[Stoves] Calculating cooking costs and char costs ----Re: [biochar] Where to discuss STOVES AND CARBON offsets and drawdown

[Frans Peeters]

Nikhil,

 

Very good ! SUBSIDIES for dunge !

 

   Here we sell  bukets with dry cow dunge fertiliser !    For ladies their AZALEAS .

If you sell  HOLLY COW DUNG ……it must be stil better business !

 

Regards

F.

 

Van: Stoves [mailto:stoves-bounces at lists.bioenergylists.org] Namens Nikhil Desai
Verzonden: dinsdag 19 september 2017 20:23
Aan: Discussion of biomass cooking stoves
Onderwerp: Re: [Stoves] Calculating cooking costs and char costs ----Re: [biochar] Where to discuss STOVES AND CARBON offsets and drawdown

 

Crispin:

Thank you for pointing out market signals due to fertilizer subsidies. Very interesting. 

China also must have a great deal of animal waste from the food industry - couldn't that go to fertilizer and climate char? 

 

CDM and GS computations are driven by theories that have not been validated in practice.  Invent a theory that can win a nod by opaque methods signed off by a technical advisory council stacked by pals, and gold taps will open. 

Nikhil

 


On Sep 18, 2017, at 3:21 PM, Crispin Pemberton-Pigott <crispinpigott at outlook.com> wrote:

Dear Paul

 

>Beginning with the baseline fuelwood use of 187,800 kg of fuelwood per year per village, if we assume a 10% moisture content, the baseline fuelwood is equivalent to 170,700 kg of dry fuelwood.

 

Correct.

 

Convert that to char using a pyrolytic gasifier and you get 25% of 170,700 = 42,675 kg of charcoal (not carbon).

 

The carbon fraction is probably about 36,300 kg.

 

Of the original carbon some 170,700 x 50% = 85,350 kg of C, minus 36,300 = 49,050 kg of carbon which creates 179,850 kg of CO2.

 

As pointed out here years ago, the challenge for pyrolytic stoves to have a heat transfer efficiency that more than makes up for the additional fuel requirement. If you look back far enough I provided a formula for calculating the requirement. 

 

As whole-wood burning cooking stoves have reached the 33-35% efficiency range, the efficiency of a gasifier has to be high enough to compensate for the additional fuel, if the fuel savings matters to the project, which in the case of CDM and GS it does. If the char retention is 25% of dry mass, and that fraction contains 50% of the original energy in the fuel (at least), then the stove will have to be twice as efficient as the wood burner, i.e. 66-70% heat transfer efficiency. In theory it is possible, in practice I haven’t seen it. All pyrolytic gasifiers consume more fuel than the best wood burner available at the time.

 

Your stoves might compare favourably with an open fire or a declared 10 or 15% efficient baseline, but they will not be as fuel efficient as a stove that burns wood completely.

 

A stove that burns wood completely paralleled with a small charcoal making operation in the same community might use less total wood and produce more total char because both technologies can be optimised to their function. If the purpose is to create the most char and the most cooking from a given source of biomass, so at least, a pyrolytic gasifier is not the best option. It is an option but it is not yet out-competing other technology combinations. The cleanest wood burning stoves are as clean-burning as an LPG stove, or there is not enough between them to find a meaningful difference. 

 

If one can sift through a biomass source and take out everything ideal for a wood burner, and pyrolyse the rest into char, that is a reasonable thing to do if the char has a use or value. 

 

I proposed two years ago that in Hebei, which has a serious problem with air pollution caused by the in-field burning of crop residue, that they put a small price on the material making it worth collecting it to a central point. This could be charred while making wood gas that can be piped into the local distribution network. The remaining char would go into the input line of local fertiliser factories that are making organic fertiliser, of which char is one component. There are multiple factories making these products, almost of all of which is sold outside the province to others which subsidise organic fertiliser products (Hebei doesn’t).

 

They are not so unsophisticated as to advocate randomly planting char in the soil. They make compounded fertiliser products designed for typical or particular applications. I think it is a good use of millions of tones of agricultural wastes. So far they are not doing it.

 

Regards
Crispin

 

 

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