I am always flattered and excited when asked to do product reviews related to biochar. Recently Bruce F. designed the CharCone, a mini Kon-Tiki geared towards the cooking crowd and asked if I’d be interested in taking it out for a test drive.
Bruce comes to the biochar world from a unique perspective. A former chef and now a small business owner of SpitJack, he definitely knows his way around fire. He also managed the sumptuous banquet at the US Biochar conference in Amherst which included some very unique biochar elements. Bruce is very collaborative which isn’t overly common in the commercial world of biochar, so of course I agreed to test his kiln!
The first burn I did was on a day which was too windy so I aborted before getting too close to the edge of the kiln. Even so, about 5 gallons of char came out very nicely with only a few larger pieces that didn’t char through thoroughly (those just go in the next burn). One trick with a small kiln is using easily bendable feedstock (e.g. dried reeds) to get a bed of coals going. This kind of fast burning feedstock is also good to use for the last 10 minutes or so of a burn as it keeps the fire going but doesn’t need a lot of time to fully char.
The second burn was on a perfect day wind-wise but a bit on the hot side! Here are a few thoughts on using different feedstocks with the CharCone:
- Honeysuckle – this invasive shrub is a bit unwieldy but charring it is the best way to minimize its spread. It is best to let it dry out for at least a few weeks, but even then it can take some care to safely use it. It bends easily enough and burns great, but it unbends in the fire and often hangs over the side of the kiln, so it’s best to keep an eye on it at all times.
- Old fence wood – burned fast. If you use this sort of thing, make sure it is untreated wood so no nasty stuff gets airborne or into your soil.
- Sawdust – a great starter feedstock as it makes an ember bed quickly; also good to use at the end to finish off the burn. Make sure you don’t smother the flame though. You may want to use a poker to move the sawdust around if it is clumpy as the sawdust might not fully burn otherwise.
- Densified ethanol waste – Not something most people will have access too, but a local company asked me to make some char from this awhile back and I had some leftover. This is a somewhat sticky, chunky feedstock which burns hot and for a relatively long time. Seems to have completely charred through probably because I put it in about mid-burn.
- Bones are a great source of renewable phosphorous or phosphates and calcium. They take a while to burn so add them in early and make sure they don’t get covered over too quickly so they can char thoroughly. If you are making char for soil use, add as many bones as you can find!
- Lobster shells – thanks to a lavish Christmas dinner I have 2 buckets full of smelly lobster shells (even 5 months later they still smell!). Lobster shells are also a good source of renewable calcium and a little something called chitin – a nitrogen rich polymer which has found use in everything from biomedicines to agriculture to golf balls. [Fun fact: the world generates 6 – 8 M tons of crab, shell and lobster waste every year with most of it going to waste!] A biochar researcher friend of mine recently purchased chitin, which can be fairly expensive, to mix with his char. Charring your own lobster shells is completely free and you get to enjoy a delicious lobster meal beforehand too! (Other research on pyrolyzing chitin shows it has promise as an electro catalyst with similar properties as platinum.) These shells burn pretty quickly so they can be tossed on to the fire at almost any point.
A full burn took 1:45 and generates more than 10 gallons of what looks to be very good biochar. Quenching the burn takes less than 5 gallons of water which is very handy. The timing of feeding the fire is entirely dependent on what feedstock you are using. If you are planning to cook, it would be better to use larger sticks so you don’t need to feed the fire so often.
What I really like about this kiln is its transportability. With a few tools the legs can easily be taken off at which point the kiln fits nicely into the back of a car. This makes it ideal for taking the CharCone to educational events or over to a friend’s house to help them char through yard debris while cooking a few hot dogs. With this kind of kiln you could also create a local Uber or CharB&Q for Kilns, which I believe Bruce has set up in Easthampton, MA. For more information on purchasing or renting kilns, check out the CharCone website.
Overall I highly recommend the CharCone!