[Stoves] stoves and credits again

Sun Sep 24 16:56:00 CDT 2017

Dear Paul

>Charcoal is an attractive fuel.   Too bad it is made by processes that throw away 2/3rds of the energy.

Careful there. Let's calculate and not bandy about convenient numbers.

A very good charcoal making operation produces more than 35% of the input dry mass as dry charcoal. That is the minimum to be able to sell in the EU market.

Suppose the input fuel is 16 MJ/kg and the output char is 29.5 MJ/kg. The maximum output is about 45% mass but let's go with 40% as a max. At 40% we have 16 MJ input and 29.5*0.4 = 11.8 MJ which is 74% of the original available energy. This is a lot more than 1/3.

In order to reach the nadir of 33% of input, it means the charcoal yield would be no more than 18%. While obviously there are producers making far less than that, but they are not upheld as the way forward. A useless producer of char is no more useful as a guide than a useless stove. A very modest charcoal operation is going to deliver 30% of the dry mass. That means it delivers 0.3*29.5/16= 55% of the energy ‎available in the original fuel as dry charcoal.

Next one must consider the efficiency of a charcoal stove next to the wood stove with which it will be compared. A decent charcoal stove has a fuel efficiency of 50%. Examples include the Anglo Supra and the Anglo Supra Nova in ‎Indonesia, both low cost and in the public domain. A very good wood stove will be 33% efficient. Most are less.

Thus on an available technology basis, not taking the limiting technologies at the cutting edge, we get a wood fuel energy delivered to the pot of 16*0.33= 5.28 MJ and a charcoal fuel energy delivered of 16*0.55*0.5= 4.4 MJ. This is 21.5% less energy delivered, with far less smoke in most cases.

How much would the char production have to improve to make them equal opportunity energy carriers?

38% char delivered would put them on an equal footing, about what any producer has to attain to sell to the EU market. So it is not uncommon.

That number is midway between a low cost Adams charcoal maker and the top line rapid pyrolysis process from Hawaii.

Lastly, before finishing, we should note that charcoaling wood permits the use of fuel that would never be used as 'wood' because of its shape: stumps, roots, knots, notches and burl.

If the same calculation above were to be made based on a whole tree, the charcoal might well come off better on total energy delivered to pots. It is of course a far superior fuel and is widely traded even in rural areas, as discovered by recent investigations in Sudan. There is a lot of charcoal coming to a neighbourhood near you.

Regards
Crispin

Philip, Tom and all,‎

Philip is mostly correct.  Actually wood takes up (has) too much WEIGHT.  Wood has 3 times (or more, if the char is poorly made) the ENERGY value of charcoal that could come from that char.   But it has about 5 times the DRY weight of the char, plus there can be 20 to 50% moisture  content to make the wood even heavier.

And the charcoal has  almost double (30 vs. 16) the energy content by weight, but char is so much lighter per unit of volume.  So the trucks are buldging upward and sideways with the sacks of charcoal strapped to them.  Weight of charcoal is not a problem for most transport.

Apart from the transportation issue, I believe that the appeal of charcoal is that it does not smoke (not much).   CO is invisible and deadly, but the people learn to cook on the balcony or keep some  air flowing.  And it does not turn the bottom of the pots black.

Charcoal is an attractive fuel.   Too bad it is made by processes that throw away 2/3rds of the energy.    (So, let's promote TLUD stroves and collect the char for sale to the urban folks.  Only one third of the cutting of wood/forest.)

 So, if 100,000 households (mainly in rural or peri-urban areas) would use TLUDs, the resultant char would equal to the energy needed for an approximately equal number of households (mainly urban) that would want to burn charcoal.

Now that would be FUEL efficiency measured by communities, not by single stoves.

Paul

Doc  /  Dr TLUD  /  Prof. Paul S. Anderson, PhD
Email:  psanders at ilstu.edu<mailto:psanders at ilstu.edu>
Skype:   paultlud    Phone: +1-309-452-7072
Website:  www.drtlud.com<http://www.drtlud.com>

On 9/24/2017 11:40 AM, Tom Miles wrote:
That's probably why charcoal use is increasing 5% per year in SSA compared with wood fuel at 1% per year.

T R Miles Technical Consultants Inc.
tmiles at trmiles.com<mailto:tmiles at trmiles.com>
Sent from mobile.

On Sep 24, 2017, at 8:50 AM, "plloyd at mweb.co.za<mailto:plloyd at mweb.co.za>" <plloyd at mweb.co.za<mailto:plloyd at mweb.co.za>> wrote:

Just a thought on Sub Saharan charcoal use. As Africa urbanizes, so it needs energy to cook. Wood takes up too much volume, and the roads are primitive. So it makes sense to use charcoal. A bicycle load will keep ten homes cooking for a week.
The use of char oal has everything to do with logistics and nothing to do with the environment.
Philip

Sent from my Huawei Mobile

-------- Original Message --------
Subject: Re: [Stoves] stoves and credits again
From: Nikhil Desai
To: Ron Larson
CC: Andrew Heggie ,Crispin Pemberton-Pigott ,Discussion of biomass cooking stoves

Ron:

What makes you believe that users of biomass-fuelled stoves are predominantly growers (of biomass)?

Saw the figures for urban charcoal markets in Sub-Saharan Africa lately? Or looked at non-household cooking (in my view roughly 50% of cooking energy consumption worldwide)?

Nikhil

On Thu, Sep 21, 2017 at 10:54 PM, Ronal W. Larson <rongretlarson at comcast.net<mailto:rongretlarson at comcast.net>> wrote:
Andrew and list:

There appears to be a win win situation here and I gather there is
still a vast part of equatorial Africa where annual burning  takes
place. However it brings me to another reason I like the idea, though
not the practicalities, of a householder-subsistance farmer being paid
a subsidy funded by the developed world. The trouble is I have a
parochial view and not a good worldview of what types of persons
depend on biomass fuelled stoves. Are they also predominantly growers?

[RWL9:  Yes to Andrew’s last question.  I disagree with Andrew calling himself “parochial” - when he supports (as do I) the ethics of “a subsidy funded by the developed world”.

[RWL10:   Agree totally.  And I think this is what will eventually kill the geoengineering technology that is often placed ahead of biochar - BECCS.  In BECCS, as with “clean coal”, the CO2 from combustion (never pyrolysis) is placed, as  liquid, deep underground.   Major expenses needed to protect the world’s soil are not needed for biochar.  Soil quality is closely linked to carbon content - and biochar does this with no penalty - while apparently being the cleanest and most efficient of all possible solid-fuel stoves.

`Andrew - thanks for your above rebuttal to Crispin.

Ron

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