Open source design in Guatemala: Treadle Pump & solar fridge

A few months ago, I wrote about how AIDG is upgrading its R&D facilities in Guatemala. Woot. An extra benefit of this process is that we can collaborate with more groups who want to design for the BOP. Specifically, we can help them understand what additional material and other constraints they need to take into consideration during their design process. One of my favorite bloggers and head of the Appropriate Technology Collaborative, John Barrie, writes about 2 engineering student teams that came to AIDG-Guatemala recently.

Open source treadle pump
Open source treadle pump [Sustainable Design Update]

I don’t know how we managed to put together such an incredible set of projects. Much credit goes to the student teams that worked nearly around the clock when in Xela.

Ben Connor Barrie and Jeff Tenza ran the show from our end. Karen and I had work in Nicaragua for much of the time so Ben and Jeff were on their own with the student teams. Ben started working with the student design teams for a few months prior to the build so he was familiar with the technologies and the materials needed for success. He also speaks Spanish and has had two years teaching experience with Teach for America.

Just as we got to Guatemala Ben commented “God I’m glad I don’t have to drive in Guatemala” as our driver cut off a truck and then was cut off by a chicken bus in rush hour traffic. The very next day we borrowed the AIDG truck with Jose Ordoñez to shop for materials. As we headed for the truck Jose gave Ben the keys and said Ben was driving. About half the student team from U of M went along for the experience. We ended up with 6 meters of steel on the roof in rush hour traffic hitting a round about – Jose giving directions in Spanish and Ben cursing in at least three languages. We all made it back ok.

University of Michigan BLUELab Team at AIDG-Guatemala
University of Michigan BLUELab Team at AIDG-Guatemala

The BLUELab team has been working on an open source treadle pump design since the start of school 2008. They got as far as a prototype or proof of concept model in their workshop, drew up incredibly detailed and easy to read documents and arrived in Guatemala after a daylong delay due to weather in the US. They also had to cut their visit short by a day on the other end due to flight scheduling problems.

The BLUELab team made up for lost time by being very well organized. They formed working groups for each component of the assembly. The reality of building in the developing world was made clear early when certain types of plastic weren’t available, pipe sizes were different from standards in the US and steel parts were also different from standards we have in the shop back home. Much was redesigned on the fly.

BLUELab worked all day at the AIDG workshop (thank you very much!) and then reviewed the next day’s assignments over a late dinner every night. They were successful in proving their prototype works on the last day of the build, at the last hour, with their bags already packed and their shuttle waiting.

BLUELab posted their work on their website and within 3 days NGOs from Africa were already asking for copies of their drawings. We plan on posting the revised design on the ATC website at the end of the semester and BLUELab is considering returning to Guatemala to build the new design.

Guatemala is probably not the place where treadle pumps will make a good business sense, but it is a great place to learn what it is like to build with limited resources. The experience for the student team, working with people from Guatemala and living embedded in a new culture will change how they view their work.

The MSU Refrigerator project started as an idea “from out of the blue” when I was at XelaTeco one day in the middle of a hail storm. I figured if solar forces could freeze rain then they could be used to chill vaccines. Three years later we had a team of Engineers from Michigan State University in Xela working on a solar refrigerator.

The MSU team is a group of students working on their Capstone Design Project, a senior design course that brings together all they have learned in engineering school in one final big design. Working with Dr. Craig Somerton we hand selected a group of students with the right skill sets to create and build a solar refrigerator using only locally available materials.

The refrigerator uses activated charcoal (made from coconuts) and ethanol to cool or freeze an insulated box. The MSU team calculated the amounts of materials needed, the surface area required for solar input and the surface area needed to condense the ethanol from gas back into a liquid form. They prototyped their project in East Lansing, MI and then hit the road to Guatemala with drawings and specifications in hand.

The MSU team gathered some of their materials on bicycle but did use the AIDG truck to move some heavy steel parts. They had to settle for extra strong steel due to a lack of steel at the gauge they had specified in their design. At the end of the first day they took several parts of their project back to their hostel and continued to work in the street out front to keep the project on schedule.

On Thursday the design was complete and it chilled the cooler box to just above 1 degree Fahrenheit. They designed the refrigerator to run continuously without having to attend to it using a very clever arrangement of the solar collector, condenser and evaporator. Based on our work in Guatemala we have a new design idea that may reduce the price considerably if we can make our own activated charcoal and change several components of the design from copper to steel. We also found evidence of a source of methanol in Xela. If we switch the refrigerant from ethanol to methanol the cooler should reach about -10 degrees F using all the same components.

We (ATC) are now working with student teams from 7 schools with more schools asking to join the collaborative. We are, at the point, where we have to balance our commitments with our capacity to investigate, invent and create good designs that are in the range of student design teams. We can support multi-year projects with different faculty sponsors and different student teams.

We have a long list of potential design projects, some are very complicated and some are the simple technologies that can make a difference at low cost. ATC is starting two projects with Business students this year. We are creating business plans manufacture and sell some of our technologies based on local market conditions.

If anyone is interested in our designs, they are all going to be online at by the end of this semester.

I am going to upload some of the spring 2009 photos to my Flickr account.

-John Barrie
John Barrie

Related posts:
Tech Update: MSU Teams build solar fridge at AIDG-Guatemala
Low cost solar water heater for Guatemala: AIDG and UC Berkeley research team partner up
Universal LED Circuit Board Project
Video: EWB-SF: Prototyping low cost wind turbine at AIDG Guatemala