[Tiabin]

I'm looking at taking an adventure into homemade terra preta. The question I have is... What is the correct way to go? I'm willing to try making it, but I'd like to know what the most effective method (and simplistic) is so far for making it... but in addition to that is it, easier and/or superior to just buy charcoal at the store, charge it, and pulverize it?

I'm starting a massive compost, mostly consisting of used coffee grounds. I thought this might be able to be used for char as well if I go the do-it-yourself route.

Any thoughts?
By the way, I'm from Memphis, TN also. I saw another member on here is from there.

[freeztar]

Originally Posted by Tiabin

I'm looking at taking an adventure into homemade terra preta. The question I have is... What is the correct way to go? I'm willing to try making it, but I'd like to know what the most effective method (and simplistic) is so far for making it...

Get a metal trash can and start a big fire in it. Once it is going good, dump a whole bunch of the material to char on top of it. Place the lid on top with a slight crack to let fumes out. Let it sit until no more smoke is coming out. Let it cool and then open it up to get your char.

but in addition to that is it, easier and/or superior to just buy charcoal at the store, charge it, and pulverize it?

Buying from the store is an option, but it is expensive and not as environmentally conscious.

I'm starting a massive compost, mostly consisting of used coffee grounds. I thought this might be able to be used for char as well if I go the do-it-yourself route.

Check out the thread on coffee and TP in the TP forum.

[Tiabin]

Hi freez! Thanks!! The reply makes a lot of sense. A few pretty simple questions: How big should I make the crack? Are we talking minute, or big? Like should I bury a hatchet in the lid for this crack?

Do I throw the stuff I want to char on while the fire is roaring and throw on the lid, or after it's died down? Should my materials be really dried out first, or can they be a little bit damp?

Thanks a lot.

[freeztar]

Originally Posted by Tiabin

Hi freez! Thanks!! The reply makes a lot of sense. A few pretty simple questions: How big should I make the crack? Are we talking minute, or big? Like should I bury a hatchet in the lid for this crack?

Keep in mind I haven't actually personally done this yet, but from what I've read, you want about a 0.5 to 0.75 inch crack. Basically, you want to make sure that you are limiting oxygen supply to the point that the fire goes out, but not too much, so the fumes can get out. A word of caution here. If the material is not done charring yet and you lift the lid, it can imediately burst into flames and potentially come roaring out at you. Listen for any noises first and make sure the whole setup is cool before you take off the lid and you should be fine.

Do I throw the stuff I want to char on while the fire is roaring and throw on the lid, or after it's died down?

Throw it on when the fire is burning good, and then put the lid on right afterwards.

Should my materials be really dried out first, or can they be a little bit damp?

As long as they are not 'wet', it shouldn't be a problem, but keep in mind that the more moisture the material has, the more smoke will be produced. This can become problematic in urban/sub-urban areas or in any situation where you have people nearby that might complain.

Thanks a lot.

You're welcome.
Let us know how it goes.

[Tiabin]

Freeztar,
Is the consensus to always BURY and/or TILL in the charcoal? Or can it be sprinkled on top for good effect?

[freeztar]

I've heard of both approaches being used. I'd recommend experimenting.

Personally, I would till it in during fall and let it "settle" until spring.

[Michaelangelica]

Not exactly on topic but I didn't want to start anew thread just for this

Green Your Barbeque: Choosing Between Charcoal and Gas
Grill greener with these tips on choosing your hardware
The basic issue is this: charcoal is dirtier, but can come from renewable resources; gas has a smaller carbon footprint, but is derived from non-renewable fossil fuels. Most charcoal is a funky amalgamation of things like sawdust, corn starch and lighter fluid; when it's burned, it can result in 105 times more carbon monoxide than burning propane and lots of harmful volatile organic compounds. But, "real" charcoal, also commonly known as "chunk charcoal," doesn't have the nasty additives, and burning it is carbon neutral. So let's look a little more closely at the numbers.

When it comes to carbon emissions, gas-powered grills win in a landslide. Tristam West, a researcher with the Department of Energy's Oak Ridge National Laboratory, compared the carbon output of gas, charcoal and electric powered grills when producing 35,000 Btu's per hour, a typical industry baseline.
West's calculations showed that gas produced 5.6 pounds of carbon dioxide each hour, compared to 11 pounds for charcoal.
As mentioned above, electrical grills produce a whopping 15 pounds of carbon dioxide for every hour at 35,000 Btu's, so aren't the best choice from the carbon perspective.

After all this, here's the bottom line: go for gas. Lump charcoal is becoming increasingly available, but often comes from thousands of miles (or even multiple continents) away, which negates some of its carbon benefits; until it's readily available from local sources, the efficiency of gas wins out.
Stay tuned for more tips on green grilling, and happy barbequing!

Green Barbeque: Choosing Between Charcoal and Gas : Planet Green
I have a couple of problems with the logic/conclusions here
1 when natural gas is harvested it usually comes up with a large % of CO2 (How much? I don't know)
2 Natural Gas is often transported thousands of miles (eg Western Australia to China and California)

[Munin]

When I grill, I build a wood fire, let it settle down to coals, cook my food. Then after the foods done I put out the fire with water. The next day I've got a bunch of charcoal and ash to add to the compost/TP bin. Since the wood would otherwise decay, and some gets locked up as charcoal/TP I'm cooking carbon negative!

[Nitack]

Originally Posted by Munin

When I grill, I build a wood fire, let it settle down to coals, cook my food. Then after the foods done I put out the fire with water. The next day I've got a bunch of char-coal and ash to add to the compost/TP bin. Since the wood would otherwise decay, and some gets locked up as charcoal/TP I'm cooking carbon negative!

Perhaps I am mistaken, but I think you are misinterpreting what is being produced in your process. I think you actually have charred wood (not the same as charcoal). Charcoal is produced when organic material is heated in the absence of oxygen. While you are cooking you obviously have oxygen reaching the fuel. Adding water just stops the whole process. At no point in what you are describing is there an oxygen free heating.

If my understanding of the process of pyrolysis is correct, you might see some charcoal produced in the center layers of your individual pieces of burning wood, where oxygen can not get to the inner layers and they are obviously hot enough to produce charcoal. However unless you are cooking over large pieces of wood, there would not really be any appreciable amount of charcoal. There would be mostly ash and charred wood.

Your process could be utilized to produce charcoal though! Start your fire, cook your food, and if you have something like a Webber grill you could then pile on organic material, put on the lid, and almost completely close the dampers. At that point you would have the heat, the oxygen would quickly be used by the fire, and you would be able to vent the wood gas produced.

But this is all assuming I actually understand pyrolysis.