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Make Homemade Biogas Energy, Not Food Waste, at the ‘Complete Biogas’ Workshop

Scraping Food From Plate

Photo by Flickr/jbloom

Some years ago, my wife took a public speaking class. Occasionally, she was supposed to give a speech of her own devising, but like many famous and busy people, she decided to hire a speechwriter. After an extensive international search, I got the job.

One of my favorite speeches that she gave— superbly written, as I recall — was about sugar being the root of all evil. After all, wasn’t sugar responsible for the “triangular” slave trade? In an era without tractors, where else could they get cheap labor? And wasn’t it sugar, made into rum, which caused so much misery? (Some would say rum caused a lot of happiness, too, but hey, we’re trying to prove that sugar is the root of all evil here, so keep your eye on the ball.)

Then there’s sugar and tooth decay, sugar and skull malformations (you could look it up: search for Weston Price), and it is well known that sugar encourages both sloth and licentiousness. (I just made that last part up.)

I’ve decided, though, that food waste sent to landfills runs a close second as the root of all evil. There are a few good reasons to think so.

Food Waste, Hunger, and Climate Change

You might know that worldwide, something like a third or more of the food grown is never eaten: It simply goes to waste. In the U.S., some estimate that 40% of our food is thrown away — and the true figure may be higher than that. It amounts to better than 1,200 calories per person per day in the U.S. In a world where children go hungry, should that happen? In a country where some report that one in six are hungry, should that happen?

All that’s bad, but it gets worse. Much of this food waste is taken to landfills and buried. Nearby oxygen is quickly used up by bacterial life, so the food waste goes anaerobic. It produces biogas, which is almost entirely carbon dioxide and methane, and when that methane escapes into the atmosphere — well, if you were paying attention in science class, you know that methane is a powerful greenhouse gas, contributing to manmade global climate change. Some people say that it is 25 times worse than carbon dioxide, but newer research has demonstrated that, pound for pound, methane produces something between 70 and 100 times the impact of carbon dioxide.

For such reasons, the Food and Agriculture Organization of the United Nations (FAO) says that if the greenhouse impact of food waste were ranked as if it were the output of one of the world’s  nations, it would be third, after the U.S. and China. That is, the impact of global food waste on climate change is greater than the GHG emissions of the entire sub-continent of India, all sectors included.

Further, according to the Environmental Defense Fund (EDF), the production of methane accounts for “about 25% of the manmade global warming.” Finally, the chief scientist of the EDF has said that “by emitting just a little bit of methane, mankind is greatly accelerating the rate of climatic change.”

“Wild” methane turns out to be a big problem, and food waste is an important contributor.

What Can Be Done?

Now, everyone has their own work, to be sure. Some of us will be raising babies to be wonderful human beings; some of us have nine to fives, five out of seven; some of us write speeches. Some have more freedom to choose, some less. Some look up, and some keep their heads down. It takes all kinds, right?

And as well, some of us want to do something about one or more of these Big Problems. We’re pretty sure that life is a wonderful privilege, and therefore, it necessarily comes with important responsibilities. It’s not that we can solve any of these Big Problems all by ourselves. Rather (we think), it’s that everyone has to find their own spot and then stand there and make it a little better.

So, this methane/food waste thing one of these Big Problems. And yet, this methane/food waste thing is, at the same time, a great opportunity. When the methane is produced “in the wild”, it has a dramatic, short-term negative impact on climate change.

But when we deliberately generate biogas from that same would-otherwise-have-been-thrown-away food waste, we gain the lovely, nearly invisible blue-flame energy. We also produce a great fertilizer (the leftover effluent) and the combustion byproducts are carbon dioxide and water, replacing the “wild” methane and reducing the GHG impact to something between 1 and 3 percent of what it otherwise would have been. We have tamed the beast!

Making Biogas Make Sense

The good news is that biogas is easy to make. It’s the only biologically based renewable energy, besides combustion — simple fire — that happens and then persists in nature. (That’s not true of alcohol, not true of biodiesel.) But if you think about it, you already know that, right? ‘Cause we said: Toss food waste into a hole and cover it up, it will generate biogas/methane. So, it can’t be that hard, eh?

Well, yes and no. Yes, it’s blood simple in nature — it happens all by itself. But also no, the biogas biology can be fragile and finicky, although there are ways to make it more stable, if you know what you’re doing.

But the biggest difficulty is that the biogas biology very much prefers to be toasty warm, and the rate of biogas production depends on the internal temperature of the digester. (This spreadsheet will give you some numbers.)

I can’t tell the whole story here and now, but the take-home is that you need an insulated, heated digester where the contents can be stirred or agitated. Otherwise, if the contents of the digester are “at ambient” —  outside air temps — then, even in lovely Florida during the winter months, an unheated digester will stop producing biogas.

Now, if this were still 2016, that would be pretty much the end of the story. 1) Here’s a problem. 2) Here’s a potential solution, but, oops, sorry, 3) you will have to figure out how to make a digester, because there was no low-cost, small-scale, DIY biogas digester widely available which was insulated and heatable.

Learn to Build Your Own Biogas Digester in This Workshop

Homemade Biogas Digester Exploded

[The_Cube] home-scale biogas digester.

 Well, now it seems there is. This new wunderkind is called [The_Cube]. You can read a lot more about it here, if you’d like.

I’ll be writing a lot more about all aspects of this new digester, using this blog to tell you when plans are ready and other Pretty Neat Stuff, so keep coming back to MOTHER’s site for more juicy details. As well, you may want to sign up for email notifications and further information, here.

Meanwhile, we will be teaching workshops — including a Complete Biogas Workshop May 4-8, 2017, in Aurora, Oregon —so that anyone who wants to find out how to build these digesters from parts you can get at your local hardware store: polystyrene insulation (the pink stuff, rigid boards), various bits of lumber, some pipe and such, a small resistance heater, a fountain pump, and a few other items. The first day will be “all about biogas”, and thereafter, we will spend time building one of these digesters, and experiencing some hands-on manufacturing techniques. More details in the link just above.

We won’t be holding anything back, mind you. Come to a “builder’s” workshop and you will learn everything you need to know about how to produce complete digesters from locally purchased materials: as many as you want.

As well, this auspicious year of 2017, one of our main goals will be to work hard to put together everything we need to enable folks to use these digesters (and upcoming designs) to make a business out of saving the planet, one soggy French fry at a time. Further, we will be releasing plans, for those who cannot (yet) attend a workshop, and likewise selling kits. Stay tuned.

In sum, that’s the 411: Food waste, bad. Methane, worse. Biogas, good. You can make it, burn it, gain energy (and high quality fertilizer!), using [The_Cube] and follow-on designs, and you will then be responsible for withdrawing food waste from the landfill and thus doing a very good thing.

You can be a global warming warrior. You can become personally carbon negative!

Homemade Biogas Digester Plan

David William House is the founder of Earthmind, an educational nonprofit that teaches about ecological living, as well as Computer Classroom, ici (computer sales), and an eponymous computer consultancy. He’s the author of Methane Systems, The Complete Biogas Handbook, Journey (a book of poetry), and numerous articles. David is also the designer of a low-cost, plastic-bag-based biogas digester for equatorial belt countries and inventor of a patented new technology for cochlear implants. Find him at The Complete Biogas Handbook and read all of his MOTHER EARTH NEWS posts here.


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