Fuel for the fire? char for the chard? Carbon for the compost?
The feed-back loop is a standard example of what I’ve heard of as systems theory, it boils down to “Repeat any action for long enough, and the side effects of this action, no matter how slight, will become apparent”. Here at Melliodora and throughout the Permaculture world (and probably that of most pre-affluent societies) these side affects are made into opportunities wherever possible, eg. foodscraps for chickens, waste composting and topically, hard green waste from the goats’ fodder.
I refer here particularly to the medium sized, spindly branches left from the goat fodder once the resident Caprines (Bette, Tans and the newly foliarly initiated, Chops) have stripped them of leaves. Last season I chipped the whole lot on wet days (a good undercover job for precipitous weather), this season I’ve tried my hand at char – twice, and have found the process failing in a number of respects- 1. The twigs are still a little green 2. This means that a huge amount of acrid smoke is given off 3. The drum I am using for the burn doesn’t quite seal 4. The amount of char produced in a burn is about one eighth the volume of twigs 5. Much of the char that it does produce is not properly burnt, and so the char is fairly woody, rather than char-y. The benefits of char burning are as follows – carbon sequestration, labor saving, not using fossil fuels and I have processed it such that there are 1-2 in thick sticks perfect for getting a roaring hot fire going in the combustion stove, and probably in the future cob stove to built in the Tea-House. Still I am concerned that burning the wood now
So I have serviced the chipper in preparation for a good stint of chipping which has a number of good points – it renders the wood easily decomposed, it gets rid of all sizes of branch upto 3 in thick, it gives me something to do when it’s pissing down rain. Bad points; burning fossil fuel, air pollution, noise pollution, the need to wear safety gear, after two or three hours, it does very strange things to your brain, namely a shuddering effect to nerves and eyesight. And the 3in + pieces are perfect for stoking up the combustion stove nice and hot inside.
So I’m torn, caught in the throws of a Permy dilemma. Ultimately I just want the bloody stuff to break down into usable carbon that will happily cart essential nutrients and trace elements up the roots of me plants. I don’t want to fuck the climate, and I don’t want that lignin in the woodchips pinching all me precious Nitrogen from me soil. I reckon I’ll chip on for a while and work on a better burner when I’m ready…
July 21st, 2007 10:31
‘Scuse my ignorance, but what do you use char for?
July 21st, 2007 11:27
yo mick.
char = short for charcoal i think. there’s two main uses:
* a hot burning, smoke free fuel source
* a soil aditive
on the first, our patron david has suggested using charcoal as a city fuel, the hot flamable (and relatively poluting) gases which are produced during the initial burn of the wood can fuel out of city industry. this within a sustainable forest managment framework, something we’re not very good at in aus. i know oliver has also made it so he can do some black smithing (making a knife from some old farm machinery steel.)
on the second, the word i’m getting from dr elaine ingham (just finished her soil foodweb course in lismore) is that it’s a waste of energy to add char. currently there’s a fad of adding it to soils to sequester atmospheric carbon. charcoal is pretty inert in the soil. google ‘terra preta’ to find out about the much hyped amazon soils created by incans. one of australias top government scientists is promoting a program called agrichar, which takes sawmill waste (and he claims landfill — but that’s going to be ugly) and turns it to charcoal as a soil additive. elaine’s take is why? you’re burning off a lot of the good stuff, you’d be much better making compost with it. charcoal adds some fluff to the soil, but not much else. compost adds humus, nutrients and soil life.
seb, whatchyou reckon?
July 22nd, 2007 14:14
Well, It is a dilemma after all.
The energy, time and space necessary to compost twigs and sticks makes it pretty prohibitive, as does the potential for such dry fuel to become a fire hazard in Summer. Chipping them speeds up the process, but unless it’s pretty well broken down you are left with a material that pretty efficiently sucks vital Nitrogen from the soil and uses fossil fuel (ironically burning carbon to process carbon). Also from my personal experience, there are extraordinary improvements in the structure and moisture carrying capacity of soil (or compost) with char added – very important in temperate Australian summers which are long hot and dry. The structural improvement may suggest that char provides a supplement of colloids to soil, helping to break up peds (small chemically bound lumps of dirt) and in turn aiding moisture retention and accessability of nutrients.
In contolled experiments seedlings grown in average clay with char added have a strike rate of 85-95% VS 35-65% without char and look generally larger, greener and more vital.
July 22nd, 2007 14:21
Oh yeah, dean the blacksmith uses coal from his slow combustion stove, for his furnace. This is permie as, for he heats his house and his water (probably cooks as well), sifts the coal from the ash and reuses it in his furnace.
Hows that for one action many functions?
It should be noted he uses only hardwood eucalypts, and decent sized blocks at that. Also that slow combustion is very different to our fast combustion stove here, which produces almost no coals, while the slow combustion is a major contributor to smog (airborne particles) and greenhouse gases. Taking this into account Dean is trying to source yellow cake to fire his furnace…
We’ll keep you posted on that one.
July 24th, 2007 18:31
Ah.. very interesting. A friend’s father used to have a small aluminium and brass foundry in his shed, powered by charcoal. It was fed by a fan, but seemed to burn quite cleanly.
I have also heard that wood gas is a very efficient way to extract energy from biomass — though fairly troublesome to implement.