The Biochar team has been making progress on our first functional prototype of this year's kiln! Upon arrival of the 5 gallon metal bucket, lid, and aluminum duct tape, our team got to work in the Product Realization Lab (PRL)—a makerspace at Stanford—with the help of our project coach, Marshall Hartung. In all honesty, our first day in the lab was not as productive as we had hoped it would be. We ran into a lot of issues when deciding how we would approach the air holes at the base of the bucket. We were specifically unsure on how we could evenly distribute the quantity of holes across the circular base. It took a lot of mathematical trial and error, but after measuring the diameter of the bucket to be around 10.5 inches, we ultimately decided to implement the holes in a set of 4 concentric circles using a polar coordinate system. The radius of each circle increases by 1.05 inches as we spread further out from the center of the base, and there is a 1.05 inch buffer from the base’s circumference to the largest circle. From innermost to outermost, the circles are composed of 5, 10, 14, and 19 air holes, and the very center of the base has an additional hole. The increasing number of holes in each concentric circle corresponds to the increasing circumference of each to result in an even distribution of holes—which we hypothesize will provide a relatively consistent primary airflow across the entire base of the kiln. In total, this sums to 50 primary air holes, a number we determined based on literature reviews from previous years’ prototypes. For the secondary air holes, we chose to mark 12 holes evenly spaced out around the kiln’s circumference, all around 1 inch from the top of the kiln. This figure was from the 4:1 ratio of primary:secondary air holes that the literature and tutorials we found on metal TLUD kilns suggested. Once we finished calculating and marking the exact location of each hole on our kiln, we got to drilling (pictured below 📸)! We started with a 0.25 inch drill bit, and will conduct our first set of tests with holes of this size. As part of one of our desired experiments, we will gradually use larger drill bits for larger hole sizes (and more airflow) in the future. We’ve also begun cutting into our kiln lid (6 even triangles that will fold upwards to hold the chimney on top) using a Dremel and will finish the cutting process early next week in the lab. After the cuts are made, we will fold the resulting flaps upwards, slide on the chimney (consisting of two metal tin cans taped together using aluminum duct tape), and have our finished prototype! As far as next steps go, we’ve put together and submitted our proposal to use the Stanford Educational Farm (a diagram of our proposed plans is pictured below 📸). Once we hear back from them, and have sourced maize cobs (either from the Farm or from another source), we will begin the tests mentioned in our first blog post using a method similar to below. In the meantime, we’ll be finding (or purchasing) all the measuring tools and resources we need, such as an IR thermometer, air quality sensor, biochar quality testing kit, and lab space. And finally, we'll meet with our community partners next week to try and connect with local metalsmiths and community members in order to gauge the accessibility of our current kiln design.
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Welcome to our blog! 👋 We're The Kilners, a group of four chemical engineers at Stanford tackling an ESW project during Winter & Spring 2024. From left to right in the picture below 📸, we're Alison Fajardo ('26), Nifemi Ibrahim ('27), Danna Soriano ('26), and Kunal Arora ('26, team lead). Before we dig into our plans for the quarter, here's a brief overview of our project goal and community partners. The Biochar project aims to create a sustainable and accessible cooking device for rural communities of Malawi. This kiln, made with locally-sourced items such as buckets and cans, provides an affordable way for members of the Malawian communities to produce biochar, a charcoal-like substance which has many potential benefits (e.g. soil amendment) to them. Additionally, by using biomass (i.e. corn husks and rice husks) to fuel the kiln, community members will contribute to a decrease in agricultural waste and deforestation (widely practiced in Malawi to source wood for fuel). Finally, the kiln, in the process of producing biochar, lets off heat that can be used to cook; our team’s goal is to ensure the cooking process is smokeless to reduce the problem of indoor pollution in Malawi and its associated health effects. We have two community partners: the Wildlife and Environmental Society of Malawi (WESM) and Mzuzu University. Since Biochar is a returning project, these partners have helped our team historically and we have an established relationship with them. WESM’s mission is to conserve the biodiversity of the country, and hence their investment in the project is in its potential to decrease deforestation. They also work directly with local communities, and thus bring insights into the perspective of the users we hope to reach. Mzuzu University, as a research institution, is especially interested in the global health benefits that this project can bring to Malawi. Their scientific expertise, lab spaces, and wealth of knowledge are invaluable to the project. So where are we now? Last quarter, we explored several designs and created a final prototype (pictured below 📸), which will be our starting point moving forward. Our plan for spring is to begin our metal prototype. We’re at the end of Week 1, and have placed an order for a 5 gallon metal bucket, lid, and aluminum duct tape. By the end of next week, we want to get more comfortable with using Product Realization Lab (PRL) tools and finish building our testable prototype. When it comes time to test, we’ll connect with the Educational Farm on campus to source maize cobs and find a safe place to carry out our procedures. We plan on running 3 experiments. And for each experiment, we’ll plan on measuring the duration of the burn, temperature of the burn, biochar yield, and quality of biochar (via density and porosity of the product, which we hope to measure using Stanford research labs).
~ The Kilners |
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