Jock Gill


Jock Gill has been demonstrating Pyro-grilling. He adapted a standard weber to use an updated version of his iCan stove. He reports that he hasn't had to buy standard charcoal in over a year. In the process he has been making a nice grade of biochar.

It looks pretty tempting. For details and answers to questions about the grill please download Jock's Pyro-Grilling pdf .

Grass Tablet Biochar
Grass Tablets
Grill modified with an iCan reactor

The grass tablet biochar (pyrolytic carbon) shown above was made in an iCan TLUD
with a variable speed blower. This charcoal was air quenched and is thus bone dry.
When wet, it is very soft and can be formed to fit a variety of shapes. I have found, for
example, that grass tablet biochar saturated with cold water is effective at reducing the
pain of burns.

The following pages illustrate some of the ways the above biochar was made.
Note: Grass biochar will be ashy as grass has considerably more ash content that

Grass tablets broken into short sections prior to being loaded into the fuel chamber of
the iCan reactor.
These tablets were made from field grass about 3 years ago in Shelburne, VT. Note
that the longest fibers are about the length of the diameter of the tablet. Shorter is
These tablets are about 4 cm in diameter.

Download the attached Grass Tablet Biochar How To for detailed Reactor photographs and answers to questions posed to Jock by the stoves community.

Pot in the flue as was done in the Swiss Volcano Stove.
Detail of the deflectors above the secondary air ports.
 Detail of secondary air port.

I revisited an earlier secondary air concept that used 3 triangular ports at 120 degrees around the fuel can. Importantly, the the third side of the triangle was bent down into the fuel can to create a vane to increase turbulence.

What I did today was to add three deflectors above the secondary airports/vanes. The deflectors were positioned midway between the ports and just below the top of the fuel can. Thus when the draft can was added, there was effectively no secondary air gap at all.

While this is only one run to see if the would work, the results were very good. Lots of turbulence. Some good flame noise. At the 15 minute mark I put on a 19 oz can of very cold tap water to boil. It boiled in 15 minutes. After about 30 minutes over the flames and in the flue, there was only a small amount of soot on the "pot". The pot bottom was NOT black. Ambient air temp was about 45f. Little to no wind.

A few pictures:

Student set up using two 15 oz cans and a larger outer can for safety and to protect the fire from wind gusts.
Outer can removed. The secondary air gap is about 1.2 cm
This shows the three 3 cm washers used to create draft deflection back into the mixing chamber in the top half of the bottom can.
Botom can as it will be used.
4 lbs tuna fish can used as the feedstock can, or the bottom can, standing on its three small angle brackets. The primary air gap is about 2 cm
The simple draft can, both ends removed, is supporting the Feedstock can for this photo.
Smaller cans are being used inside this larger grill

Below are a few photos of a novel, at least to me, use of draft deflectors in
combination with a secondary air gap and a mixing chamber above the feedstock,
but below the secondary air gap.

This design is typically yielding abut 22% of the feedstock's weight as biochar.
Passes all of the usual simple tests. Run times in the larger tuna fish cans are in the
42 minute range with 500 grams of soft wood pellet feedstock. I load the bottom
can, of the feedstock chamber, to only about 50% of capacity. This leaves the top
half of the can as a mixing chamber into which the draft is deflected. This creates
thorough mixing of the combustible gases with the secondary air. The result is very
clean stack gas. I wish the many small diesels out there burned nearly as cleanly.


Jock Gill, Vermont, 2011

Jock's new TLUD Design. It has a passing similarity to Lanny Henson's Sidewinder, but instead of 4 symettrical slits, to provide the 'vortex' at the heart of the cooker. The iCan D uses only three secondary air apertures for maximum turbulence and asymmetry. It also uses a more triangular cut arranged such that the resulting tab is at 45 degrees and can, when folded into the can, act as both a vortex generator and a concentrator.

Currently I have only tested the mid-sized coffee can unit with 142 grams of fuel. This gives me a runtime of about 27 minutes -- start to flame out. It has yielded 21.8%% biochar as a percent of weight of fuel -- soft wood pellets.

It gets good results when loaded with 25% of the capacity of the can - in this case about 142 grams of wood pellets. Run time: 27 minutes. Smoke gone in well under two minutes. Biochar was very clean, 100% charred fuel with no floaters in a water quench. Minimal ash. Biochar harvest was 21.8% of the weight of the starting fuel load. Only minimal soot in the stack gases for about 3 minutes at the peak period.

Jock Gill, April 2011
Peacham, Vermont, usa

For more about making the iCan stoves see: The Peacham iCan TLUD instructions on the Stove site

My little iCan made from a 3 lbs Costco coffee can boiled 1.75 liters of water in 42 minutes this afternoon. Ambient temp was 47 [8.33C]. This was done in 5 batches averaging 350 ml each. A very clean burn. Some soot at the start of each batch when the water was cold. Just a soon as the water in the cup warmed up a bit, the soot stopped.

Of course I also made some biochar as well.

Fuel was a good quality wood pellet. Cost of fuel: about 17 cents assuming pellets at $230 per ton. They can be bought for a good deal less, but I am using a higher number to be safe.

Cost per liter boiled: ~ 7.4 cents, allowing 4 cents as the value of the biochar captured at the rate of 17.5% of the dry weight of the fuel.

See the all new 2012 instructions attached:

Jock Gill, It's Summer!

See the attached pdf file for printable Char-B-Que Instructions in Gorgeous Full Color Detail!

Jock Gill, Northeast Biochar Assn, April, 2010

Vermont Public Radio Coverage

A new biochar story in Seven Days, a Vermont newspaper:
Shelburne Farms Experiments with "Biochar" to Clean Water and Revitalize Soil

Television coverage of Biochar Demonstration at Shelbourne Farms, Vermont


Jock Gill, January 2010

Grass Biochar made from a mulch hay tablet, and also from a crushed hay tablet.

See how the structure survives in the uncrushed tablet.

 These two posts may be of interest.  In any case, all comments and suggestions are welcomed.

1. A Path Towards Carbon Negative Heating


2. A Path Towards Low Carbon Agriculture

The second link lists 5 possible policy options, with a 6th in the comments, that might be considered. Note: none mentions biochar, but agreement with more than a few pretty much eliminates all but Biochar.  The idea is not to pick winners and losers, nor to tell elected officials what they have to do, and not to give policy staff one word they do not understand but gives them an excuse to walk away from the entire idea.




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