Durable Biochar Producing TLUD Camp Stove




Introduction: Durable Biochar Producing TLUD Camp Stove

About: Forty years of real world applications of biomass energy, food, feed, and fuel, in the Missouri Ozarks.

TLUD - Top Lit Up Draft stoves are an innovative technology for high efficiency, low emission conversion of woody biomass to biochar with plenty of useful heat available during the process for cooking and heating water.

Design and use of TLUD's is counter-intuitive to say the least.  
  --Rather than lighting a match to the bottom of the pile, the pile must be started on top.  
  --If the process is smoky, you REDUCE the process air going into the pile.

Proficiency in getting them started and adding fuel takes some experience.  But in terms of efficient conversion of biomass to useful products their performance is at or very near the top among the latest world stove designs.  

They offer a highly carbon negative footprint.  Because they can be tuned to work with many locally obtainable biomass residues, there is no need to transport or store expensive fossil fuels.  The co-product of the heat is biochar, a new-old technology that enhances crops while interring carbon in the soil long-term.

Enough banter, lets get to it.

Although tincanium and obtainium are practical when testing designs, stainless vessels offer better radiant heat properties and long term durability.

This design begins with a 2 liter vacuum insulated serving pitcher.  Depending upon the number of holes and fuel quality (drier and denser is better), it finishes with a stove that boils a quart of water in 10 minutes and keeps it boiling for half an hour on a half load - one pound - of hardwood pellets.

Step 1: Remove the Bottom Cover.

Starting with a standard stainless serving pitcher, using a chisel and hammer, place the chisel in the crease near the bottom. Rap the chisel with the hammer to make the base slide down clear of the main vessel.

Keep moving around the diameter, take it a little at a time, until the base releases completely from the vessel.

The same procedure works for removing the top cap.

Step 2: Bare Vessel

Hammer and chisel make quick work of stripping vessel down to just what is needed.

Step 3: Punch Inside Process Air Holes.

A long, sharp pointed screw, with a pancake head, makes an ideal punch.  Sharp is the key.  Stainless is tough.

Process air holes are punched from inside and outside.  Process air feeds up into the center bottom of the biomass pile.  Natural draft, like a chimney, pulls air up through the pile as the process gets going.

I offset the inside from outside holes to prevent the odd hot char from dropping out the bottom of the vessel.

More holes, more power.  Less holes, longer run-time.

What is ideal depends upon power needed and on-site fuel.

This stainless vessel is among the most tolerant I have ever used for various fuel types.

Step 4: Punch Outside Process Air Holes.

Match the number, but do not match the pattern of the inside holes to help prevent char dropping from vessel.

Step 5: Punch Combustion Air Holes in Base

Combustion occurs at the top of this vessel when a second round of oxygen hits gases that have been "boiled off" the pile of biomass using process air for thermal decomposition.

The outer ring of holes are the combustion air that flows from the holes in the base, up between the stainless steel skins.  It is pre-heated before being introduced inside the vessel at the top.  Pre-heat is a very important concept.

Roughly twice the number of holes, a 2:1 ratio of combustion to process air seems to work well in this vessel for most fuels I have tried.

The end result can be a beautiful flame pattern when a cooktop and pot are in place to "cap" the process.

Step 6: Make Top Holes

For making the top holes, a punch works.  But a drill works better.

Step 7: Accessories

By sealing outside air out of the outside upper holes with a suitably sized tin can similar to the pictured chimney pipe, a basic TLUD is finished.  

To use it, fill the vessel 2/3 to 3/4 full with a dry, woody biomass fuel, check that airflow is unrestricted from the bottom, and light it from the top.  The most flammable pieces should be on the top of the pile for easy starting.  An accelerant like lighter fluid does wonders for a quick clean start.

TLUD's cannot be made much simpler or efficiently in terms of labor input versus durability and raw material costs.  I can make a half-dozen in the time it took me to do this instruct able.  

If time is not an issue, they are simple to make from clay for an even lower material cost.

Testing hole sizes and shapes with various tin-can "chimneys" is a great learning tool and time sink.

For my own real world use, I add a couple of simple accessories.

A one gallon paint can with the bottom center cut out, and a short piece of pipe for a chimney/duct attachment adds great utility to the basic unit.

Step 8: Insert Vessel Into Paint Can

Apply insulation inside the paint can first if desired.

This particular vessel slides into a secure, snug fit on the paint can original opening.

Then slide the chimney down from the top.

I like to add a few small holes near the point where the chimney clears the paint can to introduce a final bit of combustion air.  It generally promotes a cleaner burn as the process gets rolling.

Step 9: Ready to Run

Finished enough to suit me.

The paint can handle allows it to easily be hung on a standard T-post at preferred working height.

Step 10: Cooking Accessory Attachments

A 4" OD chimney allows using off-the-shelf sheet metal duct fittings. like the 4x7 reducer pictured here.

Slipping a water pot down into a shrouded enclosure dramatically improves water boiling performance.

Step 11: Burn, Baby, Burn

Step 12: Snuff When Flame Dies

It is possible to let the char burn for longer operating time.  Carbon monoxide levels go way up (from extraordinarily low levels) in char burning mode.

For less carbon in the air, and more in the ground AKA "biochar", cap all holes when the flame disappears.  On a full load of hardwood pellets, you still get several hours of gentle heat before all outer surfaces are cool to the touch.

When outside surfaces are cool, unsnuff and pour out a beautiful, light, biochar co-product that was produced IN ADDITION TO USEFUL HEAT

Char has been used for art, medicine, filtration and fuel since the earliest days of civilization.

Step 13: Build or Buy

Build or buy, what is time worth?

Artisan tooled finished product available online at The Power Mall.

Purchase there helps fund my efforts to increase the knowledge base and use of safe, cheap, obtainable, renewable biomass energy.  For long term energy security, nothing else comes close.

Perception, not reality, holds back biomass - the Rodney Dangerfield of alt energy.  When biomass finally gets used correctly, and garners the respect it deserves, it will change the world.

Step 14: Foundational Technology - DrTLUD and TouCan

Works by Dr. Paul Anderson, DrTLUD, one of the top biomass stove practitioners on earth, and Dr. Hugh McLaughlin, possibly the top biochar characterization authority on earth, inspired the design of the KeyStove LX.

The picture is from page 7 of "TLUD and TCHARBON Stoves for Sustainable Haitian Development" by Dr. Anderson and Christa Roth, full text available on Slideshare

Hugh McLaughlin, Alterna Biocarbon, provides more operational details than anybody cares to know in this "TouCan" pdf document hosted at bioenergylists.org  

Step 15: KeyStove LX Heat Extender Adapter

A simple adapter to dramatically increase total heat output per biomass input.  

It allows using the char just created for fuel, rather than saving it for later soil enhancement or liquids filtration.

Just slip it in the chimney when the yellow flames die down.  Runtime heat output is much lower, but the heat continues for a VERY long time.  

Twelve hours runtime from this configuration, and the char from a pound of pellets was only half consumed.

NEVER BURN CHARCOAL INDOORS!!  Look at the warning label on a bag of charcoal for details.

Any can that fits down the chimney (ho ho ho) with holes punched in the old bottom-new top reduces air flow without extinguishing the char burn.  Experience allows fine tuning the hole configuration and stack height to the fuel and desired runtime.  Char would seem to be a standard fuel, but spacing and density varies by initial feedstock choice. 

Pictures in order show:
  1. Installed
  2. CO warning
  3. Bare attachment.

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    8 years ago on Introduction

    compliments a very interesting project, thanks! I'm thinking for some time how to make a version of biochar stove for inside, I would like to use it in a tent, in particular a ger housing typical of the Mongolian population.


    Reply 8 years ago on Introduction

    There is a lot of work by a lot of groups that has taken place in Mongolia. There is a research paper with conclusions dated 2005 from that region.

    Efforts continue on at least a few fronts. I would love to help, have been approached, currently caught in the time-money continuum, lacking both ;~)

    I suspect as with mobile touch screen tech, the breakthrough will be with the right mix of ease of use, practicality, and "looky here" pride of ownership.

    Certainly wish the good people of Mongolia and those who would help them the best.



    9 years ago on Introduction

    THANKS ! We need more of this kind of information. Very well done, indeed !


    Reply 9 years ago on Introduction

    Thank you for the kind worlds.

    We need more of these stoves out there. They really open eyes to the power in biomass energy.


    9 years ago on Introduction

    Nice Project, I am looking to make one for a Sailboat and use it
    to Dispose of waste aboard. Also would like to add a heat exchanger
    for Heating Potable Water. through a Loop. Will be an interesting project
    to Hang over the side on a Marine BBQ style bracket.
    P.S. Will be making up a prototype out of "Tincanium" added a new
    word to my vocabulary. Cheers


    Reply 9 years ago on Introduction


    Char produced is excellent for odor control of many waste products. Heat works for distilling water and other essentials.

    Keep on playin and keep on charrin'


    9 years ago on Introduction

    Excellent! I've been trying to find a way to cheaply produce this biochar stuff I keep reading about, and this seems to be just what I was looking for!

    A couple of questions I would like answered, if at all possible. I'm still new to this, so if these are questions that are fairly obvious, I do apologize.

    1. What gases are given off during this process? Are they just like normal flames, like CO2, CO, and CH4, or is something else entirely cause all the carbon is being sequestered? Can this gas, if different, be captured and used in any other processes?

    2. How much heat does this produce? Could I, say, bend some copper tubing into a coil, put water through it, and put it directly above the flames to more quickly heat the water, or is that not at all feasible?

    3. Should this only be used outdoors due to potentially toxic gases, or is it safe to use inside of ones home?

    4. You may have addressed this and I simply missed it whilst reading, but about how long does this process take to produce the biochar? I understand that the burn isn't as hot at a normal fire, so does that make it a slower process? Could I feasibly change the fuel into biochar and put it in a garden in one day, or should I do most of the production a couple weeks or months before?

    Thank you so much for your time and this wonderful information! I'll be sure to tell my friends and family about this!


    Reply 9 years ago on Introduction

    1. The old woodgas.com site had some really good info on makeup of biomass and products of combustion as pyrolysis takes place in a vessel. Simple in a graph once you understand it, way too detailed to cover here.

    2. Approximately 7500 btu until somebody says different with supporting docs. Heat may be focused or diffused with various chimney attachments. Gas can be directed but in so doing can easily turn everything in path into a tarry mess.


    4. Biochar co-product is left behind when flame dies. Essentially the volatiles have been flared off the biomass leaving the hard char. From there snuff and allow to cool. Other options available with more study and experience.


    Reply 9 years ago on Introduction

    Thanks and right you are!

    Added a page for foundational technologies.