Science: Energy: Bioenergy: Waste
Charcoal pellets from agricultural residues   (+12, -1)  [vote for, against]
They look a bit like goat poo

Many people in developing countries use charcoal or fuel wood to cook and heat.

However, this leads to deforestation.

In most of these countries, people burn agricultural residues from their fields - like straw -, on their fields (to get rid of pests, etc...). They don't use these residues to cook, because they cause thick smoke.

If there was a way to make charcoal of these residues, deforestation could be limited, and women & children wouldn't have to walk for hours to gather fuel wood or buy charcoal made from wood.

The problem isn't that you can't make charcoal from these residues, the problem is that it crumbles very easily to become dust and powder, making it difficult to transport this fuel or to throw it on a fire (the dust can even extinguish fire).

I have a simple method to change this.

I made a slide-show of it, because I have tried it myself, and it works!

1. make charcoal out of residue (sugarcane trash, straw, cassava twigs, rice, peanut hulls, etc...)

2. grind the charcoal until you get a powder (very easy, requires not too much effort - the fines crumble in your hand)

3. get some cassava starch; we will use this as a binder; cassava starch is very abundant in most developing countries

4. start cooking. Put charcoal dust in pot. Add some water. Heat it up. Add your cassava starch. Mix well.

5. now you have a thick, rubber-like black paste.

6. let it cool a bit, make saucages out of it, and cut them into pellets

7. let the pellets dry in the sun, upon which they become rock-hard, and you're ready!

Now you have charcoal pellets that burn very cleanly, that are hydrophobic and can be stored for a long time, that can be transported, and - best of all - that aren't made from wood, but from waste that otherwise would be burned on the field.

It might look a it labor intensive, but gathering fuel wood is so too. What's more, the charcoal pellets burn very cleanly and thus they would diminish the health problems related to indoor smoke pollution (a major "killer in the kitchen").

They would also cut deforestation dramatically.

I did a bit of an energy balance study, and the energy you put into making the pellets is low compared to what you keep after the effort. So the energy balance is 'positive'.

What do you think?

Next, I want to run a car on these pellets. A woodgas car. But that's another project... :-)

Check out the step-by-step (very much so) slideshow!

PS: I know, the pellets look a bit like fossilized goat poo, which is reason enough to like them!
-- django, Sep 18 2008

(?) Slideshow: charcoal pellets from waste http://s492.photobu...iochar/52a6834f.pbw
Easy and it works quite well! [django, Sep 18 2008]

Alternative link to slideshow http://s492.photobu...urrent=52a6834f.pbw
Hopefully this works? [django, Sep 18 2008]

Solar Tar Still Solar_20Tar_20Stills
Essentially the same idea. [bungston, Sep 18 2008]

Barrel in a barrel
Very easy charcoal making from trash - note: instead of using the heat resulting from the combustion of pyrolysis gas to barbecue, I use it to dry my wet biomass waste feedstock [django, Sep 18 2008, last modified Sep 19 2008]

Huge solar furnace for flash pyrolysis
In France [django, Sep 18 2008]

The most famous, even huger, solar-chemical reactor http://farm1.static...2268_6446d9e6fc.jpg
Odeillo, France [django, Sep 18 2008]

And the other French one - the Frenchies have something with this technology http://www.promes.c...mages/montlouis.jpg
Mont-Louis solar-chemical processor, Pyrénées [django, Sep 18 2008]

Solar furnace used as aluminium smelter http://www.kottke.o...s/solar-furnace.jpg
In Uzbekistan. [django, Sep 18 2008]

Home Solar Charcoal Distiller Home_20Solar_20Charcoal_20Distiller
Similar, but purely armchair. [bungston, Sep 19 2008]

Rumford's fiery balls http://www.rumford....neyfireplaces3.html
Indented section near the bottom. [spidermother, Sep 20 2008]

Slideshow: feedstock and charcoal making http://s492.photobu...urrent=8fbbd50a.pbw
Grass, leaves and green twigs [django, Sep 21 2008]

Benjamin Thompson, Count Rumford, suggested balls made from powdered charcoal and coal bound with clay in the late 1700s. He should be an honorary halfbaker.
-- spidermother, Sep 18 2008

Seriously? That's cool! Do you have a source? So I can reference it when I ask for funding for my project.

I will name the project after Count Rumford, whose idea took more than 200 years to be re-discovered!

But clay, mmm, seems rather problematic as a binder. I think you would need quite a lot of it. Cassava starch is a very effective biopolymer, though, of which you need only a spoonful for a kilogram of charcoal dust. And it burns very well too.
-- django, Sep 18 2008

It's a good idea, but I think it would work even better if it were scaled up. It seems very inefficient to do all this on a small scale, but perhaps local manufacturers could do this?
-- MaxwellBuchanan, Sep 18 2008

Google "D-Lab" from MIT. They charcoal waste corn cobs, amongst other things.
-- 4whom, Sep 18 2008

I couldn't get the link to the slideshow to work.

This sounds promising. If a low tech small scale production facility could be built with only a small investment, this might fit in well with some of the micro-loan programs.
-- scad mientist, Sep 18 2008

[scad mientist] does the alternative link work for you?

Anyone else having trouble seeing the slideshow?
-- django, Sep 18 2008

Vernon took a swing at this concept a few months ago. I have linked it.
-- bungston, Sep 18 2008

I don't understand how this is going to cut down on defenestration.
-- normzone, Sep 18 2008

[Normzone] if people no longer build windows, defenestration rates will drop dramatically!

They would need more fire to lit their homes, though, which might increase deforestation.
-- django, Sep 18 2008

The alternative link works for me. I was hoping that the slideshow would include the process for making the charcoal as well, but I see you just documented steps 2-7. Step 1 seems like it would be the most difficult part to implement in developing countries.

I think this is a complementary technology to the Solar Tar Still. This idea takes one of the outputs from that process and makes it more useful.
-- scad mientist, Sep 18 2008

[scad mientist], in fact, making charcoal from crop residues is pretty easy.

I used a "barrel in a barrel technique". You put the residues in one barrel, which you place upside-down in a larger barrel, so that it creates a limited oxygen environment. You surround the small barrel with fuel to heat it, which you put also in the large barrel. This larger barrel has small holes at the bottom, which draw in air to get the fuel going.

Once the trash in the small barrel starts to pyrolyse, it releases pyrolysis gases, which escape from the bottom. At this bottom, you now find hot fuel, which burns off the pyrolysis gases.

After a while, you only have pyrolysis gases coming from the trash, which suffice to keep the reaction going.

When all the gases are burned off, you have charcoal.

See link for this very simple process.

I will put up some pics of my own charcoal maker, soon.


The Solar Still is certainly interesting, but it works with much higher temperatures. It's basically solar-chemical processing, which is an old field of research.

See the huge solar furnaces that are used for research into solar-chemical biomass conversion. Because they can reach such high temperatures, they can basically destroy anything. They're also used as experimental aluminium smelters.
-- django, Sep 18 2008

1: What was the starting material for the charcoal pellets in the video?

2: What happens if you include plastic in the crop waste feedstock?

3: If it is easy (and it sounds easy), why aren't third worlders doing this already? Has no-one thought of it? If I were a charcoal maker, and it was hard for me to get the stuff I usually made charcoal from, I would try making it out of something else.
-- bungston, Sep 19 2008

[Bungston] good questions.

1. the trash I used were green twigs, dried tall grass and leaves. Because I'm not in a tropical country for the moment, I haven't experimented with the suggested feedstocks. But I've tried to find materials that resemble these (e.g. the twigs I used were similar to cassava twigs in density and thickness - chemical composition may of course be very different.)

I just wanted to try to make charcoal out of non-wood feedstock.

2. Plastic would melt and carbonise too.

3. I think third worlder's are not doing it because they just don't know the technique. There's one NGO, called ARTI, which won the Ashden Awards for developing a similar technique to use sugarcane tops instead of wood - I think.

Perhaps they're not doing it because they couldn't imagine using cassava starch as a binder - it's basically food, and maybe that puts them off. However, from my test it looks like you need only very limited quantities of it.

Finally, a reason could be that it is labor-intensive. The local circumstances might make it so that gathering wood is less of a burden, even though you may need to walk long distances.

A field trip should be organised to find all this out. Maybe [MaxwellBuchanan] should come along and study whether indeed it might be more economic and efficient to scale things up. I'd definitely invite [scad mientist] too, because he will look at opportunities for micro-finance and micro-enterprise...!
-- django, Sep 19 2008

This is slick. Other thoughts.

1: How much heat is required to generate the charcoal? I see in your link you use firewood to fuel it. After a first run with firewood, can you fuel the double-bucket cooker with pellets from a previous run and produce more pellets than it consumes? This sort of thing is where scaleups might be more efficient.

1.5: I have linked what I thought was a truly halfbaked scheme (my home charcoal distiller) but actually your 2 bucket system is 90% of it. If you filled the outer bucket with scrap metal, could you power charcoal production with a fresnel lens? Could you omit the outer bucket and place the inner bucket (now directly heated by fresnel) upside-down in a tray of sand, to allow exit of pressured pyrolysis gas but limit entry of air? If so you sidestep the need for firewood. You could still cook dinner on top. But you still might need a field trip as I am not sure how sunny it gets in Belgium.

2: Other binders. As you say, cassava is food. Clay is a binder for other uses. Maybe these pellets can be agnostic as regards binders.

3: Poop. It is labor intensive to collect ag waste from fields (less so at sites where it is processed). Poop from domestic animals in a pen must be collected anyway. Cow / goat / elephant / sheep poop would be a good feedstock. You could find that in Belgium.

4. I do not think your pellets would be hydrophobic. I think they would be very hydrophilic because the components are hydrophilic. I think they will fall apart in conditions of humidity. I still like them.
-- bungston, Sep 19 2008

on watching the slide show I see that the charcoal must be cooked with the cassava starch. This cooking could be done using the heat from a subsequent batch, instead of using that heat to cook dinner in a wok.
-- bungston, Sep 19 2008

[Bungstong] the idea to use the heat from the fire of the pyrolysis gases, to cook a batch of charcoal with cassava, is a good idea.

Because to cook the charcoal + water + cassava starch, you need to bring it to boiling point.

Until now I only used the heat from the combusting pyrolysis gases to dry my feedstock. But you don't need such high temperatures to dry feedstock, you can let it dry in the sun, and use the high temps for cooking the charcoal and water and cassava.

I will try it out and take some pics.
-- django, Sep 20 2008

For [scad mientist] and others who may be interested: I added the slideshow showing the feedstock and how to turn it into charcoal with the "barrel in a barrel" technique.

Note that, when the pyrolysis gases escape, they burn very cleanly.
-- django, Sep 21 2008

I wonder how much the heat from the fire of the pyrolysis gases contributes to heating and creating the charcoal? How much do they add over the firewood alone?

If they only burn on escaping and encountering oxygen, much heat is probably generated above the level where it can heat the inner bucket and contribute to charcoalification. Fine for cooking on top, but ideally this heat could save on firewood or other fuel needed to make the charcoal.

I am reminded of the hamburger cooking method which uses a piece of newspaper as fuel, the fire from that point on being fueled by grease escaping the cooking hamburger above.
-- bungston, Sep 26 2008

The problem with this is it's entirely baked : charcoal briquettes are made out of junk like straw - carbonised, compressed and glued together with starch.

I pointed this out some time ago, but I see that my annotation was deleted.
-- Loris, Jun 01 2009

random, halfbakery