Sunday, April 8, 2012

How Fluffy Animals Make Everything Better

This semester, Saturday is Manure-Shoveling Day.

Let me explain: one of my majors is a combined degree in interdisciplinary engineering and management.  In your last semester, you take a rather ambiguously-defined course in which you're supposed to work, in a team, on a senior design project. When that semester rolls around, your adviser sends you a list of projects, you pick your preferences, and after all the responses are in, you get sorted into a project.

I'm working, along with a team of other people, on a small-scale anaerobic digester project.  In theory, it's a really neat project-- you put all your organic waste in a big tank, the anaerobic bacteria work some bio-magic, and hey presto, out comes liquid fertilizer, solid fertilizer, and methane, which you can use to generate heat/electricity.  The process is also supposed to deodorize the organic material, so if you spread it on your garden, the neighbors won't complain.

In practice, we have an experimental digester, and the process is less magical and more smelly. Surprisingly (to me), collecting the manure from the cow enclosure is actually kind of nice.  The cows at the farm are pretty relaxed-- they come over to you to say "hi" before wandering off to do their cow business, and I'd never before realized how sweet hay can smell over manure.

The miserable part comes once you get out of the cow enclosure.  The wheelbarrow gets stuck on ridges or in the soft ground on the way to the digester.  Once you've either carefully avoided or muscled over the obstacles, you arrive at the real obstacle: the digester itself.  It lives in a little shed.

Somewhere during the design process, the person designing the manure delivery system assumed that manure behaves mostly like potatoes. The person designing the digester tank, on the other hand, assumed that manure behaves mostly like water.  In reality, manure behaves mostly like sticky goop of varying consistencies with bits of hay stuck in it.  In short, the digester doesn't quite work for any consistency of manure slurry-- the hay clogs the manure input, the manure conveyor doesn't convey the manure to the input slot six feet above the ground, and the heater that keeps the manure the right temperature for digestion doesn't heat the tank evenly because the manure doesn't circulate like a liquid.

In order to keep the digester working so that we can get some data out of it, we have a number of workarounds for all this.  We have to avoid hay clumps or pick the hay out of the manure with the shovel. We have to pitch the manure up to the tiny six-foot-high opening, and then when it inevitably sticks to the side, we have to stand on a bucket and use a stick to actually prod it into the tank.  We have to mix the digester for fifteen minutes every hour in order to keep the temperature high enough.  In other words, the feeding process involves several manual steps that should be automatic. In addition to this, the digester shed reeks, and the smell stays with your clothing until you've washed it. Twice.

I do the whole routine once a week, and after I get out, I'm usually splattered with manure and a bit grouchy until I get home and shower.

Yesterday was a bit different.  I had a visitor.


This fluffy white kitty came over to the area in front of the digester where I was pitching manure.


It rolled in the dirt and walked around me as I waited for the digester to complete its mixing cycle.  It didn't seem to mind my manure-encrusted clothes or my habit of talking to the machines I work with, as it stayed in the area the entire time I was working.

I left the farm with a smile on my face.

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