Biogas or Bust – Chapter 3 – Checking In On Uganda

By Ryan LuckieUncategorized
I’ve posted the below entry as my “latest final post” on my original Peace Corps Blog.  As that blog is now 5.5 years idle, I thought I’d duplicate it on my current blog.  I’ve included links to the original Biogas or Bust series as well.

Biogas or Bust – Chapter 1
Biogas or Bust – Chapter 2

Around 6 months to a year after leaving Uganda, in the fall of 2012, I received an email from the Purdue Engineers Without Borders Chapter.  They had adopted the Biogas Program which I had proposed and had done preliminary designs for in Uganda in the Summer and Fall of 2011.

I provided them my thoughts on the feasibility of the program, challenges, general info on the region of Uganda and we mostly left it at that.  I had a full time job, a beautiful soon to be fiancee, and would be heading to Saudi Arabia in just a few months.  There was little I could continue to contribute to their efforts.

I wouldn’t check in with Purdue EWB again until I was returning from Saudi Arabia in early 2015.  They had completed their initial visit and assessment and were in the churn of development.  No hard timeline was in place, but  things continued to inch forward.

A few weeks ago, the thought crossed my mind to check in with them again. Years have gone by, priorities have changed, and despite it being a very special time in my life, I rarely think about my time in the Peace Corps, but for some reason, that day at work, Peace Corps and Biogas was on my mind.

I navigated to the Purdue EWB website and was soon having a moment of peace, pride, and pure happiness at my desk.  They had built it.

The main tank was constructed using curved and grooved interlocking bricks.   Stabilized soil interlocking bricks are a favorite of Peace Corps Volunteers in Uganda.

 In construction trip one, they built the main tank, including placement of the loading and spent fuel outlet pipes into the tank.

They chose a plastic cap over the main tank, fulfilling what my initial study had recommended in using a floating cap instead of fixed cap.  Fixed cap designs, like the ones shown in the link, seemed to require a higher skill set to build and seemed to present greater possibility of structural failure and catastrophic injury.  But it wasn’t that clear cut, all the designs I had previously referenced for floating cap designs used a sheet metal floating cap, the metal cap provided counter weight and expandable storage as the tank filled with gas… however, my preliminary design seemed to indicate the floating cap required for a digester of the scale we wanted would be too heavy to install, 900 lbs by my calculations, and precise sheet metal work in villages also would not be easy.  I like the solution they came up with below…

Constructing the base for what appears to be the loading tank. 

Obviously later, the concrete has cured and they are ready to place the cap.
This chain net hangs over the digester and links with counterweights erected around the tank edges.

When the digester fills with gas it exerts a force equally around the sides, but also exerts a force on the surface and roof of the digester, lifting the digester up into the air, as it rises the tank’s volume increases and therefore the gas pressure decreases.   This is the digester at peak storage, with counter weights lifted by the gas.
My recent correspondence with BUSODA indicates that they are using the digester for cooking and lighting around site.  The ultimate goal of the project is to develop BUSODA’s capability to reproduce and implement the design without assistance.  The Peace Corps mission is not about assistance but about sustainable solutions and development.   I’m extremely excited and proud of Purdue EWB because they’ve created something very different than my research into BioGas included and appear to have done it all with materials that can be procured locally and in a manner that will require no heavy construction equipment.  In every way this appears to be a reproducible and sustainable solution.