This past week, our team has been focusing on the development of a few major design iterations for exploration over the summer in Malaysia. The three main designs under consideration include a cone design, a "Tin Man" design, and a "Jolly Roger" Design. The team researched these designs over the course of the past week and have been compiling thorough documentation on the various designs. The Tin Man iteration was discussed very thoroughly. This design uses an external fuel source to virtually "bake" the biochar. Off gas is used to further th pyrolysis until complete. It takes gas from the bottom and can be considered as a batch system. This is similar to the Jolly Roger, which is another batch system. However, this system takes gas off the top and uses the feedstock as a source of fuel. In contrast, the Cone Design is not a batch system, and requires constant maintenance and monitoring to refill with feedstock and remove processed biochar. This would allow the user to burn as much feedstock as necessary in one trial, but would require more maintenance during operation. The team will be working this week to continue to develop fleshed out plans for these designs including a comprehensive materials list, budget and risk register for each moving forward. Over the summer, Latifah hopes to build and implement these designs with a farmer in Malaysia! More updates to come :)
Following last week's change of plans, the team spent this week reviewing our original design ideas and preparing for our midterm report. Adam in particular was very busy, crafting our new plan for the rest of the term, focused on preparing for a summer of testing in Malaysia.
For the next few weeks we will focus on reviewing our original design ideas and determining which ones could be adapted for testing by Latifah. From this we will produce a comprehensive budget for the summer work, and determine a plan for the summer.
From our original review of our winter quarter designs, we noticed that we had mainly focused on smaller designs that could easily be assembled for a quick prototyping process. However this summer we are focused more on a permanent, proof of concept design. Specifically our aim is to determine whether cacao pods can produce a biochar that can be used to help communities in some capacity, either as a fertilizer, water filter, or other use. With this in mind, we decided that it may be more useful to construct a larger scale converter that could be used to produce larger quantities of biochar through out the summer.
However Wenxi pointed out a number of obstacles that come with constructing a larger scale design. Specifically, a number of things that we had ignored as low risk, such as convection currents, even heating through out the material, and exhaust gases, become much more significant factors on a larger scale that need to be properly accounted for. With this in mind, we decided to split into two groups moving towards next week. The first group of four will look further into large scale designs and how to construct them. The second, smaller group will construct a rough budget for the summer that we can continue to edit as the term progresses.
Following up on last week’s research, our team continued looking into the accessibility of testing materials for water, soil, and biochar. With regards to water quality home testing kits, there are some testing kits available via Amazon that can test for toxic metals, volatile organic compounds, and coliform. However, these are expensive (~$350), and it did not seem productive to be using our budget to be testing local water quality whose results could possibly be obtained by our local utility provider or via websites. In addition, the water testing kits were missing testing for physical appearance/aesthetics, something that we had learned is valuable to look into when we researched Ghana’s current water quality. This is because people do not want to drink discolored water (even though its water quality may be up to standards). In terms of soil testing, there is a soil lab in Ghana that can perform toxicity tests of the soil at farms where we are planning to work at. However, it was brought up that there is no point in testing the soil right after applying biochar because we would need to wait for the full growth of cacao plants to see any noticeable differences in soil composition before and after biochar application. In terms of biochar testing, most of the toxicology tests can be done in a certified testing lab while utility tests can be done by ourselves.
Originally, we planned to purchase cost-friendly and reliable testing kits that the team could eventually bring to Ghana to measure our local water and soil quality in order to test the effectiveness of these kits, but one particular question came up among all of us: what are we expecting to find using these test kits? We would not have any benchmarks to compare to, especially because we have no access to site-specific water or soil samples from the farms we are hoping to deploy our biochar apparatus at. We also have not been able to produce biochar to test from the cacao husks that TCHO gave us due to COVID-19. This is further complicated by our lack of access to the Environmental Engineering labs in Y2E2; only critical researchers are allowed access to these labs during the pandemic, so we would not be able to compare our results with laboratory equipment.
Because of all the uncertainty regarding testing and sample accessibility, we decided that it would be more productive to instead focus our remaining weeks of the quarter on scaling up our design since Latifah recently connected with a chocolate farmer in Malaysia who is enthusiastic about trying biochar. Last quarter, we had conducted literature review of existing designs and prototyped a very small design using cans. However, in order for biochar application to be useful, a much more substantial amount needs to be produced, especially since there are a LOT of cacao husks during harvesting season. In the next five weeks of the quarter, we plan to create a more comprehensive design with specific material requirements, so that we can order to them to Malaysia for Latifah to begin prototyping.
After three weeks, the team’s morale is running heavy on the academic side and low on the emotional well-being (or perhaps I am being presumptuous and overdramatic); about half of us have decided to listen almost exclusively to up-beat music, as epitomized by Doja Cat’s “Boss Bitch”.
Debriefing on this week’s research topic (testing procedures, qualifications, etc), we found that the incredible amount of literature available on the subject meant that we only could do a very superficial pass on what notable organizations, namely the WHO and EPA, have suggested and implemented. Testing focuses on four major categories: chemical, radionucleic, biological, and aesthetic. Of these, the most pertinent to public health was biological, due to its association with the indicator organism E. coli and, consequently, the cholera toxin. When considering soil composition, basic tests measure the pH and available nutrients—sodium bicarbonate, potassium, phosphorus, sodium, and magnesium, most significantly. However, cadmium testing is an emerging issue in the cacao industry, and may be worth looking into. Fortunately, soil specifically used for cacao (and for agricultural purposes) depands predominantly on carbon nutrients, which biochar would be helpful in augmenting. In terms of biochar testing, predictably, we can refer to the International Biochar Initiative, and refer to the ratio between hydrogen and carbon to determine the carbon storage class, the fertilizer class, and particle size as a means of evaluating nutrient (and, to some extent, pathogen) retention.
Though our research was fairly exhaustive, it is, of course, incomplete and broad. For example, we need to scrutinize even more closely what biologic and chemical contaminants we should focus our attention. But even more pressing is the question of accessibility to tests. Given our distant locations and now even more limited access to labs and materials, we must decide which experimentation parameters we can compromise on, and which we can find proxies. Soil testing, therefore, is somewhat problematic, given that there is no standard format for lab tests, and the sample tests are not always provided in the website; the scarcity of information means that we may have to do additional testing or spend more time researching alternative tests.
On the whole, our extensive research phase has broadened our understanding of the context of Ghana and provided us with more insights on how to approach not just the use of biochar, but also on the complex nuances of the political climate and social parameters in which we would be working. Our design and previous thoughts were, as expected, flawed and limited, and we are starting to more deeply question things like: does our design need to be scaled up to be effective? How can we better correlate soil testing, water testing, and apparatus testing? And now in quarantine, how can we expect to proceed without access to our cacao husks, and to what extent can we say the soil and water samples from our local areas are sufficiently similar to that in Ghana?
As everyone finally got settled down and used to the whole new quarantine-lifestyle, our project has been making smooth progress according to our timeline. During the first week, everyone in the team did research around cultural and historical background in Ghana - topics include history of cacao farming in Ghanan, political history of Ghana, and cultural significance of cacao in Ghana. With decent amount of information collecting, reading, and rearranging, we developed a comprehensive report on each of the three topics.
During our weekly meeting, we shared our findings and sparkled new ideas that could lead to future development of the project. Some of our important findings include: 1) Cacao trade is monopolized by the government in Ghana, any trade no matter domestic or international has to go through COCOBOD; 2) Land right shift led to agricultural policies' change; 3) Cacao growing is labor-intensive, slavery and child-labor are unfortunately part of the play.
After the educative debrief session, we went on for reflection and finding gaps that needs further investigation. Some express their interests in finding the interplay between the government and the local farmers in the cacao economy, others saw the potential of using biochar as a cheaper alternative to fertilizers, helping farmers overcome the economic barrier.
Next week we will focus on the location background research in Ghana and move on to the topics that are more related to finding the user demand.
A lot has changed since our last post, largely due to the large historical moment that is currently occurring internationally. With the developments to COVID-19 in the United States, these shifts have led to Stanford Campus urging students to return home and a dispersal of our team around the world. For the first couple of weeks since it was announced that Stanford Spring Quarter would be entirely remote, the team was working on settling down and returning home in a short period of time. Booking flights, packing, and saying goodbyes were cut short and had to be done in a timely manner.
After things had settled a bit for our team members, in late March, we had a check in call and discussed the best ways to proceed. The team was committed to our project, and we all wanted to continue with our investigation. Despite this dedication, our project work must take major shifts to accomodate the developments. Unfortunately, with the pods and their husks left on campus in the lab, there is limited access for the team to continue to develop our production apparatus. Additionally, with a remote platform, communication and collaboration have become more difficult.
Moving forward, we are focusing on streamlining our research process and creating a testing baseline, focusing on robust research within four main themes: cultural and historical background in Ghana, geographical context with regards to soil and water quality, in depth understanding of standard testing protocol of biochar, water, and soil, research into current testing practices, and practical and affordable testing systems for baseline studies. Over the first half of the quarter, the team will focus primarily on research to develop a strong baseline for investigation. The second half of the quarter will place an emphasis on testing, ordering tests to individuals' locations in order to start control/baseline testing for further comparison.
The TCHO Team is eager to continue our work and grateful for all that we have learned from this process. As we proceed, we are thinking critically about the timliness and relevance of our project for our stakeholders, as well as the relationships we have built with one another and our partners. We hope to continue to treat these relationships with utmost importance moving forward, keeping health and safety our top priority.
In the past two weeks, we have made a lot of progress towards our winter quarter goal of having an apparatus that produces biochar. Reflecting on what priorities are most practical for our first year of experimentation, we decided on prototyping a simple dual-chamber TLUD using recycled food cans (a 32 oz can (ex: quart-sized paint can), a 19 oz can (ex: Progresso soup can), and a 5 oz can (ex: tuna can)) that will use pyrolysis to convert the cacao husks into biochar. Pyrolysis is the thermal decomposition of biomass at high temperatures in the absence of oxygen, producing biochar. This simple design was inspired by Brian Zaro and was in line with our current most pressing project requirements that we’ve identified through research, including using cacao husks to make biochar and limiting particulate emissions of toxic syngas.
The TLUD is constructed with two concentric cylindrical containers and a riser (see figure from Week 6 blog post). The inner cylinder acts as the fuel chamber which has holes in the base and the bottom on the sides. These holes act as the primary air inlet to allow air to go inside the inner fuel chamber to initiate pyrolysis. There are also holes on the neck which serve as an inlet for secondary air to mix with syngas for complete combustion; this will limit the emissions of toxic syngas. The outer cylinder has holes near the bottom on the sides that act as the secondary air inlet. During combustion, air enters these holes via a natural air draft. The upward flow of heated gases causes a negative pressure (partial vacuum/suction) that draws new cooler air into the combustion zones to sustain the chemical reactions causing the burning. The riser acts to accomplish sufficient natural draft by concentrating the flames from syngas to increase the upward draft.
We started out our Week 6 weekends by dumpster diving around campus. We were able to collect cans of various sizes for future prototypes. Afterwards, we divided up into two groups to finish the construction of the apparatus. Adam and Wenxi configured three cans to be assembled easily for the apparatus. D’Arcy, Jessica, and Pauline learned how to use the drill press in the PRL to drill the appropriate holes into the three cans. Currently, we are working on obtaining a thermocouple and appropriate lighting material as well as screening the cacao husks to prepare for our burn in Week 9!
Beyond our design, we were able to connect with Brad, the chief chocolate maker at TCHO, for our second partner call. During our call, we shared our slide deck with him (derived from our midpoint presentation). Brad is currently traveling to Ghana and is excited to share our slide deck with his contacts at CRIG so that we can begin a partnership with CRIG. Considering ethical community involvement, we are hopeful that after Brad’s trip, we will be able to establish connections with CRIG and receive input from the groups of people we hope to potentially benefit with our biochar apparatus. Being mindful of these considerations, our group had a lot of discussions with our hesitations about moving forward with this project without having had much conversation with potential stakeholders that we have not yet established connections with. Finally, towards the end of Week 8, our group worked on outlining an O&M manual to enumerate system description, routine operation and maintenance procedures, emergency response plan, laws and regulation, commissioning and testing results, training, and relevant resources. We hope that by having an O&M manual, our future community partners will have the tools to be able to sustainably operate and maintain the relevant infrastructure.
After a half a quarter of planning and research, the TCHO team is finally starting to put together our design! The past few weeks, we have developed our project and methodology, and have come up with potential designs and design alternatives. Initially, our main apparatus focused on a single compartment TLUD the size of a paint can. Upon further research, however, we preferred the pressurization from a dual component TLUD. The main drawback of the latter is that we would have to weld—a skill the majority of the team is not yet comfortable with. Moreover, for either of these options, we would need to limit emissions from the can itself, and since we are using old food cans of variable, and often times unknown, composition, this posits a significant concern for the team; these old cans may also not be able to withstand the high temperatures and pressures we hope to achieve.
Beyond a design, last week we presented the pitch for our project, enumerated a week by week plan (Gantt chart), and identified risks. Most realistically, we are concerned with the development and construction of our project—namely the risk of going over budget or not finding materials. Furthermore, we have finally scheduled our second partner call with Brad, the chief chocolate maker at TCHO. Scheduling has been difficult, nonetheless, after many failed email attempts and missed connections; but we are hopeful that Brad will put us in contact with CRIG and community partners in Ghana. Considering the many conversations we’ve had in class about ethical community involvement, we are hesitant to move forward in our project without input from the groups of people we hope to potentially benefit.
The TCHO Team is off to an exciting start with clear goals and objectives for the coming quarter. To begin, our team started with a comprehensive lit review to examine the current methods of biochar production both locally and internationally as well as the benefits and prospects to biochar use in Ghana. Our review pointed us towards the use of Top Lit Up Draft pyrolysis for small scale biochar production. We have looked at a variety of apparatus designs for rural areas with limited access to resources in Thailand and Nepal. Designs ranged from construction in oil drums to paint cans and corrugated sheetings. As we continue to work on our design assessment, we are considering the objective and scale of our design, and what priorities are most salient for our first year of experimentation.
Additionally, we had our first partner call with Brad, Chief Chocolate Maker at TCHO. We were able to get a team briefing on more contacts that we could get into contact with in Ghana and at CRIG (Cocoa Research Institute of Ghana). Further, we learned more about the fermentation process and the size and scale at which the husks are discarded. Brad talked to us more about the nature of the farms in Ghana and his knowledge of the pertinence of the project to the area. We were able to learn more about farming practices, current disposal methods for the waste stream, and the approximate size of these farms. Brad also talked to us about getting access to husks here at Stanford.
On Sunday, TCHO hosted a party after the Fancy Food Convention in San Francisco, and had pods on display at this event. Brad invited us to the party and told us we could pick up the pods there afterwards if this was convenient for us. Latifah, D'Arcy, and Adam attended the party and were able to meet with Brad and other business partners at TCHO, then retrieve the pods (and plenty of free chocolate) to bring back to campus. While it was initially researched that the cacao husk composed about 90% of the mass of the pod, after preliminary analysis of the pods received, this number looks closer to 70%. This is still a significant portion of the pod, but it important to note the significant difference from sources found online. This week, the team will be focusing on developing three fleshed out designs for a TLUD pyrolysis apparatus and begin practicing welding in the PRL.