Dan and list:
1. This is partly picking up on your ”Is this correct” question below. The
answer is yes.
2. I think you were making your calculations from p 23 of the recommended
report, which said:
A six-year cycle was recommended to ensure maturity. Harvesting
started in 2008 and it emerged that 6-year old acacia trees produce heavier
charcoal than 4-year old
acacia trees. Under ideal conditions and efficient conversion, it has been
estimated that an acre of land
should produce about 300 bags (40 kg) of charcoal.
Using metric, your 7.3 tons biomass/acre converts to about 7.3*(2/2.2)*2.47
= 16.4 tonnes biomass/ha-yr = 1.64 kg biomass/sqm-yr = 0.8 kg C/sqm-yr
(assuming biomass is about half carbon) And these are bone dry tones. Can
maybe double for wet tonnes.
Or, sticking with metric, the harvest is 300 * 40 = 12,000 kg = 12 tonnes char
per acre per harvest, or 2 tonnes char /acre-yr. Same as about 5 tonnes
char/ha-yr or 4 tonnes C/ha-yr (assuming char is 80% carbon). Using your
conversion efficiency of 0.3 (w char to w biomass), this is about 5/.3 = 16.7
tonnes biomass/ha-yr - which is essentially the same that you obtained in
English units. But also 30% is awfully good in any kiln. If they were only
to get 25% conversion, they would have needed to start with an NPP of 5/.25 =
20 tonnes biomass/ha-yr or about 10 tonnes C/ha-yr = 1 kg C/sqm-yr
One reason for going through this is to compare to global NPP averages
which is about 60 Gt C/yr divided by about 12 Gha = 5 tC/ha-yr. Kenya being
twice as large as the global average sounds OK. I’ll bet they can do
appreciably better in those parts of Kenya with enough rainfall.
3. My main reason, however, for following up is to note that this 2010
study by Practical Action nowhere talks about char-making stoves. It also is
full of talk about the illegality of most char making. In the above example,
there is mention only of a six year cycle - no pollarding (like coppicing)
apparently - chopping down the whole tree every six years? I think they can
do a lot more cooking (have faster regrowth of the forests) than with the
assumption of producing char with no use of the pyrolysis gases (which are
presumably not even flared). So I hope for another study by Practical Action
which includes the option of switching from jikos to char-making stoves. That
is - moving wood - not char. It was disheartening to read about the illegal
taxes that hurt the producers. I wonder if there is also illegal taxing of
wood?
4. Not really pertinent here, but when I lived in Sudan, the chief
forester for the country confessed he was (illegally - prohibitions against
introducing exotics) throwing out mesquite seeds at every opportunity. The
seeds of the acacia don’t make it through the local animals (goats, etc), but
mesquite seeds do. He was pleased with his success.
Ron
On Nov 15, 2013, at 3:03 AM, [email protected] wrote:
> Teddy,
> I have read the article provided and found your production levels with
> native acacia to be quite amazing. Correct me if I am wrong. After doing some
> math with your numbers, am I correct? 1 kg = 2.2 lbs, 1 short ton = 2000
> lbs. Divide acerage harvets production number by 6 years to get result.
> You are producing 2.2 short tons per acre/ per year of charcoal.
> Reversing the equation. 2.2 tons charcoal at 30% conversion rate = 7.3
> tons of acacia produced per acre, per year, in 6 harvest cycle.
> Is this correct?
> Wow. Here in Ohio USA we only figure on 1-2 tons wood per acre, per
> year, with typical hardwood scrub overgrowth harvested for fireplace logs
> maybe every 20- 30 years.
> I want to see what happens when we start to coppice black locust like you
> do. My question is,will our numbers be as good?
> If we use your numbers, a blast furance using 1000 tons of charcoal per
> day ( to use a round number) would need 165,000 acres in charcoal production
> to keep up with demand. Still a lot of acerage to smelt maybe 1000 tons of
> iron per day. When that production is first used as building lumber, and then
> recycled into fuel, it does not seem so intimidating. In that case the
> tranmsportation and harvesting costs are already paid for with the first life
> cycle of the wood.
> A study done 10 years ago, stated that we burry 1,000,000 tons of wood
> per year in landfills in only a 3 county area here around Dayton, Ohio. That
> wood, converted to charcoal at 30% conversion rate, would yield 300,000 tons
> of charcoal per year, Almost the same amount of production figured above.
> Some fuel for thought.
> Keep up the great work.
>
> Dan Dimiduk
>
>
>
>
>
>
>
> On Thu, Nov 14, 2013 at 9:43 PM, Cookswell Jikos <[email protected]>
> wrote:
> OK.... as discouraging as the facts may be, the facts are reality, and they
> must be dealt with to avoid future problems.
> 1: Can different species be grown, that have higher Mean Annual Increments of
> growth?
> Yes - at least in East African drylands - the traditional colonial methods of
> silviculture were focused on high land pine and cypress plantations not
> indigenous dry land adapted trees. (which now provides the feedstock for more
> of Kenyas charcoal) Since 1994 we have been experimenting with different
> dryland planting and agronomic techniques (please see
> http://www.acts.or.ke/dmdocuments/PROJECT_REPORTS/PISCES_Sustainable_Charcoal.pdf
> pg. 7) and most of our findings so far have led us to belive that endimic
> tree species managed in a holistic and permacutrual manner produce coppiced
> 'branch' charcoal with an excellent life cycle analysis profile.
>
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