Markets, TLUDs, and Peanuts

Hello friends back home! Though we are quickly nearing the end of our time here in Tanzania, work with the partners has been keeping us just as busy as ever. With just one more week left on the trip itinerary, we are scurrying back and forth every day to ensure that each group is in a good place briquetting-wise before our departure March 8th. Continuing on from the last blog post, we’ve attended another market session with the women’s group at EMORG, returned to Bernard’s shop to make adjustments to the small-scale demonstration TLUD carbonizer, and observed another pressing session with Violet Ayoub at the Vision for Youth production site.

On Wednesday, Sammie and I took our second trip to the weekly Kisongo marketplace near EMORG, where the chairwoman and two other members were continuing to market their charcoal briquettes. Despite not having purchased one of the traditional counter-weight massing scales yet for the group, we were still willing to lend our digital electronic scale for selling purposes. However, the women were adamant that this would dissuade customers and hurt sales since the latter was more foreign and less trusted. Instead, to our pleasant surprise, the chairwoman whipped out a spare scale from her storage just like the one on display in her shop. With equipment in tow, we took the 5 minute walk to the marketplace and set the supplies on an unoccupied patch of the market across from the lump charcoal sellers. Once there, the briquettes generated a lot of attention; waves of 4-6 people at a time would come and talk to the women enthusiastically about the manufacturing process. In between waves, two women took turns taking a sample of 5 briquettes in their hands and walking through the marketplace looking for potential customers. Despite the hullabaloo, only a few people actually purchased the briquettes, which were being sold again at 1,000 TSH per kg. Curious, we asked one of the lump charcoal vendors nearby if I could determine the mass of the two bucket offerings of charcoal available (instead of a mass basis, lump charcoal is traditionally sold in buckets). What we found was that a small bucket (containing about 1.8 kg of charcoal) was selling for around 800 TSH per kg, while the large bucket (containing about 7 kg of charcoal) was selling for around 700 TSH per kg. According to work done by the Legacy Foundation, briquettes should be priced below other competing fuels like charcoal to assuage the novelty and uncertainty factor associated with an unknown product, which didn’t bode well with the women’s current marketing strategy. At the end of an hour and a half when the women decided to pack up for the day, they had sold 6 kg of briquettes. Since the women can generally produce ~9 kg of briquettes per week at an average cost of ~600 TSH per kg, it may be worth investigating whether they can decrease the price to sell at least a week’s production each time they visit.

On Thursday, Anna and I went back to Bernard’s shop to further modify the small TLUD carbonizer based on the feedback from our initial burn. Adjustments included adding a separate afterburner piece with the mixing tabs pioneered by previous iterations of the loose biomass stove to provide more secondary air, knocking off the stove legs to allow the stove bottom to rest firmly on the ground to cut off primary air during the quenching phase, and using a piece of sheet metal as a lid to cover the top of the kiln and exclude air entering there during the quenching phase. After confirming the 5:1 ratio of cross-sectional area devoted to entering secondary air and primary air, we also decided to block half of the primary air holes with mud during actual operation. Our second run with dried sticks and kindling leaves proved more successful, burning more cleanly during the active phase and with a longer duration. However, when we transitioned to the quenching phase, we noticed that our lid was not appropriately air tight, so a lot of gas was escaping through the top and making the surrounding environment particularly unpleasant. After a 20 minute anaerobic period, we quenched the system with water and observed the yield. Many of the sticks that we had collected initially were of variable size, and in particular, cross sectional area. Consequently, while many of the thinner sticks were carbonized all the way through, the thicker sticks were only carbonized on the surface while the woody innards were merely torrified. Although a full scale operation should focus on carbonizing loose biomass, current experimentation has highlighted the importance of making the initial feedstock as uniform in composition as possible.

Finally on Friday, Peter and I took a trip to visit the Vision for Youth briquetting site, where we met with Violet Ayoub and three of the other members. To start, we talked about the BLSD kiln that was still running from when they loaded it 24 hours prior. They observed that the kiln was now taking longer than a day to carbonize a batch of material, and the material inside was turning into ash near the primary air holes and remaining uncarbonized over the secondary air channel. Violet recognized that the ash production was a necessary consequence of the partial air injection that is required to fuel initial combustion; however, the asymmetrical distribution of heat is proving to be a significant challenge both in terms of material conversion and operating time. After resealing the kiln, Peter talked to Violet about the small-scale TLUD that DHE has currently been investigating based on the larger oil-drum TLUDs pushed by ARTI in Dar es Salaam. We also got to observe another briquetting session with Violet. We watched the sifting process, which went relatively quickly since grinding wasn’t necessary for the torrified sawdust. The Vision for Youth team also experimented with wheat flour in their binder porridge, which worked reasonably well. With Violet leading the mixing, the slurry was also less binder-heavy than before. Pressing still proved somewhat awkward with the unusual way that material was loaded into the molds; however, we anticipate that the EMORG women’s group will have a lot to share in this regard as collaboration continues to develop. On a side note, we also enjoyed an amusing, mutual misunderstanding at one point. Violet in particular was excited about the prospect of using “groundnut” husk as a feedstock for the kiln because it is not usually fed to livestock. However, we had no idea what groundnut was, and took our fair attempts at guessing. Not walnut, not cashew, not pistachio. It was only after being shown a picture that we realized that they were talking about the peanut. It just goes to show that biomass by any other name burns just the same.

The Boys Venture to Dar es Salaam

Jambo friends!

Peter and I traveled to Dar es Salaam this past Tuesday, February 4th. After an hour long taxi ride, we became well acquainted with the city’s traffic-jammed streets filled with vendors weaving between trapped vehicles and peddling everything from peanuts to giant stuffed animals to the unhappy drivers. Eventually, we made it to the Safari Inn, where we established basecamp (and enjoyed the luxury of consistent air conditioning!) for the next three days.

The next day, we got up bright and early to catch our taxi to the University of Dar to meet Dr. Rajabu, a senior lecturer in the energy engineering department and longtime collaborator with DHE since the rocket stove project. There, we also got to meet Christian “Rui” Lohri, a researcher from the Swiss Federal Institute of Aquatic Science and Technology, who was serving as a co-advisor for two of Dr. Rajabu’s master students, Adam and Elia.  Despite struggling to find the Engineering College (our taxi driver, Salim, had to ask the local residents for directions), we arrived just in time to sit in on their weekly project meeting.

For their master’s work, both students are focused on developing low-cost processors for the drying and carbonization steps of converting waste biomass into charcoal. Adam’s project is a solar powered biomass dryer that uses a solar collector to heat air being drawn through a drying rack by an electric-powered fan. The solar collector also has an insert for a charcoal stove so that air can be heated during cloudy days. Elia’s project is a carbonizer made of a brick and a rotatable oil drum. Basically the rotating mechanism makes the process more efficient by using the produced pyrolysis gases to make the process self-sustaining.

After the project meeting, we had a quick lunch before we hopped into Dr. Rajabu’s car to take a bumpy road trip through Dar’s mountainous back-roads to visit several of the briquetting sites in the city. The first was a technology farm run by Tatedo (Tanzania Traditional Energy Development and Environment Organization) showcasing several batch carbonizers including dirt mounds and large scale brick-and-oil drum retorts, greenhouse biomass driers, and motorized briquetting processors such as a briquette extruder, and “pillow case” briquette press. Afterwards, we stopped by ARTI (Appropriate Rural Technology Institute) Energy’s Tanzania headquarters, where we got to see their oil drum TLUD carbonizers (essentially big scale versions of the demonstration TLUD on campus), and their hand-powered briquette extruders. To top off the visit, we talked with the executive director, Nachiket W. Potnis, and one of the program officers about their business model. ARTI expects to produce and sell 4000 tons of charcoal by the end of the year! It’s exciting to see at these places how charcoal briquetting can be successful and make an impact at a large scale.