Backyard Biochar

Warm Heart Biochar Troughs - Versatile and Efficient Biochar in Thailand

Kudos to the Warm Heart team for developing a series of trough-shaped Flame Carbonizers designed to work with a diverse array of feedstocks available to small farmers in Thailand and elsewhere. These kilns are similar to the pyramid shaped kilns except they are elongated into troughs in order to accommodate long stalks, branches and stems without the need for cutting. They are brilliant for bamboo!

Warm Heart has done a wonderful job of not only matching kiln design to feedstock, but also of creating and documenting the stoking techniques needed for efficient production with diverse feedstocks, especially light weight materials like rice straw that can ash very quickly if not properly fed to the kiln.

Warm Heart has also provided dimensions and welding details for constructing the kilns. That warms my Open Source heart!

Some pictures below, but make sure you visit the Warm Heart site for all the details: http://warmheartworldwide.org/new-type-fc-biochar-production-unit/

The Warm Heart Trough Flame Carbonizer

Stoking corn stalks

Stoking rice straw using the "drag method"

Wet blanket quenching method - very innovative!

Stoking bamboo in a longer, narrower kiln

Quenching bamboo biochar

Dimensions

Welding details

Flame Carbonizers for Biochar: In Practice and Theory

Here's a presentation I gave at the Char Production Gathering at Aprovecho in August. Tried to compile everything I have learned about Flame Cap Kilns and other simple carbonizers for making biochar.

Backyard Biochar in Cave Junction

We fired up two of the Oregon Kilns in a suburban setting in Cave Junction last Saturday - real Backyard Biochar! Had lots of help so it was a smooth run. We ran out of feedstock, or we could have made a lot more biochar. Here's a video:

Checklist for a Biochar Burn

Here's a checklist of things you need to consider when planning a biochar burn:

• You need a water source, first of all, both for safety and for quenching the char. 
• Several shovels and rakes for spreading and cooling the char when it's done.
• Old steel roofing material is helpful for spreading and cooling the char without getting dirt or other contamination.
• Dry wood. A moisture meter is helpful. It's not very efficient to use wood that is more than 20% moisture. 
• Safety - Helpers should all have leather gloves and wear cotton or wool clothing that won't melt. These piles can put out a lot of heat! It is good for at least one person to have a fire helmet and a face shield. 
• You may need to get a burn permit from the local officials. 
• Ignition - I use a propane weed burner type torch for ignition, but all you need is a match if you have plenty of dry kindling. Light it on the top. 
• Make sure the kindling is somewhat densely packed so it will sustain a flame and allow the flame to move down to the lower layers. It seems slow to start but pretty soon you'll find the whole pile is ablaze. 
• Use a wind screen if conditions are breezy. Even if wind is not a factor, a wind screen will help hold in heat for a safer and more efficient biochar burn.

Biochar at Daisy Hill Farm

Daisy Hill Farm owner Meadow Martell was happy that we made a big dent in a multi-year accumulation of old grape vines, blackberries and other woody waste. Meadow covered the piles back in the fall with used truck tarps from Sharp's Tarps in Grants Pass (a great resource, people!). As a result, the wood was stayed dry - mostly between 15% and 25% moisture and was suitable for biochar production. A small crew of neighbors showed up to help and share in the biochar bounty. Meadow will use the biochar in compost and in the chicken yard.

It was a misty morning down by the Illinois River (Cave Junction, Oregon)

We load the two kilns full with loose packed grapevines and light the top

Once the initial charge burns down to glowing coals, we add more, in layers

We lit these at 9:30 in the morning. by 1:00 pm we have added the last layer

At 2 pm the last layer has burned down and we are ready to quench

Meadow hoses down the char

Total harvest is more than 2 cubic yards of biochar

Work in Progress: Design Guide for Flame Cap Kilns

Flame Cap Kilns come in many different shapes and sizes. They all seem to work quite well, but there are some fine points of design that will help users determine the most appropriate configuration. Parameters to consider include feedstock type, available materials and cost. Keep in mind that large round cone shapes can be more expensive to fabricate in small welding shops than pyramid or trench shapes. On the other hand small cone shapes may be easier in some cases. Tubes can often be found ready-made. Look for other ready-made containers like small dumpsters or old tanks. You also need to consider how you will quench and unload your char. More on that later.

This Flame Cap Kiln Design Guide is a work in progress, but I want to share it now because I am getting busy with other projects and I don't know when I'll be able to get back to this to make it more complete. You can download the Flame Cap Kiln design guide, or just take a look here: 

 

UBET Kiln Designs

I am working with a group of innovators in Oregon called the Umpqua Biochar Education Team. They have come up with some super simple, very productive biochar kilns. The first one is called the "Ring of Fire" - it is a Flame Cap Kiln made with old roofing steel. As you can see, it can handle some large slash type of material. UBET member Don Morrison provided these pictures of his operation using forest slash material. It's probably the cheapest, most efficient small-scale biochar production tech I have seen yet. To make it work, you need to be able to seal the bottom of the kiln, and you need plenty of water for quenching. We are not using these kilns in a forest setting, mainly because it is too hard to seal the bottoms on rough ground. Here are the pictures:

More pictures here:

https://picasaweb.google.com/113563255252052826854/DonMorrison?authuser=0&feat=directlink

 

New Flame Cap Kiln Design from Hans Erkin

I really like this kind of approach using low cost materials. No need to spend a lot of money for backyard biochar! Very innovative!

Making Biochar in the Snow

Making biochar in the snow. This Flame Cap Kiln is 14 ga (1.9mm) steel and it weighs less than 200 lbs. It's an inverted, truncated pyramid with a bottom base of 122 cm (4 ft), a top base of 152 cm (6 ft) and sides 66 cm (26") high. Capacity is 1.2 cubic meters. Cost $600 to make in Oregon, USA.

Oregon Kiln Making Biochar in the Woods

Well I finally did it. Got some kilns out in the woods to burn slash piles that are normally incinerated to ash. Thanks to Grayback Forestry and Sean Hendrix for inviting us to bring the kilns to see what they could do. Each kiln consumed about 6-8 burn piles and made close to a cubic yard of char. It rained steadily all morning, but we were still able to make char. We lit up at 9 am and quenched at 12:30. I was pleased to see it took less than 50 gallons of water to completely quench one kiln. Took a lunch break and dumped the kilns and loaded them back on the trailer. Went pretty smooth, really.

Some of the Forest Service fire people were there and they said that 7 piles corresponds to about 40 feet of roadside thinning. So if you could unload 20 kilns along 800 feet of roadside, you could treat all the slash and make 20 cubic yards of biochar in 6 hours of work. If the feedstock is well-staged and you don't have to pull apart piles and move it long distances, I think one worker (a young, strong one, not me!) could feed 4 kilns continuously. So a crew of 6 could do it. You'd need a flatbed to transport the kilns and 1000 gal water truck to quench.

The only part I have not figured out yet is how to gather up the biochar for bagging. I'd like to try a shredder vacuum, but I worry about wet char sludge clogging up the works. Otherwise, a loader with a scoop could pack it into totes for sale. You'd get a little forest duff in the bags, but that's a bonus extra!

 

Web album here: https://picasaweb.google.com/113563255252052826854/OregonKilnSlashPiles?authuser=0&feat=directlink