Weekend Project #247 - Biochar

(Part 1 of my new ancient elements series: Earth, Wind, Fire and Water - How to Have Fun, Save the Planet, And Usually Not Mortally Wound Yourself in the Process)


How to (Sort of) Make Biochar (Fire, fire, FIRE!)

Careful! This could happen to your potato rake!

Intro:

First of all, you may be asking yourself the usual question that comes along with every post I write: "What the hell is he talking about?!?"  Good question.  As in most cases, I really don't know either.  But, for those of you who are (like me) not yet familiar with biochar, here's the skinny: http://en.wikipedia.org/wiki/Biochar

Holy crap!  There's a lot of science in that article!  You should totally skip that. I'm certainly more comfortable with wikipedia articles that are more along the lines of anything on this list: http://en.wikipedia.org/wiki/Wikipedia:List_of_really,_really,_really_stupid_article_ideas_that_you_really,_really,_really_should_not_create (I really like #13, #38 and #39)

Seriously though, here's the way it works:

The basic idea (as I moderately understand it) is that you take all of your scrap wood and trimmings and whatnot, and get them burning as hot as you can, as quickly as you can.  The little stuff gets the fire burning hot, and the big stuff is what eventually makes your char.  You want as hot a fire as possible so you're burning very cleanly and releasing less smoke (and bad elements) into the air. Then once you're really cooking, and have all the logs you want in there really burning hot, then you shut the whole thing down by taking away all of the oxygen.  The energy that was originally being released as fire will quickly be cut off, but it has to go somewhere.  That energy, limited by the lack of 0₂, will convert to...something....I don't know...but whatever it is smoulders (maybe?) the wood of the logs down to charcoal, preserving the carbon that is normally released into the air as CO₂ in the smoke and gasses of the fire.  And that carbon, as we all know, is great to add to the soil.  Why? Another good question.  And I really don't know.

But from what I've read and have been told, I've been able to piece together an idea.

See, we're all made of up carbon.  Well, that's not true...we're all made up of all kinds of things.  I, personally, am probably 30% bacon and cheese, going with the "You are what you eat" theory.  Still, the basic building-block of pretty much all of the life on this planet is carbon, and somehow that's attractive to the micro-organisms living in the soil.  Those mirco-organisms are what converts the stuff in the soil (nitrogen, potassium, phosphorus, etc.) into things the plants crave (Brawndo*), and the carbon provides the housing for these little guys.  And biochar doesn't provide just basic housing.  Ohhhh no.  Biochar is like a sweet condo with an ocean view and a hot tub in a neighborhood filled with hot models who love to get into hot tubs.

That's Carbon on the right.

No...no, wait...carbon is the house....

Whatever.  You get the idea. It's awesome.

So to sum up, we want to make carbon to add to the soil so the micro-organisms (dudes) are happy and have a place to convert all the nutrients (hot women in swimwear) into plant food (Brawndo).  Admittedly, the analogy falls apart at the end there.  Meh.

*Click for more info on Brawndo

Enough theory.  Let's get to making the stuff.

There are three ways to make biochar:

1. In a kiln/container (the quick way)
2. In a pit/trench (the inexpensive way)
3. The Cameron/Kalewa way.....  as follows:

To be fair, we were slightly confused, slightly uninformed, slightly unprepared, and I may have been slightly drinking (towards the end), so please keep that in mind.  I'll impart lessons learned as we go.

Step 1: Dig a Hole

This part is (lesson learned) not the most fun to do by hand.  But it's good honest work, so who can really complain?  Anyway, the math is easy: if you want to burn a lot of wood (which we didn't) then you need to dig a big hole (which we did).

Step 2: Put Paper, Kindling, Sticks and Logs in the Hole

What we did was make a standard tipi formation in the middle of the pit, and then to put a ring of logs around the tipi, and then cover the logs with brush and other kindling.  It made sense at the time (thinking those were the only logs we'd be burning), but now I know better.  It'd be best to really stack the logs up against the tipi so as it burned down, the logs would move more towards the center/heart of the fire.  But since we didn't do that, it really took a lot of work and hustle to get things working.

Step 3: Light 'Er Up!

Always the fun part of any good fire.  Or flashlight.

The fire started off great.  It was really burning fast and hot, and there was much rejoicing.

It was about this time we learned that there's another step we missed, so I'll add that here.

Step 0: Collect about 3 times more logs and kindling than you think you need.

I guess the logic is that if you're going to all this trouble to do this, then you might as well get as much out of this as possible.  Therefore you want to keep adding more and more material so eventually the whole pit will be full of very hot burning logs.  Needless to say, we were unprepared.  This led to a little over two hours of running madly around the property collecting logs and brush to burn.  So do yourself a favor and and stack up tons of logs and kindling and have it on-hand.

Step 4: Consolidate 

Push the burning logs together, try and keep the heat centered and collected in one place.  If you can do that, the heat will be enough to keep the logs burning without any further kindling.

It is at this point to want to make sure you're not about to drop your phone into the fire while you're trying to take pictures..

Whoops....

Step 5: Shut it Down

Once it's all burning great, then you want to cut off the air.  Some people just throw dirt on everything.  We covered the pit with pieces of metal roofing. and then covered that with the dirt. until we couldn't see any smoke or steam coming up through the dirt.  One recommendation I'd make would be to not wait until it starts raining before covering it up.  I don't believe it had any affect on the fire, but it did turn all the dirt into mud with the consistency of snot.  There were a few "Oh crap, almost fell in" moments.

Step 6: Wait Three Days

It takes a while for the stuff to really cook in there, so best to just let it sit.

Step 7: Dig it Back up

After it's all done, open the pit back up and pull out all your biochar.

As you can see, we got about three tubs worth of the stuff, despite our mishaps.  Next time we ought to get between 3-4 times as much.

That's it!

If any of you give it a go, take pics and let me know how it turned out for ya.