you can put it in soil.
January 20, 2009, with Nate Darrow of Saratoga Apple and Tim Holmes of Regional Farm & Food Project (RFFP), I went to visit Cornelius near Pawling, New York, an hour north of New York City, to see his new biochar burner.
In South Africa, Cornelius developed small-scale industrial pyrolysis equipment to produce charcoal for the gold mining industry. His equipment was designed to process peach pits—an agricultural waste that's very high density feedstock—into activated carbon for industrial filtration in gold refining. A few years later, in tropical Mexico, Cornelius worked with farmer cooperatives to process coconut shells—another high-density farm waste—into activated carbon. With patent royalties from his equipment designs, he happily operates Rainbow's End Butterfly Farm in southeast Hudson Valley.
Two years ago, Cornelius met Doug Clayton, who introduced Cornelius to using charcoal in soil—a new idea in his long career of char-making. Cornelius had one of his char-making units shipped to his butterfly farm in the US, and began to think and tinker to modify the burner to process woodchips.
Cornelius' equipment operates in continuous feed mode, rather than the much simpler batch mode. Woodchips are more challenging to handle than pellets, in part because their diversty of sizes, irregular shapes, and sharp, ragged edges make chips stick, clump and clog. Compressed wood pellets—round, smooth, uniform size—have far better flow characteristics than ragged, irregular wood chips.
Cornelius has greenhouses to grow special food plants to feed his caterpillars and butterflies, so he wants to design a biochar burner scaled to heat for his greenhouses. Cornelius' industrial-scale equipment proved to be too large and heavy to work with, especially for a unit scaled to heat two greenhouses. So, he scaled down his 6-foot diameter burner to a 55-gallon barrel, and redesigned his apparatus to automatically deliver feedstock to the burn chamber. Cornelius also added a water-jacketed heat exchanger to convert process heat into hot water to use for space heat and thermal storage.
The triangle box on top delivers measured units of feedstock to the burner, which is inside the round barrel below. This burner operates much like aTLUD, with certain sophistications. Several damper-style airports around the lower end of this barrel regulate air flow into the burn chamber. I didn't study the operation closely or ask questions, but I assume periodically a gate opens, and a measured amount of feedstock drops into the top of the retort. Feedstock moves down through the retort by gravity, heating as it descends, eventually gasifying, then carbonizing, to exit out the bottom, ejected at intervals by a gated portal into a half-barrel underneath. Each dump of char is sprayed with water to stop oxidation to ash and prevent flare-ups.
I didn't have opportunity to study Cornelius' heat exchanger, but a steady half-inch stream of steaming hot water squirted into a blue barrel on the left—adequate to run through buried pipes to heat soil under a greenhouse bed. And while I didn't do any hard number calculations, i was impressed how much heat is generated by this 55-gallon burner & retort. Perhaps this scale unit can heat a small production greenhouse; I had assumed a larger burner is needed, but I hadn't considered a continuous feed unit operating 24/7.
So, it seems Cornelius hasn't just created a burner, but an entire multi-function machine capable of automatic operation with minimum management. Cornelius is experienced at the design & invention process, and is thinking ahead to refine this intial "proof-of-concept" into a working prototype, which can be tested and perfected into a machine reliable enough to manufature and market as a replacement for propane, biomass and bio-oil burners currently in use.
My special delight was watching Cornelius describe charcoal's effects on soil, and growth of his butterfly feeding plants. He understands thoroughly that char isn't a fertilizer or food source. Rather, biochar is a substrate that is inhabited by micro-organisms. Thus, it's imperative to "impregnate" the char with a diversity of microbes and other soil life. His eyes light up talking about microbes, and he radiates an infectious enthusiasm.
Cornelius went to Oregon to study with Dr. Elaine Ingham about the Soil Food Web. He is very enthused about compost tea as a universal soil treatment to inoculate and jumpstart the soil biology. He bought a $1000 microscope and digital interface to record videos of micro-organisms in his compost teas. We watched a few micro-videos of rotifers, nematodes and micro-fauna—amazing how fast those critters dart about!
Cornelius is focused on Rainbow's End Butterfly Farm (open to public mid-May), and has significant time and money invested to develop his biochar machine. Yet, Cornelius wants to collaborate with scientific research on using biochar in soil. And he also wants to host workshops or a conference at Rainbow's End Butterfly Farm to showcase his invention and spread the word about the critical value of biochar for environmental restoration. He holds education programs with schools on the farm, with facilities for meetings. We are discussing a small, modest biochar workshop at Rainbow's End in ealy May, and larger event in late summer or early fall.