The Anaerobic Biodigester: Simple Technologies that Make a Big Difference

When I was about 13 years old, I decided to enter the local science fair. This was my third time in the competition and I enjoyed doing it each year not because I wanted the extra credit at school or because I particularly enjoyed the significant amount of extra work, but because it was always a great, school-endorsed excuse for me to make a mess in my parent's basement without their disapproval. My first ever project was the construction of a mechanical waterwheel which I fashioned by taking a hack-saw to my sister's bike (sorry Carmen). The second project had me making epoxy glue derivatives and testing their strength by hanging hundreds of pounds of dead weight on them until they crashed down onto the concrete floor (sorry Dad). There was also that famous epoxy mixture I created that ended up melting the cup and part of the table I had mixed it in (sorry again).

But that year, at age 13, I decided I wanted to try something different. I can't recall exactly what I was thinking at the time, but in retrospect it must have been something along the lines of “How can I fill the basement with animal manure and light things on fire without getting punished?” The answer was a biodigester, basically a fancy contraption that captured methane gas produced by decomposing animal feces which could then be burned for fuel. The project was a success thanks to my wonderful mother who went above and beyond the call of motherly duties by collecting the necessary stock (animal manure) from a local horse farm (sorry Mom). In the end, this project earned me first prize at the local science competition and would stink up our basement without disciplinary recourse for well over four months. It was decommissioned at my family's unanimous request sometime after New Year's day.

Flash forward to 2013. I am now 24 years old and serving as a Peace Corps volunteer in the country of Paraguay, still just as curious and troublesome, but now with a license from the US government to do so overseas. My position as an agricultural extension volunteer in a poor, isolated rural community had me working a lot with small-scale organic systems at the familial level. I had worked extensively with composting projects and bio-intensive gardening to help improve household production, nutrition and sustainability. All of this work was rewarding but I felt as if there was something more I could do, some next step that I might be able to take with my community members that might give them a better appreciation of the depth of potential contained within their small parcels of land.

One of the initiatives of the Peace Corps Paraguay agricultural sector is sustainable permaculture systems, which essentially means taking advantage of the energy available at all points of agricultural production. Included in this initiative was a great project called the anaerobic biodigester, an green technology used for generations by farmers in India and China, but nonetheless effective, simple and novel to my community. This small-scale biodigester was really just a mock-up version of almost the same project I had done when I was 13, except now it could be put to use helping impoverished farmers provide for their families instead of just stinking up my parent's basement.

The design we used was developed in part by my boss, Fernando Gonzalez, who has been using a biodigester on his family's farm in Paraguay for over a decade. With his guidance and experience, I began the long process of applying for a micro-finance loan to help fund the project in my community. While the biodigester can be built with local materials and is relatively inexpensive (about $125 a piece), such up-font costs are still quite out of reach to the people I live and work with. After receiving the money, we held educational sessions with 15 adult members of my community where we described the project and the theory and walked them through the simple steps to construct one at home. In the end, we successfully installed two separate biodigester systems with two different families in my community.

At first, the biodigester might seem a stinky and cumbersome way to produce bio-gas for fuel purposes but the impacts of such a simple concept for small-scale farmers can be enormous. In a country such as the US, with an abundance of cheap fossil fuels (natural gas, petroleum, coal, etc.) most of us wouldn't waste the time handling animal manure if we could help it, however, in parts of the world where manure is much more abundant and accessible than disposable income, the biodigester can make a great difference.

The biodigester serves to produce bio-gas, a methane/hydrocarbon/water-vapor mixture that can be burned to cook food or heat a home. This fuel source means that families do not need to use up valuable financial capital to buy propane gas or be forced to slowly deforest their small properties to cook over wooden stoves. Additionally, and just as importantly, the biodigester produces a super-charged organic fertilizer that helps to boost garden production. The fertilizer itself is actually so strong that it can be diluted one part to twenty with water and still be extremely effective. Other secondary benefits include human and animal disease reduction and cleaner water supplies, a by-product of proper management of animal wastes.

The first time we lit-up the bio-gas stove with my neighbor, he threw down his hat, put up his arms and started jumping up and down with joy. He looked at me and said, “Mario, this whole time, I didn't believe you when you said it would work. Now I believe you, you crazy American.” Within a month, in addition to the bio-gas, these families have also noted a substantial boost in household garden productivity thanks to the biodigester's fertilizer component.

I can already tell that this project did as much for this family's sense of pride and motivation as it did for their material disposition. No doubt, it has helped them in a number of tangible ways, but more than that, it has given them something else to be proud of, it has planted a seed of inspiration in their minds. For people who have been farming and subsisting the same way for generations, the simple idea of the biodigester has opened their eyes to future possibilities that had never before been considered.

In developed countries, it might seem silly to think about what proper animal waste management and simple technologies can do for us. We drive our own cars and plug into our iPhones and never give a second thought to the fact that we are living in a universe of energy and potential and yet, have only really figured out how to master one of those sources (and a finite, pollution-ridden source at that). Something like the biodigester might seem a good solution for a poor rural farmer in some far-flung corner of the globe, but the reality is that we are facing a lot of the same problems right here at home. Climate change, pollution, deforestation, crop-failure—these things are not strangers to the developed nations and as the world spins onward into this next millennium, they will only become more familiar.

I am not saying that every family should go out right now and start building anaerobic composting systems in their backyards, but we need to start thinking more seriously about how we are going to provide for our energy needs and the needs of our natural world in the future. Yet, we shouldn't look at this as some sort of doomsday scenario, but instead an amazing opportunity. 

As a kid, such alternative energy possibilities fascinated and intrigued me. A decade later, they have done the same thing in an isolated, rural Paraguayan community. Maybe the next step will be to bring it full circle, to bring it once again a little closer to home. One small step at a time. But at least this last step got me out of my parent's basement and into the open air.Thanks for the help you guys, sorry for all the stink over the years.