Complete Biogas: Food Waste and Biogas, Part 1

Reader Contribution by David William House
article image

There’s a gold mine out back of your local restaurant.

…Or at least that’s one way of looking at it. Of course, what I’m talking about is wasted food — the stuff you don’t eat from your plastic tray of super-sized this and that, the French fries that got a little too brown in the fryer, the stale burger buns. That stuff. It’s gold, really.

As my good friend Bob Hamburg of Dragon Husbandry once said:

“As for ‘waste disposal,’ we’ve got two mis-defined terms mashed together, resulting in an abominable oxymoron. In nature there is no such thing as waste. All residues serve as resources for further growth — there is nothing to be disposed of. Nothing is thrown away. Indeed, there is no ‘away.’ Everything must go somewhere. The misconception of ‘waste disposal’ must be superseded by a better understanding of ‘residue management.’”

Right on, Bob.

But hey, look at the stuff in that trash bin: It’s gooey. It’s gross, right? Who really wants that stuff, anyway? Well, maybe you will, when you see the whole picture.

Waking Up to Nature’s ‘Waste’ Management

It all grows out of standard ecology, the way the planet deals with energy and information (and the way we will, too, once our species gets past adolescence). Sunlight enters the atmosphere and makes green things grow: The largest usable bank account of stored solar energy on the whole planet is the set of green growing things, all the way from algae to giant sequoia. And a small fraction of that green riot is harvested to feed us and our animals.

Now in our (present, soon to be superceded; have faith) way of doing it, plant resources all go into factory-type buildings and come out as packages. Then, the packages are opened, we prepare food and eat it, and all that packaging trash is thrown away along with the food we don’t eat: more wasted food. We send it all to landfills or incinerators, go to sleep, wake up (sort of) and do it all again.

In nature’s way of doing it, just like Bob said, there is no “waste.” Ecological scientists talk about “trophic levels,” which in part is a way of saying that whatever one living thing leaves behind, another living thing uses as a source of energy. Plants consume sunlight, air and soil to produce green matter to feed vegetarians, such as cows or caterpillars. Vegetarians consume green matter to produce flesh to feed carnivores, such as wolves or people (or birds that eat caterpillars). And when anything once alive dies, then (if there is enough moisture available) the remains feed arthropods (little bugs), fungi, and a seething mass of microscopic life: nature’s compost pile.

This is the picture of the energy of life being shared among all living things, in a kind of sacred dance, happening all around us and unseen by most. The threads of the complex web of life are each connected to each — except where they are broken by the ignorant actions of man.

Stored Solar Energy

But hey. Too serious, right? Sure. But even still, that’s what we should maybe see when we look at that food behind the restaurant. Gooey? Well, that’s one way of seeing what’s there.

Yet maybe one of the wisest ways of seeing what’s there is to think about all that energy tied up in the carbon bonds of that food: the stored solar energy that can help you cook your own food, make great compost for your garden, and even heat your house, if you have enough of it.

How can this energy be put to use? Well that’s a story for part two.

Photo: Matt Steiman’s hand (Matt is Assistant Manager, Dickinson College Farm and Project Support, Dickinson College Biodiesel) pointing out a feature of the 3-year old EDPM plug-flow digester inside a greenhouse at the Dickinson College Organic Farm. Matt says: “We are making plenty of gas for cooking at the intern kitchen…. Currently we transfer gas from storage near the biogas digester to our kitchen using inner tubes that we fill from a manifold attached to our gas measuring drum. The 100-liter tubes are weighted at the kitchen and provide enough gas to cook a meal or two on our single Chinese burner.”