Midden L’eau Chaude: The Big Build

Load #2 being dumped for a total of about 17 cu yards (13 cu m). Let's do this.

Last summer I built the Methane Midden which was inspired by Jean Pain’s epic work in 1970 France.    It was big, it was a little insane, and ultimately it didn’t work. Don’t get me wrong – it made a syck amount of compost, but it failed to meet my goals of also producing methane and hot water.  Time to do better.  The second Midden will focus on Hot Water (L’eau Chaude) with a dedicated heat exchanger and will be even larger.  Not only that, but I wanted to learn how much material it truly takes to make one of these so I also sourced all the biomass myself from two local farms, dropping literally hundreds of invasive buckthorn and honeysuckles as well as aggressive “weed” trees such as red mulberry and box elder over a week and then renting a 27hp Vermeer chipper to grind them up.  It was awesome!

This post is pretty epic itself – I opted for smaller photos in the post to keep the overall post length a bit shorter – click on them for a 600×800 shot.   This really should have been 2-3 posts, but I spent more time working than writing.  Skim or read it all the way through at your preference.  Total work covered in the build is 3 weeks, with another 1.5 in the biomass acquisition.  These are “puttering” time lengths – I am always working on 4-10 projects at a time :).

With the material on site it was time to get it soaking.  One of the keys to Jean Pain style brushwood composting is to soak the material for 2+ days to ensure that the chips are saturated to supply the pile with enough water to sustain it for months.  One of the problems I ran into early on is that of scale.  I can only soak about 6 yards of material at a time, which limited me to 1.5 batches a week with my days off and the shorter daylight of Fall.  All told it took over 3 weeks just to soak all the material.

Giant 375 gln (1420 l) totes I bought off of craigslist a few years back for $25 each. Why? Why not!

Once the material was soaking it was time to prep the ground.  I spent a day spreading the old Midden around the gardens.  This was unreal – never before have I had 8+ yards of compost to spread all at once.  EVERYTHING got mulched.  Yes, spreading compost by the wheel barrow load (40 of them!) is as fun as it sounds.  I will say it again and again – COMPOST is the true point of the Middens – gathering energy from them is merely function stacking an intrinsically useful activity.

As this pile was going to be 50% larger I had some concerns about it breathing well.  At one point I had myself talked into laying out 4″ perforated drain tile for air circulation, but thought better of it for several reasons.

Cupplant, Sunchoke, and Sunflower stalks forming the passive air circulating foundation to the Midden. After the winter it turns into humus and sequesters carbon. Regenerative waste stream? Check.

First – it added expense and resources.  I like to keep the plastic to a minimum; while not afraid to use energy or resources for the Greater Good, I also like to use natural products whenever its feasible.  Second, Jean Pain never did so I’m not even sure its necessary.  My solution was simple – I cut down a half dozen Cupplants that were nearby in the prairie garden that serves a insectary habitat near my permaculture guilds.  The thought is that these will allow air to come in slowly from the under the pile as they decompose themselves.  Basically the same reason you are often told to put twigs under a normal passive compost pile.

Now, the observant amongst you will notice a piece of .5″ conduit stuck in the ground with a tape measure  in front of it.   Of course there is a very good reason for this.  The Midden LC will have a 3′ (1 M) diameter core of brushwood that will be wrapped with 1″ tubing, but I am getting a bit ahead of myself.    With the base down, it was time to get building.

The Core

The core diameter of 3′ was chosen for the simple reason that hot composting seems to benefit from a minimum dimension of at least a meter.  Build a pile smaller than this, and you won’t get hot enough.   One of the downfalls of the Methane Midden is that the layout forced a width of only 2′ in most cases.  I thought that the straw bales insulation would be enough.  I was wrong.  Back to basics then.  Getting wood chips to form a cylinder can take some doing.  Luckily I had enough 2′ garden fencing in the garage to make a “mold”.  The thought was to cut the fencing to the circumference of a 3′ diameter circle.  Time for fun with math!

4' (1.2 m) tall Core. As I unwrapped the fencing, I would wind 150' (45 m) or so tubing around the chips to keep them in place.

A circle’s circumference is Pi x the Diameter of a circle; 3.14 x 3′ = about 9.5′.  Done.   Now, when you cut the fencing – leave the “nubbins” on the cuts – this works well to fold around once you get the circle made – think giant velcro.  The conduit I stuck in at ground zero and measured 18″ off each side to center the core column.  Then it was simply a matter of schlepping in the soaked chips.  About every 8″ (22 cm) or so I tamped the chips well with a 12# (5kg) sledge hammer.  Once I had 2′ tamped in place, I unhooked the fencing and unwound it.  Thanks to the tamping, the chips stay in place very well.  I then wrapped the fencing on the top of the cylinder with about 2″ (5 cm) of overlap on the bottom.  Then I started wrapping the heat exchanger around.

I love this shot. It really shows how stable the chips are with tamping (walking on it at this point). Jean Pain didn't use molds, just slapped it all in place with a pitchfork and walked on it.

This progressed 2 times until the core got about 5′ tall.  At this point I was becoming somewhat concerned that the column could topple, despite how stable it seemed.  Redoing it at this point would SUCK, so I opted to switch gears and work on the outer “donut” of biomass.  The thought here was to again use the 1 meter width of material to maximize the bio-reaction of the thermophilic bacteria.  Having 3′ of material on each side of the exchanger giving the Midden L’eau Chaude a total diameter of a bit over 9′ (2.75 m).  The other important reason to start building out the “donut” was that stacking, and especially tamping, the Core was getting difficult as it was over shoulder height for me at this point.  With a 2′ tall rim around the Core I could bring it up to its goal of 6’+ bringing the total heat exchanger length to over 550′ (168 m).  The heat exchanger needs a bit of explaining since it is critical to the Midden, so here goes.

The Heat Exchanger

550′ (168 m) of 1″ (2.5 cm) polyethylene irrigation tubing. Never one to be modest… this is a work of art.

This is the finished heat exchanger and I won’t even try to be modest.  It’s GORGEOUS!.  The water will come in the bottom, spiral up for 6′ and then take two larger loops back down to exit the pile.  Why this way?  It has a lot to do with temperature gradients.  Heat transfers best the larger the temperature differential (delta T).  The final goal is to that the water entering the pile at about 80 F (26 C) and exiting north of 120 F (49 C).  The bottom of these piles are cooler (heat rises!), but will still be rather warm.  As the water in the exchanger warms it is also climbing up through the pile, which is also getting hotter.  The thought is that there will always be a delta T of 20+ degrees between the pile and the water in the tubing.  Slick, huh?  Now wth is up with the big looping spirals?  The poly tubing kinks somewhat easily, so I chose to take 2 revolutions to expand the diameter of the spirals and slowly increase the degree of bend up to my final exit point. Now some final thoughts on the exchanger.  First, I would shift the hole thing up a foot.  Starting 4″ from ground level like I did will not add much heat to the water, whereas there is over a foot above the top of this column now that I am done.  I had thought that the top would be cooler, but that is not the case – no matter how much I pile on the heat just comes right through it: put your exchanger to within 6″ of the top without fear as long as the pile is hot.  Can you see I am already planning Midden #3?  But for now we need to bury that exchanger. Fleshing out the Midden


Taking shape! This is about 12 cu yards ( 8 cu m) with a current height of 5.5′ (1.7 m) and a 9′ (2.7 m) diameter. Awesome.

To keep the pile nice a tidy, and also to ensure that I could still walk around it, I again used a garden fence mold for the 9′ (2.7 m) diameter “donut”.  this time I opted for 3′ tall fencing.  The outer section takes an immense amount of material to fill – it was almost 2 weeks to get it to this point as the pile at this point was over 12 cu yards and weighed over 6 tons due to the sopping wet chips.  Remember that I could only do 5-6 yards at a time as the chips had to soak for several days.


I had intended to unwrap and re-wrap the fencing again, but in the end chose to leave it on and switch again to an insulating rim of straw, which I ended up stacking 3 tiers high.  It gets significantly colder here in southern Wisconsin than in Jean Pain Provence with winter lows dropping to -15 (-26) at least once or twice.  Time to break out the dump truck again!  Back to Craigslist and I contacted a farmer about 4 miles away with 70 bales of Oat Straw.  I would need about half that for the Midden, but filled up the truck to mulch the beds as well.

BART holds 48 bales of straw. I am not saying *everyone* needs a dump truck. But in my case I am making a good argument..

With the straw in place around the fencing, I then stacked a third tier of straw to form the mold for the final several yards of material.  In the shot at right the pile is nearing 7′ (2.1 m) tall which was the goal.  At this point I was nearing the end of the biomass and began to focus on rounding out the pile and maintaining the 3′ length from the heat exchanger as much as possible.   Was incredibly pleased with how the Midden was literally shaping up.  Sometimes a project just CLICKS.  This was one of those!

Gap left for the pump installation. You can FEEL the heat coming from the pile, the core of which is 150+ (66 C) at this point. Dang sucka.

Jean with one of his piles. As you can see his heat exchanger loops would have gone around the OUTSIDE of mine. Then again his piles crested 80 tons - 10x as big as mine. Jean was a visionary, and I am honored to be able to promote his work for a new generation.

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Methane Midden – La Fin


The Methane Midden got a ton of press for its attempt to produce energy from brush.  And in a suburban backyard no less.  But as I spent the day Tuesday finishing its tear down I was struck by the need to set something straight.  While the goal of the experiment was to try to produce methane (and hot water in the new Midden), the goal of the system is, and will always be, to make an insane amount of compost.  I routinely trailer in over 10 tons of organic matter, mostly woodchips, each year to my .5 acre ( .2 HA) lot and my soils are still far from done.   Our urban soils are incredibly denuded in most cases, and until the organic matter content gets up to 5%+ in the top 6″ of soil we have a ton of work to do.  And in this region, topsoils used to be 6-10 FEET thick (2-3 m).  To add 1″ of compost on even .1 acre you need 13 yards of compost.  It is mind numbing to think about how much compost and mulch we need to heal the soil of our cities.  Luckily all the carbon we need is unhappily sitting above us in the atmosphere.  Hence my desire to cut down coppice and compost it.  Putting our tea bags in a bin won’t cut it.  The fact that I am working to get energy out of the piles is a fringe benifit.  A really, really cool one. 🙂

The break down of the midden was not sexy, but it was awesome none the less – 8 yards of compost, all at once, is simply staggering in what you can do with it.  The “compost” was really only about 75% done due to the amount of pine needles, it was really a well cooked mulch – very similar to the “duff” layer in a forest.

Rather than bury you with text I will tell it in pictures.  Enjoy:

Cut away of the Finished Methane Midden. The layers of heat exchanger settled over 50%, with the bottom two resting on the ground. Not good - time for a redesign.

What a mess. And you missed all the swearing to get it to this point! Anyone need any yellow garden hose?

Then I started spreading the mulch.  The plan was to use the finished compost to start my willow/poplar coppice that I will plant in Spring 2011.  It is sized for about 80 trees and will have an understory of Russian Comfrey.  Will likely also put in some False Indigo and everbearing raspberries, but I get ahead of myself!

The coppice will be around 3 sides of our kids playground and will have a total row length of about 125' (22 m). This side is close to our fence and is only 2' wide -enough for 1 row of trees..

Good shot of how thick I laid the mulch down here - easily 4-5" (10-12 cm). This is the main width - about 4' (1.5 m) for a double row of willow. Thanks again to author Michael Perry for his help with this during his visit!

The final leg of the coppice to be. Yes, I have 2 wheel barrows... I also have 5 pitchforks - and each has a specific use! So much mulch, and I hadn't even used half the pile yet...

This post may get long, but I really want to pound home the shear amount of Good Work that can be done with one of these Middens – I was beyond giddy driving my barrows around the yard flinging compost at anything that grew! Plus it is a compost eyes view of much of my permaculture beds.  I have been asked if I used more energy than I created with the Midden.  Yes, I did.  But show me an oil rig that can do all this:

'Barrow load under my sole bamboo - a clumper. This will be its first winter -fingers crossed!


Mulch spread in my Asian Pear tree guild - I forked it around the perennials so as to not bury the groundcovers

Wheel barrow load of mulch for my sole apple tree. It speaks volumes that I spread most of this compost "by the wheelbarrow load" rather than the forkful. AWESOME! This still needs to be spread away from the trunk.

7-8 barrow loads went on my Sunchoke plantings. Sunchokes are not my favorite food, but this reliably cranks out 50#’s of food for no effort.

Here is the raspberry patch. It was rather overgrown so I hacked it to the ground and refreshed the soil with 8 barrow loads of Midden Mulch. Still not even 75% done with the pile!

Into the Guilds! Mulch under my heirloom Pear - a White Doyne which I have never seen in a catalog, but got from a nurseryman friend.

The other portion of the Pear Tree Guild. This shows one of my Paw Paw's, some hazelnuts, another pear, and a hardy kiwi on the fence. 3-4 more barrows here.

I had so much mulch I decided to start a new guild. This is a pine I bought the year we moved in and is just no starting to grow. In went an elderberry, some thyme, a service berry, and several dozen strawberries. And yes, I just had these lying around...

Mulching under one of my front yard "pretty" guilds, both Peach Tree guilds.

It was so incredibly liberating to be able to spread compost where ever I wanted to – flinging forkfuls into the rain gardens, into the prairie, on the lawn – without have to choose which plants to favor and which had to go without.  Also notice that my annual vegetable gardens didn’t get any mulch.  This was intentional – this mulch is very carbon intensive at this point, and will be heavily skewed to fungal decomposers which my perennials prefer.  The veg garden would have been fine, but the fruiting shrubs and trees would really benefit.  Plus I have another 5 yards of compost in my regular bin for the veggies.

The Methane Midden was lined with over 20 bales of straw. These were a wretched mess... perfect for a winter mulch for the veggie gardens!

Now the Methane Midden has passed, but OMG will it live on.  I covered everything in this post, plus 3 other guilds, 2 rain gardens, and even some into my mini prairies.  Imagine what your gardens will look like if you built 2-3 of these Middens a year?  I can’t wait to find out!

Energy is fantastic and very useful up here where it gets to -15 F (-26 C) in the winter, but being able to make this much compost, from invasive species and “weed” trees is where the true beauty is.

Over 8 yards of compost from one pile in the burbs?  Epic Shit indeed!

And I can’t wait to do it again – only BIGGER.

Be the Change!


Methane Midden – Learnings

June 2010

The Methane Midden was my first attempt to recreate, on a significantly smaller scale, Jean Pain’s Epic Compost piles that he used to heat everything from his house, to greenhouses, to sheds, and he even buried methane digesters in them.  He worked on these projects for over a decade and did some truly Epic Shit.  The dude was a bad ass and a Bioneer extraordinaire – and he did all of it 40 years ago.   My Methane Midden didn’t produce any capture-able methane.  Why?  I screwed up the PH, screwed up the solids:liquid ratio, and was doing 4 other projects at the time and didn’t focus on it as I should so missed both of the above, or at least failed to address them.  But that is ok, because when you screw up, you reap a boat load of learnings. So it was with me.


  • Spend more than 30 minutes planning a project. A full third of the issues below were foreseeable and I could have caught them.  But that material was decomposing with every minute I delayed, and/or some other guy could have grabbed it.  I struck when the iron was hot.
  • Rubber is a crappy heat exchanger. Duh.
  • Looping hose through a pile haphazardly doesn’t work real well as an efficient heat exchanger.
  • Digging out said looped hose sucks.  Jean Pain figured this out early on, and switched to an elegant solution.  So will I…
  • 540′ (164 m )of garden hose only holds like 40 gallons of water (151 l) , which at 6 glns/min (15 l /min) only keeps the water in the pile for like 7 min. In rubberized tubing.  Yeah, THAT is going to heat up…
  • Rectangles are stupid. The bio-chemical reaction that happens in composting works as a sphere.  Rectangular piles waste 20%+ of the composting material as it never hits prime temp.  ALL of Jean’s piles were cylindrical (ish).  Rectangles… easy to build, crappy in use.
  • Putting large tanks in the middle of the pile screws up the reaction.  Again, the reaction in a compost pile needs about 3′ (1 m) of width (in all directions) to achieve critical mass.  The 2 digesters in the middle of the Methane Midden meant I only had 2′ (60 cm) of compost materials on each side of the digesters.  I thought the straw bales would provide enough insulation to overcome this.  I was wrong.  Jean Pain’s piles were HUGE and over came his buried tanks with shear volume – he had 9′ (3m) of material on each side of the tank – more than enough apparently.
  • Hot Water or Methane.  Choose One… At the size I was building, I would either keep the methane digesters at 100 degrees (38 C) or heat the water to 120.  I couldn’t do both without separate heat exchanging systems.  Jean Pain had 400 meters of  2″ hose (1200′) so his first 100m (300′) went around the digesters to cool them, and then he had 300m  (900′) of exchanger left to heat up.  I can get an exchanger that big in my piles, but not with a digester in the middle.  Hence the L’eau Chaude pile
  • Pine Needles don’t really work. The Methane Midden came into being because some local guy limbed up a huge amount of pine trees – there was no other time I had seen so much “green” brush all at once.  Pine needles have nitrogen, so the pile heated up, but they also have alot of resin in them which ultimately blocks decomposition.   This meant the pile died after 2 months, where I suspect a deciduous based feedstock would have gone for twice that long.   The compost didn’t really finish, ending up as a humusy mulch, for this reason.  I worked with what I had and learned a ton – like I need to source my own material, and also what happens when you pile up 10,000 #’s (4500 kg) of chipped white pine limbs (140 degrees for 2 months, then 100 degrees for another 1, then ambient)
  • Jean Pain style Brush Composting Works. While dismantling the Methane Midden this week I didn’t come across any anaerobic sections, and the pile was still damp.  After 5 months.  Soaking the material for 2+ days adds enough water to sustain the reaction, and the large particle size of the brush provides enough bridging to let air in.  On paper / first glance composting this way is insane.  But IT WORKS.  I still need to figure out the proper C:N ratio – higher on the Carbon side than a traditional hot compost pile to sustain it, but more Nitrogen than the Methane Midden had to keep it going longer.  I ran several smaller experiments over the summer and they tell me that .5-1″ (1-2 cm) trunks of brush with full leaf should be ideal: thicker trunks, say 2″, and the pile die quickly, to thin or brushy (mature lambsquarter) and the pile goes into runaway mode – hitting 178 F (81 C).
  • Green wood is important. It is precharged with moisture, and the sap is sugary.  Bacteria like sugar…  Mixing a pile with dry, dead chips and leaves and you would need far more water –if you can even get enough into the chips- and alot more leaves, leading to matting.  Luckily the vigorous willow strains such as salix dasyclados will put up .75-.875″ rods in one year of coppice growth.  Just sayin.
  • 8 Cu yards of nearly done compost will turn you into a glutton Will explain tomorrow, suffice it to say virtually EVERYTHING in my yard got a 1-2″ (2-5 cm) layer of humus rich mulch!

So, the new Midden is underway.  It will be hot water only, and it will be cylindrical.  It will be made with primarily made from deciduous plants.  There will be no tanks, and I am upping the tubing to 1″ ID.  There will hopefully be as much as 900′ (300 m) of it if I can find some more compost material.  That should increase the volume of water in the pile by a factor of 10.  Also may purchase a new pump that will drop flow rates to under 2gpm, potentially keeping the water in pile for over 2 hours rather than 8 minutes.

Work is happening faster than I can type up posts, though expect a flurry in the coming weeks.  If you want to keep more up to date, I will be updating Facebook more frequently with mini reports.  This is going to be awesome!

Be the Change!


Coppice Compost Harvesting

More to come soon as I do a proper write up, but here are some links I thew on Faccebook from today’s Coppice Harvest which netted just shy of 15 cubic yards – about 6000#’s.  Holy crap was this a fun day.  Broke the hitch mount off the dump truck and I barely even care.  The Vermeer 600XL chipper is bad ass.  Its also more tool than this project needs, but figuring that out was one of the reasons I rented it.  Thanks again to Chris and Mark from work for helping me out!



And thanks to coppicing, no trees were killed in the making of these videos!


Introducing Midden Part Deux: “L’eau Chaude”

Right.  So the past 2 weeks I was out of country – 6 nights in Victoria, Australia in the Great Otway National Park and then 7 nights in New Zealand 3 nights in Kiakoura on the South Ocean and another 4 getting to know Wellington.  It blew my mind and I am in no condition to post about it yet – still fermenting.  But time waits for no man, and with the leaves falling it is almost past time for me to get my arse in gear and build the second midden.  So here goes.


Introducing my Husky 235. 1.8 hp and I dropped and limped 3000#'s of biomass on a .25 cups of fuel. Efficient? Can I get a Hell Yeah? Wear your safety chaps, the femoral artery waits for no man.


First off, this midden will have several differences.  The first, of course, is in intended use.  This Midden will be designed to produce hot water (l’eau chaude) v. the Methane Midden’s failed attempt to make methane (botched the PH and ran out of time).  Second, this the Midden L‘eau Chaude will be constructed with freshly harvested brush.  That means a few things.  Like I needed to find 8000#’s of brush and that is a bit more than my backyard can supply.   Oh, and I need some new tools like chainsaws.  And finally I need a Big Az chipper.  How does a trailer mounted 27hp Vermeer sound?  It sounds kick ass to me as long as no one goes Fargo…  Renting the chipper for now, but if this works, I can see a huge shredder in my future.  Someone has to figure out how to run these on ethanol and methane, right?  Perhaps…  that shredder runs $8k.

We’ll get into the technical pieces of the  l’eau chaude in future posts, but for now, lets talk through sourcing the brush.  I called some of my friends that own land and was able to secure enough material in no time.  It isn’t hard to wonder why.  Say you own 20 acres, 10 is in woods.  You get a call from a friend who is offering to cull invasives from your woodlot.  For Free.  Oh, and he’s going to use the material to do some Epic Shit.  Done deal.  I have 3 lots that I am working on this week.  The plan had been to drop a bunch of Box Elder since it grows 6-10′ a year here and can be invasive, but that has run into some hitches.  First, they are dropping their leaves, and I need the leaf nitrogen in the Midden.  Second, the main wood lot was cleared of Box Elder a decade ago.  Huh.  So the land owner and I walked his lot and it became very obvious that there was plenty of species still in leaf, and the sources were, if anything, even better: buckthorn and honeysuckle which are wicked invasive in this area.

As we were felling these, I became worried that there wasn’t enough green material in the mix – the honeysuckle especially was only leaved on the ends of the trunks due to the dense canopy, and most of the buckthorn we were dropping was crazy mature – we had some with 7″ trunk diameters!   Looking around some more we noticed that mulberry was still in full leaf and they are a very aggresive tree in their own right.  Out came my new Husqvarna and we dropped several 7″ trees that were leaning over his paths and would become issues in the next decade.  These were limbed up, with the trunk being lopped up for firewood.  tomorrow, at the property where I market garden we will be dropping a HUGE mulberry that is shading a vegetable patch with the same technique: limbs into the Midden, and the trunk wood will be used for space heating.

The honeysuckle, small buckthorn and mulberry look exactly like the shrubby brush that was coming out in the Jean Pain videos.  Still TONS of trial and error to be done here, but it looks like 1″ or less trunk diameter is the money width for composting.  The 3 bins I have going at home were built using 1.5-2″ willow and are far too carbon rich; I needed to add nitrogen at the first turning.  1″ trunks would be a 2 year rotation in a willow coppice.  I have no idea what pushing a coppice that hard will do, but it is likely it will burn it out in 5-10 cuttings.  That said, I was cutting mulberry out of the landowners asparagus “patch” (its .5 acres) that was 6-7′ tall and has been mowed every fall for 15 years.  Those stalk were ideal.  Hmmm, with stalks that small harvesting gets easier.  How about a mulberry/willow/poplar coppice on 12″ spacing and a 25hp straight veg sipping Kubota (sunflower stalks compost FANTASTIC) pulling a two row Gehl sillage chopper…  Those things are dirt cheap on Craigslist as no one uses such small equipment any more.  Huh.

But for now I am focusing on harvesting from the woods.  With about 6 hours of labor in, we have 8-9 piles of brush larger than the dump truck, and Friday I am putting in a full day now that my sawing muscles are hardening and felling a significant amount more.  Tuesday will be the final day of prep, and the rental chipper gets picked up on Wednesday at 7am.  Goal is still for 2 loads, 8000#’s, of green material.  These will go into the plastic tubs for soaking, and then construction begins on Tuesday 10/19!  Pics will be up tomorrow night on the brush hogging.

Can we turn the invasive species of today into the carbon sequestering, energy and food producing fuel stocks of the next century?     Stay tuned.

Be the Change!


Midden Mini – Update

Finding it extraodinarily hard to find to time to write with everything thats going on (tours, workshops, Real Job, kids home, potato harvest, epic vacation planning)  but The Good Work is not suffering.  This post will be text only as I don;t have time to upload and edit the pics.

The main updates on the ‘Midden are that the pile is cooling – down to 110.  That is due as much to its age as to me tearing into it every week to tinker with the, now, primed digesters.   So lets talk about those digesters.  2 weeks ago I filled one of the 55 gallon drums with ground up box elders, and the other with ground up lambsquarter.  Why?  Both plants are prevalent and rather despised weeds hereabouts.   To those not sharing the local stereotypes on plants, that means that the biomass from those two plants can be had for free and in large amounts, or in the case of box elder, one can be paid to remove it from woodlots.  Nice.

The side by sides were to see if a more carbon rich (box elder) feedstock would screw things up.  Goal in biogas production is to shoot for normal composting C:N ratios of 25-30:1.  The box elder was likely closer to 40-50:1, the lambsquarter more like 20:1.  Jean Pain never measured, and I like flexible systems.  We *know* 25:1 will work, so lets push the envelope to see what happens.  Unfortunately, 2 of my 3 steel drum lids had the bungs rusted on (snapped a bung wrench trying to open it) so I can only seal one.  I choose the Box Elder.  Weeks went by with nothing.  Temps are good – 90-100 with digester feedstock at 95.  I should be cooking right along, but wasn’t, or if I was I wasn’t capturing it.  That meant I needed to reseal the barrel as the old gasket was, well, old or that the chemistry had gone wonky.  I sealed the barrel up with silicone and then I took a sample to a friend with lots of lab equipment including pH testers that give near instantaneous readings to within .01.  Results – the Box Elder batch was sour.  REAL sour : 4.8 !  Methane microbes like to be 6.8-7.4.  Oops.   Making methane is a delicate dance between acid producing bacteria and methane producing ones.  I don;t know enough about the bio-0chemistry, but my hunch is that the prevalence of carbon in this digester tilted the balance, but there are so many variables.

So I stopped by my friend who runs our local sewer utility and picked up 8 gallons of biosolids – the left over treated turds of our village.  Our municipality sterilizes the processed effluent with lime as not many bacteria live past a pH of 12.  So the left over solids are about 10.4 pH and are still high in organic matter.  3 gallons of slurry and had me up to 6.1 pH, so I threw in another 2 gallons and will test again tomorrow.  I also threw in another cu ft or so of compost to reinoculate it.  Why?  Because I have come to the same conclusion as Will Allen at Growing Power – that compost fixes nearly everything microbial- if you throw 500 billion bacteria, spread across 15000 different species it is rather likely the one you want is in there and will thrive if you set the environment up.  Fingers crossed.

Back to our story.  When I went into the lab today, I also tested the lambsquarter digester for pH.  This unit had a different odor to it, less sickly sour and more of a deeper, more robust putrescence.    It was also bubbling under the slime.  Huh.  Could that be methane?  The pH test of that looked much better – 7.10!  Right in the sweet spot. So I switched over the methane capturing lid and now the lambsquarter digester (#2) is sealed and plumbed to collect gas.  Perhaps I will have video up soon of itty bitty bubbles coming out the discharge tube.  If so, I will capture some and take them back to be tested at the sewer utility as they have equipment to test for methance gas quality.  And since I am using their Biosolids-  I now qualify as a test project so I get to use all their toys.  Awwww yeah.

Also staking out felling rights to several local woodlots and will likely be buying a chain saw or a wicked good axe to take down several hundred 3-5 yr old Box Elders for the next phase of the ‘Midden as we switch gear for hot water production, perhaps in September.  Problem is I will be out of town for half the month and I lost my “intern” to school so not sure if I want to start it before or after.  We’ll make it work.

MUCH more to come!


Food + Fuel + Fertility = The New Paradigm

Food. Fuel. Fertility.   Of late, those 3 words hammer through my brain like a sledge whenever I get going on a new project.  The reason is simple – I am convinced that our agriculture has to do all three if we are to build a new culture to survive the new reality of Climate Change on top of Energy Descent and our burgeoning billions.  We talk and talk of sustainable culture – but I don’t want to sustain what we have now – the fear, the pollution, the waste – I want something far better.  We need a Regenerative Culture. The Age of Exploitation must come to an end – the Age of Healing has arrived.

The Methane Midden is a good example of this thinking.  While significantly on the energy/fertility side with its 4-6 months of hot water or methane on top of the 4000#’s of compost, it is also planted with squash and tomatoes to produce hundreds of pounds of food.  The system is still being tested (the plants aren’t loving it) but the potential is immense.  7 weeks in and the pile is still over 125 degrees – with no turning or maintenance at all.  Dang!  Tomorrow I am going to harvest several hundred mature lambsquarter that are 9′ tall to be shredded for the methane feedstock.  Much more to come on that project!

With that task of harvesting tall stalky plants in the back of my mind, this morning over breakfast I went on a fantastic internet fueled thought tangent on the feasibility of a fuel tweaked Three Sisters guild.  It is so simple, which is why I am so excited.  First – take the standard Three Sisters of corn + pole beans + winter squash and swap oilseed sunflowers for the corn.  Why?  Because my car and 2 wheel tractor run on diesel.  Journey to Forever says that you can get 102 gallons of oil from an acre of sunflowers – 43,000 plants on 1′ spacing.  But we are wanting a polyculture so we will need to let some light in by spreading the sunflower canopy a bit – say cut the spacing in half to 25,000 plants or so.  That still leaves enough plants for 50 gallons of oil if we use oilseed varieties.  Then take the understory and add back in the squash.  Monoculture will get you 10-20 tons of squash per acre.  So again, lets cut that down a bit and say 18,000#’s.  That is ALOT of food.  Food that keeps all winter long. Finally, we are vegetarians so we needs our protein.  Add in the soup beans.  25 bushels per acre is typical @ 60#’s a bushel.  Again, cut in half for polyculture and you get 12 bushels of beans, or 720 pounds.  So to recap our acre is now growing enough seed to produce 50 gallons of oil, 18000#’s of squash and 700#’s of dry beans –both of which keep for months and months.  That is rather good.   Lets make it better!

Remember the thought stream that got me to this point over my now cold steel cut oats.  Chopping down cellulose rich tall plants for methane fuel stock and compost.  25,000 8′ tall sunflowers…. lay them down end to end and its over 37 miles.  I haven’t weighed one, but figure they weigh 5#’s each.  That is 62 tons of green material that is going to be pretty close to perfect C:N ratio by harvest time.  125,000#’s of material – composted down with a 75% loss gets you to about 30,000#’s of compost, or 55 yards.  That seems high so I would love to prove the math.  That is enough to spread the entire acre with .4″ of compost- a very healthy amount and far more than I apply annually in my market gardens.  Fertility would increase to say the least.  62 tons of material would also be enough to build 8 Methane Middens so that we can heat our winter greenhouses or the chicken barn.  Dang sucka.

Back to the fuel part again.  50 gallons doesn’t sound like much.  And it isn’t.  Most of us only get 22 mpg and  drive 12000 miles per car per year – 540 gallons per year per car.  Ouch.  But we all know that we will drive ALOT less in the future and most cars are fuel hogs.  My VW TDI gets 42 MPG towing a 1000# of cargo in my trailer.  Have I mentioned I love my car?  So, even saving 5 gallons for the Grillo to till the acre, we still have enough oil to drive over 1750 miles towing all those squash and bushels of beans to market.    If we relocalize that is 175 round trips to town 5 miles away – 3 trips a week. Huh.

But I want to re-stress my loathing of the food v. fuel argument.  It is a farce if you think it through and know the science of biofuels-even ADM fed their ethanol mash to tilapia.  So we take the 25,000 sunflowers, grind up the seeds (will need some energy there – unless we build a bicycle machine to do it), and press them.  That seed mash left over from the pressing doesn’t just disappear.  In fact, about 50% of the total oil is essentially impossible to remove from the pressed seeds without solvents, and the protein and carbohydrates are still there too –i.e. the food value of the seeds is still there.  That means you still have 1500#’s of protein rich (40%) meal to feed to your livestock.

Can we rebuild the next 20 years to allow us to transition to a less energy dense future?

1 acre nets 18,000#’s of squash, 750#’s of dry beans (4500 cups cooked!), 1500#s of animal feed, 30,000#’s of compost after you have heated your buildings with 8 Methane Middens worth of energy, and you also managed to make enough oil to power the tractor and drive to town 3 times a week for the next year.

On one acre.

Be the Change!


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