Its been about a week since I picked up the 8 cu yards of mulch from the municipal yard with BART. The grabbing of the mulch was almost instinctual, but over the past week some planning has set in as I need to be more methodical if I am to run a true Proof of Concept, let alone produce several dozen cubic meters of highly combustible methane gas within 20 feet of my home. But first, lets catch up on the past week.
A few on lookers had expressed concern about the ability of pure pine tree waste to decompose. That made me pause for a day or two- would the acidity funk with the microbial mix? What about the resins? No worries though, the pile steadily warmed and within 5 days was roaring away with steam drifting off each morning. Took a temp reading today and it was well over 140 in many spots, and the entire center was over 135. Hmmm… 4000#’s of material at 135 degrees. Yep, that should be more than enough bTU’s for the project!
There are several really unique things that Jean Pain did in his methods, most of which I will try to capture. First – he used brush. At first glance, wood chips seem to be way to high in carbon. But I have seen mulch piles heat up on numerous occasions, but they don’t stay hot long once they burn through their nitrogen. Jean’s stayed over 100 degrees for 18 months! A careful watching of the You Tube vids and readings of his book show a key point – he used GREEN, leafy brush. Green brush has a ton of nitrogen and sugar rich sap, and the pile of pine I snagged was predominately green in color – i.e. lots of nitrogen.
Second, Jean soaked his piles for 2 days in a giant ditch. Here is the what I am convinced this does and why it is so vital in his technique: the wood chips literally saturate themselves with water over the course of the 2 days. This provides a store of water for the pile to keep the bacteria from getting thirsty for literally months on end, but does not force the pile anaerobic due to the large particle size of the chips; the bridging allows for enough air to circulate. The bacteria live on the edge of the chips, and as they consume the water, more is leached from the interior of the chips through capillary action. From what I can tell, when Mother Earth News did their expirements on his methods in 1980, they skipped this step. I believe that to have been a fatal flaw, and one I do not wish to make. But how the hell do you soak 200 cu feet of mulch? With giant plastic totes of course!
These totes are HUGE – about 54″ cubed- and they hold over 2 cu yards or 350 gallons. I bought 7 last year on a whim, and gave 2 to a friend in exchange for the use of his pole barn to store them in and a clearwater 300gph pump from harbor freight for my Appleseed BD Processor. I love my life. Anyhow, I figured that 3 of these would be about perfect to fill with chips and water and let them sit for a few days to soak up all the goodness while I do some other projects like planting the 500 sweet potato slips that showed up last week. It took about 3 hours for my “intern” Kevin and I to get them from storage, drag them to the backyard, and fill them up. I also filled 3 of the 55 gallon drums I also bought last year for the biodeisel project. 2 of them will be the batch digesters, but I am getting ahead of my self.
Luckily before we began to fill them I had an epiphany as to how to drain them. Tipping on of these bad boys will NOT be an option once they are full of water, and even drained I think we will need some fancy levers and my 3 ton jack. My solution? I put the garden hose all the way to the bottom of the tote and filled them up as we schlepped mulch in. Once the water reached the rim, I unscrewed the hose from the house and hung the female end over a bend in the gutter about 7′ up. This preserves the water in the hose and will allow me to siphon out the water on Friday. If it works, it will be brilliant!
Next steps will be leveling the 100 odd sq ft needed for the Jean Pain mini digester compost pile. My plans there are to wall in the entire pile with 2-3 tiers of straw bales with the two drums in the center of a 9 x 12 rectangle. The straw will provide a (relatively) unobtrusive structure for the neighbors and, once staked, enough support to contain the pile. Also, I am hoping that the extra insulation will be an added benefit. Still sourcing hose to wrap the drums with to regulate their temperature, and I have another friend looking into pumps. After than I will need to rig up the drum lids with some barb fittings and hoses to pull off the methane gas. And then finally, the big unknown is the methane storage. Several options in the hopper- Jean used tire inner tubes, but not sure how OSHA would view that. Kids play in my backyard… Safety is a BIG concern.
Should have a post up later this week showing the completed pile, and will likely fill the drums either Friday or next week. Also, this thing needs a better name than the “Jean Pain Compost Methane Batch Digester Proof of Concept”.
I’ve always liked alliteration…
Enter the “Methane Midden”