Complete Biogas: Designing a Low Cost, DIY Biogas Digester for North America, Part 2

Reader Contribution by David William House
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When last we left you, I was talking about my friend from Sri Lanka, and the prospect of helping the poor in that country— and worldwide— through low-cost biogas. (And my apologies for the radio silence: I’ve been busy…)

Ideals are important, to be sure. And some say that we are either idealistic or realistic, as if becoming aware of injustice somehow necessarily prevents us from addressing it. But at least in my experience, that’s just not the way the world works. Just look around: there are a fair number of people who are both idealistic and realistic: but we could always use many more.

No doubt talk is cheap, and many things are difficult. That means that whether our goals are noble or selfish, failure to achieve those goals is not uncommon. But hey: Surely it’s better to fail when trying to help people escape poverty than it is to fail to add another zero to our personal wealth, no? (The zero is supposed to go on the right-hand end of the number, for any who were unsure…)

My father taught me a lot about how to find ways to have high ideals and achieve goals. (He invented the cochlear implant, if anyone can be said to have done so. Dr. William House: you could look it up.) And after all, I reasoned (underneath my gray hair), I’ve done my service to capitalism, established a strong marriage, raised a family and launched them into their amazing success stories (and they are amazing; just ask me)… So what was preventing me from trying for this brass ring— helping the poor worldwide— except a desire to sleep late on Sunday?

Well naturally then when my friend from Sri Lanka woke me up to the potentials of biogas for global benefit, I began to pursue this dream of helping many, many others, with limited resources and all by myself. How does one do that in a practical, step-by-step, realistic manner?

Well, you won’t be surprised if I tell you that thus far, it’s fair to say that what I’ve tried has met with limited apparent success. I won’t bore you with all the messy details, but let me give you a sketch.

I first tried a very conventional approach, developing a darn spiffy, multi-page, gee-whiz spreadsheet, a timeline and other accoutrements, and using these to pursue grants. But after shopping it around and doing the standard hey-there-fund-this-grant two-step, I was left with the feeling that I was standing on a field— along with 10,000 other folks— where all of us were waving our particular fistful of paper about our particular Good Idea, trying to gain some funding, then maybe some attention. Up close maybe you could hear one of us. From a few yards further away, where I imagined the closest grantors were standing, it would have been just sort of a lot of noise.

The experiences left me with the thought that, well, this would be a lot easier if I was able to get the attention first; the funding will follow. So I began to plan and build a solar-heated greenhouse with some fairly revolutionary features, intended to house a 10-cubic-meter digester fed entirely with food waste from a local restaurant. I got some modest funding from a few good friends, developed the design, spent months going up and down a ladder, and gradually the thing began to take shape. Here was to be something that people could point cameras at, to come and watch biogas in action.

Then, months into the build, a huge winter storm came through and brought it all down. Wham. Flat. Kindling. I had neither the heart nor the funds to start such a large project again…

Meanwhile, I had developed a small, very cheap digester suited to the tropics and intended to be manufactured in quantity. Materials cost? $10.

Now, I happen to know something about design and manufacturing because of my past work experience, and I knew that for something like a digester-for-the-poor— which is supposed to work well where every floor is a dirt floor— one crucial design process is to have people bang on the thing and try to break it. It should be reasonably sturdy, right?

So to provide funding for efforts to improve the design, to get the designs out and about and under stress, and to begin the process of gaining attention, I decided to start teaching workshops about biogas, capped with a half-day segment where we would all manufacture these low-cost digesters from kits and parts.

That went very well. I love to gab and I had something useful to say. My dear friends Tim and Suzanne of Friendly Aquaponics invited me to come to Hawaii and teach, I got invited to Australia, and the National Center for Appropriate Technology organized a workshop in Iowa, just to mention a few. From California to upstate New York, groups of charged-up folks had a good time and learned all about biogas. And they loved it, at least according to the evaluation forms I gathered from each class.

The favorite part of these workshops for most of the participants, it seemed, was building those low-cost tropical digesters. But at the same time, that was also the key problem, that little word there: “tropical”. The information was good, the folks were enthusiastic, the workshop was humming and the digesters were… tropical. In Iowa there was snow on the ground. In New York, it was early spring. Too cold. Even in Hawaii, perhaps surprisingly: it was too cold almost everywhere.

Then this last spring I was invited to do a workshop in Brooklyn, and as I was doing the work to prepare for it, I gradually came to realize two things. The first was that these workshops, as popular and fun as they were, were not going to get me close enough to the brass ring. It was a great job description to add to a number of others, like “scriptwriter” that I had accumulated— “Biogas workshop leader”— but all by themselves, these get-togethers probably weren’t going to get me to Sri Lanka, organizing the manufacture and distribution of many thousands of digesters.

It hit me: I had given a lot of thought to low-cost, practical, tropical digesters, but I hadn’t thought at all about digesters that would work in Burbank, upstate New York, or Iowa in the winter during a hard freeze: That is, almost anywhere on this continental land mass here that I’m sitting on just now.

The good news, as I came gradually to realize, was that all the design ideas and testing, all the invention of manufacturing equipment that I had undertaken in my quest for tropical, could help me— it could help you, come to think of it— to produce that utterly rare creature: A low-cost, well-designed, small biogas digester that will work profitably here, where tropical is a travel brochure, not a weather pattern.

The key ideas, as it turned out, were pretty simple. What I knew was that if I took two sheets of plastic and carefully pressed them— compressed them— together along a line, say with a couple of 2-by-4s and a bit of weather-stripping, nothing would leak through that line: not liquid, and not gas (at least not at low pressures). So in fact, with a bit of ingenuity and modest folding, I could create a water- and gas-tight container out of plastic sheets pressed into place by rigid pink polystyrene foam insulating boards, held in place by plywood. The polysty would provide good insulation. I knew from my experiments how to create a very cheap, very strong bung— a pipe-hole through the wall— and that’s all anyone really needs: A tight box with some pipes, minimum three: a slurry inlet, an effluent outlet, and a gas collection pipe.

And that’s it right there, really. That’s an entirely new design for a biogas digester which is cheap and well-insulated: the grail. And for the next many posts in this blog, that’s what I’m going to tell you, in some detail, how to make.

It will take more than a few posts and therefore some time, because there’s only so much you can say in a 1,000 words or so, even with pictures to multiply the syllable count. If you want to learn much more, a lot more quickly, then you are welcome to attend the next Beginner’s Biogas Workshop, which will be held in Washington DC in mid-April. (Read the details.) There and then, we will be revealing all. (Well, almost all. But in any case, enough.)

And if you can’t make it there, then no worries. There will be more workshops (sign up to be notified on the TCBH site), and whether or not it’s practical for you to attend a workshop, keep reading the blog and I’ll tell you everything I can.

Here’s my hope, finally. This isn’t just about providing practical, cheap, small biogas to a small set of dedicated crazies in the US. I firmly believe that this effort can help catalyze greater use of wasted food in this lovely, forgetful-of-its-high-ideals nation, and that in turn, it is my fond hope, can have a measurable impact on the release of climate changing ‘wild’ methane from out of landfills. (Food wasted around the world produces as much greenhouse gas as all the annual emissions of the entire country of India, the third largest GHG emittter! And if we can reduce methane emissions, according to the New Scientist magazine, we can delay the impacts of climate change by 15 years… Hey: that’s worth doing, right?)

Then finally, if I can create enough excitement and pay down my mortgage from these efforts, I’ll bet I can take it all the way to Sri Lanka. What do you think? What are my chances?

Keep reading, and we’ll both find out.

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