X travel team’s work so far in Arusha and of our four partner organizations. The people from JGI were genuinely interested to know more about TLUD kilns and charcoal briquetting. We presented them with cost analysis of building (around 44,000 TSH) and running a TLUD kiln made from barrels. Mary particularly seemed to be impressed by the low cost of building a kiln, and that about one man-hour was enough to produce one kilogram of briquettes. However, she did note that some people may not be willing to use cassava flour as a binder because its price has recently increased.

Our meeting then progressed on to discussing what the 14X team could do here in Kigoma. We learnt from Mary that lump charcoal is made in villages and then transported to urban centers in Kigoma for sales and consumption while women in these villages use firewood as fuel. Although cooking is usually done outside or inside a separate building, the use of firewood is still poses a health threat to both the women and their children. As we see it, there is a need discourage the use of lump charcoal in urban centers and encourage women in villages to use alternatives to firewood (possibly charcoal briquettes). Furthermore, according to the people of JGI, there are a variety of feedstock easily available in Kigoma. These include coffee husks and banana leaves in high-land regions, palm tree fruit fibers (which are used for kindling fire as they burn easily), and sawdust. Corn husks, however, are difficult to find because they are fed to animals.

During our meeting, a number of different organizations/individuals were mentioned who we could work with. Students in Root & Shoots program, Kigoma Youth Development Association, various women’s groups, and forest monitors are potential partner groups based in Kigoma but more specific details will come later with more meetings.

On the way back from JGI to Royal Prince Lodge, Dvij and I looked around the town for barrels. However, we only managed to find full sized barrels which are much bigger than the barrel we have been using for our demonstration kilns back in Arusha. We have visited three different shops but smaller barrels were nowhere to be found. There is a possibility that we may have to make a full sized kiln and roll up a sheet metal to make a chimney instead of using narrower barrels.

Our tentative plan for this week is to explore the town and find appropriate building materials and sources of feedstock so that we can start assembling a demonstration kiln and run it. Tomorrow, JGI will be providing us with a driver who can take us around the town. Hopefully, we will find what we are looking for.

On the other hand, the other half of our group staying behind in Arusha has an exciting week ahead of them. They will be conducting input/output analysis of a TLUD kiln as well as testing our briquettes against lump charcoal that was purchased in a town market a few days ago by heating up vessels of water to gauge the thermal outputs. The group will be also consult Vision For Youth to help them build and run their own TLUD kilns.


P.S. No photos this week. The internet connection is very slow and unstable!!!

A Hybrid is Born

Day fifteen in Arusha starts with a quick breakfast of peanut butter and honey on toast and a little one on one football in the backyard with Philbert. The nyama choma (roast beef) from last night has taken Jun out. I admit I feel a little uneasy too but my tough Bombay tummy is holding up well. We are off to EMORG today with a new kiln design and there’s a lot to say about it but first let’s rewind one week to last Thursday.

We spent the morning running our two demonstration kilns (See Olivia’s Busy, Busy for a brief description of their designs) to try to figure out appropriate feedstock “recipes” for the kilns. Fine feedstock must be mixed with coarse feedstock in a proportion that allows for the passage of oxygen through the substrate but that is not so airy that the flame eats through the substrate, turning it to ash.

If a larger proportion of finer and/ or damper feedstock is used, the kiln will take a longer time to produce char. Burn times typically take between 15 and 25 minutes. After packing the kiln, we dribble around 20 ml of petrol on the feedstock (petrol costs 2500 Tsh per liter). The petrol allows for a big flame for the first minute or two of the burn, depending on how densely the feedstock has been packed, this flame disappears after two to five minutes and the kiln begins to emit a thick white gas which is damp to the touch suggesting a high water content. The energy to draw this water vapour out of the kiln comes from the embers in the feedstock and the pressure gradient induced by the natural draft of the chimney. This second phase of the run usually takes between 10 and 15 minutes. After most of the water has escaped from the feedstock, the flame shoots back up with dramatic bravura. At this point the chimney and adapter are removed and a damp wooden stick is used to make sure that the combustion is occurring evenly across the surface of the feedstock. Pockets of raw feedstock are mixed around into the flame to ensure that the action front is descending symmetrically across the face of the drum. After four to five minutes the kiln is quenched with water, the char is removed, inspected, dried out and weighed.


With a better understanding of the recipes that worked well, we set off to meet with the women’s group at EMORG to run a demonstration of the Takachar-inspired kiln with sawdust they had purchased from the local market in Kisongo. The women were impressed with the quality of the char and used it along with cassava flour to press out briquettes.  The press that EMORG is currently using to produce briquettes is not able to apply sufficient pressure onto the molds and so although we were hoping to test the briquettes we made using the char we produced last Thursday, we were informed a couple days ago that, in a calamitous turn of events, the briquettes crumbled before they dried.


Our pressing woes disappeared on Monday, with a trip to Vision for Youth. Our buddy Miguel from Johns Hopkins volunteering at V4Y purchased a G clamp to use as a press. The G clamp was tremendously successful in producing well-packed briquettes that showed no indication of crumbling before drying. We are looking forward to testing these briquettes over the next few days, and introducing the concept of using a G clamp to press briquettes to the women at EMORG later today.

Although the retort kiln described in Busy, Busy produced high quality char, it was psychologically off-putting that the material in the outer barrel would burn completely to ash. In response to this, we decided to combine both designs into a hybrid by attempting to produce char both inside and outside the retort. This was achieved by using the retort in the traditional TLUD design (with holes only in the bottom of the outer barrel for air to enter and none on the side to aid combustion) and packing the outer barrel as we otherwise would have with no retort. The little metal tubes shown below were placed in with the feedstock to help the action front descend symmetrically. The thought was that the tubes would serve as reservoirs of heat so that the pyrolysis wasn’t at the behest of the wind—if the flame moved to one side, the metal would retain heat in the other, continuing the pyrolysis until the flame invariably returned.


On Tuesday we built a new cylindrical retort to replace the box-shaped retort we had previously been using. We were hoping that the added dimension of symmetry would help the action front descend more evenly and char the material in the report more consistently. However, we found that the added volume of the cylindrical retort rendered it useless. Having more volume inside the retort means that more energy is required to pyrolyse the material inside. Most of this energy comes from the material in the outer barrel. There simply wasn’t enough material in the outer barrel with this new design to get the reaction off the ground. We thus reverted to using the box retort in the hybrid kiln. We are glad though that we built the cylindrical retort and discovered this restriction on the ratio between the cross sectional areas of the retort and the outer barrel – this is definitely valuable information to document.


We have done some preliminary measurements to calculate the yield of our current hybrid kiln design (how much char is produced for a certain mass of feedstock put into the kiln), we will hold on to that data for the time being, as it probably does not reflect the true potential of the kiln. We get better at running the kiln every day and want to try a few more iterations before we publish yield statistics for our design. At this point, the yield looks promising enough to support a profitable business model. Our main goal over the next few days is to iron out the details of a business model, so that we may present it to our partner organizations instead of presenting a product in isolation.

Finally, we get to yesterday when we met with DHE constact Mr. Sossy, an associate with a women’s group in Tumaini Center in Arusha. We set up a time to meet with the women’s group, which has produced briquettes in the past, to demonstrate the new kiln design. We hope the group shares Mr. Sossy’s enthusiasm to see the new kiln. More on this later!



Closing Time

Just kidding! It’s not quite closing time yet – we still have 3 days left! We’re in the wrap-up stages of our work here, but exciting things are still happening. In the last 3 days we’ve been able to meet with each of our 4 partners here; that might be unprecedented efficiency. Let me take you through it.

On Monday we made the trek out to Leganga where Lulu Vicoba is. We were joined by two of the leaders from Vision for Youth (both named Violet), as they continue to show their commitment to meeting the other briquetting groups in the area. This was the first time we got to observe Lulu Vicoba actually pressing briquettes, and they proved to be proficient in the process. It was also great to see the Violets from Vision for Youth being active in both learning about Lulu’s process and also sharing the knowledge they have. This information sharing was continued as Violet and Violet helped us share knowledge about how kilns work to carbonize biomass.

The action only picked up on Tuesday. First we had the privilege of meeting with Professor Karoli Njau at the Nelson Mandela African Institution of Science and Technology. We were thrilled to learn he has worked extensively with our friend Dr Rajabu at University of Dar es Salaam. He shared his knowledge about sources and alternative uses of waste in the area. The value of a type of waste in briquetting is determined by its competing uses. For example, vegetation such as banana leaves are valued here as food for livestock, whereas rice/coffee husks don’t have alternative uses so they can be valuable in charcoal briquetting.

We capped off the day by visiting Upendo. Upendo doesn’t usually briquette during the rainy season because of difficulty in collecting materials. This fact, combined with most of the women’s group being sick, resulted in only having one woman available to show us their process. But we overcame this difficulty and she showed us how they make doughnut shaped briquettes.

Finally, today we returned to EMORG with the intention of making some big sales at the market. But before we could do that, they surprised us with a party put on by our friends Didas and Troy. EMORG has been extremely helpful to us during our time here and we can’t thank them enough, from providing our housing to delivering for us when we’re in dire need of transportation. It was a nice chance to reflect on the last month and share some laughs with new friends. The good times continued when afterwards the women’s group sold over 10 kg of briquettes at the market!

Good Times at EMORG
Good Times at EMORG

(more pictures to come when we have better internet!)

Travel Team Keeps Grinding Away

Wow only 2 weeks left here in Arusha for the travel team! Big things are happening on the regular, and we have a couple things in particular that have happened since Sammie’s last post.

With the help of our friend Bernard and some skillful hands at his workshop, we finished the first prototype of a new charcoal grinder on Wednesday! While it still has room for improvement, it’s a big step toward relieving the women of the back-breaking work of grinding the charcoal with a mortar and pestle. We brought it to both Vision for Youth and EMORG on Thursday, and they were both grateful for its potential to improve the process. EMORG had a carpenter look at the design today and they should have a bigger version of it soon!

Sharing the grinder prototype with Vision for Youth
Sharing the grinder prototype with Vision for Youth

The excitement didn’t stop at the grinder for EMORG and Vision for Youth, though. Yesterday we got the leaders of the two groups to meet for the first time – the first of many we hope! Since we’re only here for another 2 weeks, it’s crucial that knowledge on briquetting can continue to be spread in Arusha after we leave. It’s exciting to see the different briquetting groups start to network in ways that will be mutually beneficial moving forward. The meeting went so well that EMORG invited the Vision for Youth leaders out to their workspace to see how their briquetting operation works. The meeting was in Swahili so we couldn’t understand much (Violet Ayoub from V4Y filled us in on the important things), but at the end I heard an enthusiastic “Karibuni” (welcome) several times from the EMORG chairwomen – always a good sign.

First meeting with Vision for Youth and EMORG together!
First meeting with Vision for Youth and EMORG together!

As for lifestyle updates, I’m basically a local now because I had to ride on the outside of a dala dala the other day – hanging on for dear life. It was a little scary especially because there was so much mud, but at least I had way more space for my head and knees than I usually do on the dala dalas! We’ve enjoyed making friends with the locals as well. Some highlights include the girls politely turning down a few marriage proposals and I got to teach some new friends how to throw a frisbee.

That’s all for now, but stay tuned!

Sammie makes a new friend
Sammie makes a new friend



This Week in DHE (2/5/13)

What’s going on this week in DHE?

Not sure how to answer? Thank heavens for our weekly updates!
Check out what’s up with your favorite project groups:

Marketing and Development continues to work on letters to the USAID and will soon be meeting with professors to seek funding from the National Science Foundation.  Also, DHE was just accepted to the second round of the 2013 CleanTech Challenge!

Biogas will continue daily monitoring of our bench scale food waste tests. At next week’s meeting, we will add material inlets and outlets to our 55 gallon digester.

This week the Bioenergy Project discussed Tanzanian cooking styles and fuel use. We watched an informative video from, and we encourage members to follow this link  to learn more about cooking styles in Tanzania. Remember to send in trip applications by 11:59pm on Wednesday, 2/6!

This week, Hydro split into Mechanical and Civil subgroups. The Mechanical group focused on ordering parts for a new turbine while the Civil group learned how to compute dimensions for open channel flow of a specified flow rate as well as the sizing of a settling tank. We also have been sand casting using our new manual bellows and are producing usable buckets. We look forward to making a turbine out of buckets cast using sand casting techniques we’ve developed.

Impact Analysis spent this week’s meeting discussing ways to assess briquetting and other Bioenergy initiatives on the ground in Tanzania. However, we also spent a good deal of time reflecting upon ways to assess DHE on an organizational level, considering impact by and upon all members involved. We were lucky enough to hear about past trips and evolving project goals from Annie and Kim, and will continue discussions and survey development next week.

Don’t forget to turn in your applications for travel! Apps due this Wednesday for Bioenergy and the following Wednesday for Hydro.