Saturday, May 10, 2014

The Cone Pit Method

"We wondered, before going to the expense of building a steel wok like they use in Japan, what if we build a pit like Josiah Hunt but shape it like a cone kiln?"

Charles Eisenstein, writing for Resurgence, says:
Please, my argument here is NOT “Various greenhouse-gas curtailment schemes have failed, so we shouldn’t even try.” I am, rather, proposing that these failures have something in common – they emphasize the global over the local, the distant over the immediate, the measurable over the qualitative – and that this very oversight is part of the same mentality that is at the root of the crisis to begin with. It is the mentality that sacrifices what is precious, sacred, and immediate for a distant end; it is the mentality of instrumentalism that values other beings and the Earth itself in terms of their utility for us; it is the hubris of believing we can predict and control the consequences of our actions; it is the trust in mathematical modeling that allows us to make decisions according to the numbers; it is the belief that we can identify a ‘cause’ – a cause that is something and not everything – and that we can understand reality by dissecting it and isolating variables.
What would happen if we revalued the local, the immediate, the qualitative, the living, and the beautiful? We would still oppose most of what climate change activists oppose, but for different reasons: tar sands oil extraction because it kills the forests and mars the landscape; mountaintop removal because it obliterates sacred mountains; fracking because it insults and degrades the water; offshore oil drilling because oil spills poison wildlife; road building because it carves up the land, creates roadkill, contributes to suburbanisation and habitat destruction, and accelerates the loss of community. On the other hand, many of the technologies I find beautiful might also be justified on climate change grounds: agricultural practices that regenerate the soil; restoration of forests and wetlands; smaller homes in higher density communities; economies of reuse, upcycling, and gift; bicycle culture; home gardening.
Yesterday our 2014 ecovillage apprentices, still caked with clay plasters from upcycling our Prancing Poet Ecohostel, helped us perform an experiment we have been inching towards for a month. Like most experiments, there was no real success or failure involved, just the harvesting of new knowledge. Still, we were grateful that it turned out even better than we had imagined it might, and now we are eager to pass along the results.

The problem we are addressing is multilayered. At its most general layer, there is an observable imbalance in Earth’s climate systems that is an existential threat to all of us.

... and lift-off
We attribute this imbalance, now calibrated with a high degree of certainty, to the corruption of “normal” atmospheric chemistry with a superabundance of waste elements from the biological processes of a single, invasive, overly fecund species, you know, the two-legged ones. Since this species shows no sign of going away before it causes irreparable harm to its host, we few revolutionary cells, acting as antibodies in the greater system, are working towards effective and timely mitigation by finding ways to reduce and reverse the damage wrought by our deluded or disengaged brethren.

The dilemma is, as Eisenstein opines, global, distant, distressingly measurable, and spawned by hubris that is seemingly intractable. Nonetheless, the way out is beautiful, elegant, sublimely local and relies on millions of farmers and gardeners awakening like a peasant permaculture army and simply doing what they do best — grow food.

One of the most promising (and most tested) ways we know to reverse the effects of runaway source emissions is to increase the strength of nature’s counteracting sinks. At the planetary scale, carbon has four mega-repositories: deep earth (including fossil hydrocarbons); shallow earth (topsoil and the subsurface microsphere); oceans; and vegetation. Deep earth is where half the problem originated, but returning carbon there once it has gone to the atmosphere, while technically feasible, is stupendously expensive (as we described here two years ago). The Ponzinomics of “clean coal” scrubbers, or artificial trees, may yet provide windfall profits for the 1%, but it comes at the expense of everyone else, and all our relations.

Oceans are the sink that has shouldered the greatest burden for the past century or more, but even oceans have reached their unfathomable limit and now, as they warm, not only will not accept more from us, may join us as fellow sources. Oceans, while remaining net sinks, are already starting to return excess carbon back to the atmosphere through methane effervescence and plankton die-off. This is a frightening, self-reinforcing feedback demonstrating all too cogently the penalties of our dalliance. Soon, only two viable sinks will remain — shallow earth and vegetation — to pick up the slack and get us back to 350 ppm or below.

We need to net sequester from 5 to 10 gigatons (or petagrams, or billion tons) of carbon annually to dial back the danger as quickly as we can. The only way to get plants and soils to perform that trick is to baby them with water, healthy microbes, and TLC. Burning soils with chemicals just adds deserts, to say nothing of driving the nutrition out of food. We need more organic gardens, more forests, and also — something that would assist in the creation of both of those first two — more biochar, or recalcitrant carbon, to work as an alternative to petrochemical fertilizers while intercepting short carbon cycles and replacing them with longer, slower, more earth-friendly ones.

For the five billion people on the planet who grow food, and the six billion who work in some fashion with the more than 50,000 species of bamboo, this is good news.

Growing Local

Each type of of biomass provides a unique cellular signature
At the Ecovillage Training Center, the apprentices have been busy since early March harvesting all of the dead culms of our bamboo left by an exceptionally harsh winter. Not all varieties are the same — some have lower temperature tolerance and did just fine, while others froze and died back. Having a wide variety is an excellent hedge for any grower.

Bamboo is the second fastest growing plant on Earth, after microalgae. It will double its biomass every year if conditions are right. Running varieties can expand as far out from their base in one year as they are tall, and do it again the next year, and the next.

Building a bamboo fence

The first use we made of our Spring bamboo harvest was for fencing around our poultry area, enclosing the chicken coop and duckling ponds. The second use came from taking the slightly larger widths — 2 to 3 inches in diameter — and splitting them to make plaster lathe for the building we are currently reviving. Some prime pieces ended up as walking sticks, garden stakes or finishing trim — or future bambitats — and then, finally, what was left became the scrap pile — whatever odd shapes and sizes were without immediate other uses — and that was set out to dry. It is now early May and that pile was sufficiently large and dry — 12 cubic feet — that the time had come to turn it into biochar.

Building a bamboo building (Pachamama, Colombia 2013)
We have been adding biochar to our gardens since 2006 and we swear by it. Bamboo biochar is especially great, because those big pores in bamboo’s cell structure translate into a heavenly microbial habitat when it is charred, charged, and dug into the garden. Just by way of example, we had a Discovery Channel crew here shooting a piece on biochar stoves in mid-March. We had a dozen small tomato starter plants — no more than 3-4 inches tall at the time — that we filmed being transplanted into 1-gallon containers. The lower half of the container was composed of biochar that had been steeped in urine for the previous 4 months, then turned with a mix of weathered sawdust, kitchen compost and composted horse manure before being deployed as container fill. The top half of the container was just the tiny, fragile tomato plant surrounded by garden soil.

Bamboo cup
Too bad the Discovery Channel was not able to return 4 weeks later, in mid-April, when we moved the tomatoes from the greenhouse out to our garden beds. By then they were chest high, all leafed out, and in need of stakes or cages to support their weight. No MiracleGrow or other synthetic fertilizers were used in the making of this testimonial. Just biochar from bamboo and a little compost.

Yesterday, with storm clouds gathering from our Southwest, we decided it was a good time to take the dry bamboo to the kiln. We could not get any more solar drying done this week and the summer garden will be wanting more biochar soon.


We have experimented with a number of stove designs, from oil drums to TLUDs, Beaners and Biolites to ceramic ovens, but lately we have been most intrigued by the large wok design used by the Hozu farmers cooperative in Japan to turn bamboo into biochar for their “Cool Vege” label.

Our friend Kelpie Wilson out in Oregon made one of those “cone kilns” and reported the results on her blog. In January she traveled to Simi Valley, California to see Michael Wittner’s BlueSky Biochar burn at the Simi Community Garden. Michael also used a cone kiln, and as he did the burn he narrated the physics of the process and described how the cone shape created an oxygen-free zone at the base. He demonstrated a layering technique that kept enlarging the zero-O2 zone until he was getting a smooth torus of flame with no appreciable smoke.

Some partially charred pieces reveal the source fuel
Two weeks ago, Kelpie described a test burn by Kamal Rashid, CEO at Zanjabil Gardens in Pembroke Township, Illinois, using a giant homemade cone kiln —  59" top diameter,  24" bottom diameter, and 24" high. The kiln made 133 gallons of biochar (17.7 cu ft) in about 4 hours, using cordwood. Kamal reports that it took 30 gallons of water to quench the kiln.

Some years back, with support of The Biochar Company's CEO Jeff Wallin, “Biochar Bob” Cirino went to Hawaii and made a video of another friend of ours, Josiah Hunt, who makes commercial biochar for the Hawaiian home market.  Biochar Bob is the spokesperson of CAFT: the Char Alliance for the First Tier. The First Tier represents organizations around the world that have working demonstrations and adoptable business models for using biochar in the developing world. Check out the Biochar Bob series on YouTube (Biochar Bob Goes to Haiti, Biochar Bob Goes to Costa Rica, Biochar Bob Goes to Brooklyn…).

In Josiah’s Hunt’s method, a shallow pit is dug in the earth, filled with woody biomass, ignited, and then covered to smolder. This is not much different than the method practiced by indigenous societies for at least the past 1000 years as related in The Biochar Solution.  It is pretty labor intensive and slow, but it yields a consistently large amount of biochar.

We wondered, before going to the expense of building a steel wok like they use in Japan or at BlueSky or Zanjabil (estimated about $400 in costs to fabricate), what if we build a pit like Josiah Hunt but shape it like a cone kiln and use the type of layering technique that Michael Wittner demonstrated?

That was our experiment, which we are calling Cone Pit method. We dug a cone-shaped pit — 54" top diameter, 24" bottom diameter, and 16" deep. The burn began with a single match and some cardboard boxes, along with a few small, very dry bamboo sticks. Within a few minutes it had grown to fill the bottom of the pit and we quickly started adding more and bigger bamboo to the fire. We watched for signs of it going white – indicating ash formation, and then we would throw on another layer of bamboo.

If we had more bamboo we could have probably made 10 times what we did, but we started with about 12 cubic feet of loosely piled dry bamboo and we used that in the course of the 12 minute burn. Then, with no more fuel, we started quenching at the edges and anywhere we saw white ash, and gradually worked the spray toward the center, ending the process after approximately 15 minutes. We quenched the fire thoroughly, left it out in the overnight rain, and then allowed it to drain into the ground for a full day before collecting and weighing what we had. It was 30 pounds dry weight.

The urine vat receives liquid from an ecohostel pissoir
From there the fresh biochar went to a urine bath. Even though it was quenched with water and was rained on during the night, biochar coming directly from a pyrolytic kiln will be hydrophobic – meaning it repels water. By soaking it in a vat of urine for some days or weeks before mixing it into our compost pile we can be certain to convert it from hydrophobic to hydrophilic. Now when it reaches the garden it will work like a sponge, soaking up water when it rains and releasing it back slowly to the plant roots as needed, along with all the minerals and nutrients being brought to the “reef” and stored there by the families of microbes.

It would have been better if we had found a good use for all the heat we generated in that 15 minutes — a good excuse for further experiments — but our fire was still relatively clean, producing nil carbon dioxide and keeping most of the plant carbon out of the atmosphere for the next 1000 years, hopefully time enough to change our renegade species’ wicked ways.

It may be, as Charles Eisenstein says, that the world is not going to be saved by international treaties or retooled economic initiatives that purchase megacorporate buy-ins, but by agricultural practices that regenerate the soil; restoration of forests and wetlands; smaller homes in higher density communities; economies of reuse, upcycling, and gift; bicycle culture; and home gardening.

Here is our short video:


1 comment:

turkeysong said...

Cool post. I'm doing a similar thing, but using a long trench instead of a cone shaped pit. The length saves a lot of effort, since wood doesn't have to be cut to fit.




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