permaculture

[Toby Hemenway <toby@patternliteracy.com>]

Christopher has done a nice job of summarizing some of the merits and 
limitations of biochar—nice work. I know a fair number of people involved 
with biochar on several different levels, and I’ve made some myself. The 
stuff I’ve used definitely improves plant growth and soil water retention.

It’s important to generate it as a by product, and not cut down trees or 
other biomass simply to turn it into biochar. Used in a forest fuel reduction 
program it makes a lot of sense; you’re already cutting the wood, and it goes 
into the soil as long-lasting carbon. And it makes sense if you need heat, 
which most of us do. You get heat and you get biochar—stacking functions. In 
the 3rd world, people make it while they cook food, and then sell the 
biochar, creating a cash crop that has a yield useful to the farmer (heat for 
cooking), unlike, say, raising cotton or bananas for export that just yields 
cash.

Troy Martz (google him) builds a really cool machine that uses biochar to 
generate wood gas that then can run a generator or a diesel car. A 55-gallon 
drum of charcoal will drive a car hundreds of miles.

Making it can be done very cleanly; even an open-air burn can be done with 
almost no smoke, and in equipment designed for the purpose, gases and other 
potential pollutants get re-burned into CO2 and water, nothing else. 

I have a friend who generates short scraps of redwood, and I use that, 
stacked in ricks (like making Jack Daniels whiskey) to make biochar. I then 
charge the char with fish emulsion, compost, and trace elements for a couple 
of weeks and put it in my garden beds. It really boosts growth.

I also like it as a way to turn biomass into long-term soil carbon, as 
Christopher said. Fresh or dry plants put in soil will quickly break down, 
release carbon, and disappear. Biochar will usually stay in the soil for 
years, even millennia.

As with so many other things, making biochar at small, local scales hasa lot 
of benefit, as it can be done with waste materials, build local soils, and 
provide income locally. On an industrial scale, it just means more 
deforestation, pollution, and wage-slavery for the people actually doing the 
work.

My friend Tom Ward makes biochar in an oil-drum kiln (among other techniques) 
and has refined the method so that he can take small, weirdly shaped pieces 
of manzanita, char them, and sell the resulting beautiful “petrified” char, 
still in its twisty original branch shape, to the Japanese at a very high 
price for tea ceremonies. And he makes charcoal that grills up some of the 
tastiest barbecue I’ve ever had. He also makes biochar for the usual use, but 
the special uses are kind of fun. 

In Tom’s system, he heats the wood in a drum until it starts to generate wood 
gas, which happens pretty quickly, and then he lights the wood gas so it 
becomes the fuel to cook the char. It uses very little outside fuel (wood), 
and that is from the same forest fuel-reduction program that provides the 
biochar feedstock. Elegant, and almost no pollution since the wood gas is 
combusted.

As Christopher says, it isn’t for everyone or for universal use, but it has 
its applications in the right circumstances.
 
Toby
tobyhemenway.com

Just out: my new book on urban permaculture, The Permaculture City. Order it 
at your favorite bookseller or get a signed copy from me at  
http://tobyhemenway.com/book/the-permaculture-city/



> On Jul 4, 2016, at 3:38 PM, Gene Monaco <efmonaco@comcast.net> wrote:
> 
> Been reading up on biochar lately, and I get this sick feeling in my stomach
> as if it is surrounded by darkness, cloaked in an illusion.  But I'm often
> wrong.  I get the basic idea of it, but I have some questions I'd like to
> ask this distinguished group, for whom I have a lot of respect.
> 1) The literature seems to be divided as to whether or not it actually makes
> plants grow better.  Some do, some don't.  How could we trust it in a
> permaculture guild?  Experimentation is the best way, but that takes time
> and controls.
> 2) If the idea is to get biomass into the ground without it having a chance
> to break down, wouldn't it be better to re-afforest degraded areas in
> northern climates where winter will slow things down, burying layers of
> carbon over time, rather than talk of tropical plantations to burn
> fast-growing plants into charcoal before burying it?
> 3) Some biochar literature says that the product needs to be made at temps
>> 500C, which seems to me to be a lot hotter than what naturally occurs in a
> temperate forest fire.  Less than that and it's no good.  So how is the
> comparison to charcoal from natural fires or camp fires relevant?
> 4) How do they heat the biomass to more than 500C to make the biochar?  And
> doesn't that produce its own greenhouse gases?  
> 5) And finally, what about building soils?  Seems like the stalks of wheat
> that are a "waste" to big ag, would be better off as organic inputs to an
> organic system.
> What am I missing?
> -Gene
> 
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