Making Charcoal/Biochar

This morning, (April 28, 2019) I converted a 55 gallon barrel of dead limbs and tree trimmings into charcoal.  According to my Logbook, it is barrel #330.  This charcoal making process started on June 8, 2012 when Martin Payne who is a member of a Woodgas online forum showed up in my yard with a couple of drums and said we are going to learn to make Charcoal.  Over the past seven years, I have modified the process and actually learned the ART of making charcoal without making any smoke in the process.  Our/my Teacher, Gary Gilmore, works for the Forestry Department in Pennsylvania and besides contributing to the Forum, also made a series of very good YouTube videos on how to make charcoal using a two-barrel TLUD system.  Search YouTube for "gary gilmore charcoal".  Here is a direct link to his charcoal making set-up:  https://youtu.be/2xsHsWP-E9k
This was seven years ago, and started me on the journey.  Now I will describe the system I am currently using.  (Think Evolution.)
Find a good open top 55 gallon drum and punch or drill 5/8" holes 2" up from the bottom on the side of the barrel.  Put them 8" apart.  I like to start the holes with a small drill, and finish them off with a 5/8" round chisel.  To remove the top of the barrel use either an angle grinder with a cut-off wheel, or use a chisel, or a combination of the two. The next step is to create metal liners for the barrel from scrap roofing panels or the like.  It will look somewhat like this:

A quick and easy method to cut a slit in tin is to lay down a 4 X 4 and strike alongside it with an old hatchet.  Another method is to wear thick gloves and use tin snips.  Works of art are not required, as these sheet burn up after several months of use.
Now, fill the barrel with junk wood.  It is better if all the wood is nearly the same size.  Here is a load of the "Big Stuff".  (This barrel was before I started using the liners, but it shows how to really load a barrel with the thicker stuff on top.)

To ignite this, I use rolled up paper, sticks, tree trimmings, and kindling.  Stick as much kindling as possible into the gaps in the wood, and then put a second barrel over the top of this one.

If you are not using the liners, then place two rods of 1/2" rebar across the rim of the lower barrel to allow air to enter.  With the liners, just set the second barrel on top of the lower barrel of wood.  I use crumpled-up paper balls made from junk mail or newspaper to ignite the kindling.  Once it is going, feed branches and twigs into the top of the two barrel setup to keep the very hot fire on top.  I also use little logs made from old telephone books, or old damaged paperback books to keep the fire going on top of the load.  This is the key to a no-smoke burn!  I have dozens of feed sacks stuffed with paper balls and paper logs.  (Make them while watching the newless News on the Tele.) Use compound loping shears to cut armloads of tree trimmings that you can continuously toss into the top.  The idea is to create a strong bed of coals on top of this wood that will work its way down to those airholes you punched in the bottom of the lower barrel.  Keep a watch on those air holes, and when you see glowing charcoal through a hole, cover that hole with clay, dirt or sand.  Eventually, cover all the holes up to the first ring on the barrel.  Remove the top barrel with gloves and a pair of heavy duty pliers, and set it to the side.  (Don't knock it off, because it is very hot and soft and will distort to an oblong shape and won't fit the round barrel for the next session.

After about 2 hours, the pile of wood will have collapsed into a pile of very hot coals in the bottom half of the barrel.  If there are visible orange flames, it still has raw wood that has not been converted to charcoal.  If it is just one large piece, it will have to be finished off another time.  Wood pieces as large as in the photo might take 3 hours, maximum.  A barrel of small limbs and driftwood might be done in 1.5 hours. 
Pour 20 gallons of water onto the charcoal.  The holes are covered with clay or dirt, so the water will stay in the barrel (with the exception of the steam) until the fire is completely out.
Usually the next day, remove the dirt with a shovel or hoe, and tip the contents of the barrel onto some tin or a large piece of old plywood.  Don't worry about the water, because it always seems to find a way out of the dirt around the base of the barrel.

Spread the charcoal out with a rake, and pick out any large pieces to save for your wood stove, or to throw into the barrel in a future batch.
Next, screen the wood.  I use a shaker box covered with 1/4" hardware cloth over another screen of 1/8" hardware cloth.  Pick out any brands (unfinished pieces of wood that were not converted to charcoal) and nails, screws, rocks, etc.  Ashes and charcoal fines will fall through the 1/8" cloth,

 and on top of the cloth will be small pieces of char that are less than 1/4" and greater than 1/8".  Collect this and store it separately.  Mix the fines shown in the wheelbarrow into the compost pile and let it sit for a while.  Alternatively, put it in a bucket, and use a large can to scatter it downwind over the pasture. 
The larger stuff above the 1/4" hardware cloth will now go to the charcoal grinder, which is merely a copy of the one Gary Gilmore built.  https://www.youtube.com/watch?v=37-h41iT68M
The one Gary built is shown here, and then the one I built using recycled materials:

It is cranked by hand.  A 3" diameter pipe with pieces of railroad spikes smashes charcoal through a "comb" of other railroad spikes.
After the charcoal is ground, put it back on the screening system and get rid of the fines, and checking for any brands, nails, etc, and then store it in a sealed container for use as engine grade charcoal that can be used to run an internal combustion motor.
At one time, it was possible to purchase charcoal fines from a BBQ packaging plant in large bags.  (They no longer sell it.)  The charcoal sold for BBQ is not suitable for running internal combustion engines because it is not completely converted to charcoal.  The smoke adds flavor to the meat.  Toward the end of a charcoal making process with the two barrels, a few coffee cans of this "unfinished" charcoal can be added.  Here are two methods of hauling home these 900 pound bags of charcoal.  This is a 2013 Tesla Model S85.

 Here is the old 1990 Dodge.

My tractor front-end loader would not lift 900#, so the charcoal was transferred to feed sacks using 5 gallon plastic buckets, until the loader was able to lift the partially full bag.
May 11, 2019  My system of making charcoal has a hard time handling woodchips, so I usually add them to the compost pile.  Another modified two barrel (actually 3 barrels) method seems to handle the woodchips, as pointed out in this YouTube Video by Marty Kraft.  https://youtu.be/2zSiQGzgfmo

June 1, 2019  A neighbor gave me a load of old pine lumber (in really bad condition) that came from a house that was demolished.  This house was located very near the old Lytton Springs High School built in the 1880's.  I used this wood to make 5 barrels of charcoal and charcoal fines which I have spread out on the front pasture.  I have previously spread charcoal fines on a back pasture, and right now that pasture is extremely lush and the grass is very thick.  This could be due to one of the wettest months of May in history (in Austin), or to the charcoal fines, or both.  (Probably the rain 🙌)  The front pasture has a very poor area, and I'm hoping the minerals and trace elements plus the charcoal fines will help it.

Update.  June 11, 2019  The same neighbor that gave me the pine lumber offered me several truckloads of logs and tree limbs cleared from his pasture.  At noon today, I brought this load home.