[Stoves] ETHOS Discussion about decentalized stove efforts

Tue Jan 14 03:38:29 CST 2014

Dear Abelnour Samer, dear Kevin Chisholm, dear all,

There is probably no general answer on the
question of dominating causes of deforestation, because it depends on the local
conditions, but it should be considered that an urban household causes every
year the logging of 8 tons or more of mature trees, when the family is cooking
with charcoal. By multiplying this by the number of families of the city, the
total annual consumption can be calculated. Deforestation can be done at a
distance of several hundred kilometers from the town because charcoal can be
transported easily. The greenhouse gas emissions of this family, caused by
deforestation, is equivalent to that of a car journey around the globe
each year. If the cooking is done with fuel wood, thin branches can be used,
without logging of the tree.

The dated FAO study refers on fuel wood. For charcoal, there are special studies (e.g. CHAPOSA   Studies), these prove in detail the
relationship between charcoal use and deforestation. For fuel wood use, however
bushes can be planted to enable harvesting of thin sticks every year, so that a
sustainable supply is possible ("energy plantations").

On the issue of thermos-technique: The theoretically required energy for 
heating and holding hot an egg is below 20 kWs resp. 20 kJ (assuming a 
weight of 60 g and the specific heat of water, which surely is higher 
than that of eggs), this means that using a 1 kW-heater, theoretically 
20 seconds are needed. Also this example shows that the potential for 
savings is enormous. The advantages of the thermos-technology ("cooking 
with retained heat", "fireless cooking", etc.) are described in detail 
in the Internet (e.g. from Practical Action). The production of a hay 
basket in the manner described is so simple that I want to recommend 
practical experience for everyone. Thermos-technology should be part of 
primary education worldwide. It is critical that for simple solutions 
the insulation can be easily dried after use (advantage of a basket with 
pillow-insulation), that there is enough hot content in the pot, and 
that the insulation does not allow heat convection (pillows should be 
hold together with a cloth).

I remember a report (from Aprovecho ?) with
the test of cooking meals both with and without thermos-technology. With
thermos-technology the difference of consumed fuel wood between of the
different stoves was small and the consumption at all was very low.  I learned in Africa that cooking of beans is
often abandoned, because after four hours cooking on a charcoal brazier the
cook has got a headache and because the charcoal consumption is too expensive. These
four hours of cooking can be reduced to about half an hour, consuming appox. 330 g of
thin sticks for boiling 6 kg of pot content.

With kind regards
Dieter

Am 13.01.2014 19:44, schrieb Kevin:
> Dear Dr. Seifert
>
> How much energy does it take to cook various foods?
>
> For example, take a single egg... if I took a single egg and placed it in a "Retained Heat Cooker" that had a very large thermal mass, how much heat energy would be drawn from the thermal mass to warm the egg to cooking temperature, and to supply the heat necessary to complete the cooking reaction?
>
> If you don't know the energy to cook an egg, perhaps there is some other "standard food", such as 1.00 kg of potatoes, rice, carrots, beans, etc. Perhaps there is a Table showing the energy required to preheat foods to cooking temperature and complete the cooking reaction. Such a Reference would be very helpful.
>
> Thanks!
>
> Kevin Chisholm
>
> ----- Original Message -----
>    From: Dr.-Ing. Dieter Seifert
>    To: stoves at lists.bioenergylists.org
>    Sent: Friday, January 10, 2014 3:04 AM
>    Subject: Re: [Stoves] ETHOS Discussion about decentalized stove efforts
>
>
>    Dear all,
>
>
>
>    My name is Dieter Seifert and I am active in the area of renewable energy (e.g. parabolic solar cookers), together with my family, for about 30 years.
>
>
>
>    Maybe some quantitative considerations in the debate on the question of decentralized cooking power supply are helpful. Using the combination of efficient stoves and the "thermos technology" (cooking with retained heat), only small amounts of fuel wood are consumed, so that a sustainable supply is possible. Refering to data from Table 2 in the article of R. Bailis "Wood in Household Energy Use" in the Encyclopedia of Energy, Vol. 6, Elsevier (2004) , p . 518 (for Nairobi as example for urban households):
>
>    a) consumption of firewood with open fire: 1626 to 3250 kg firewood per household per year at 10  to 20 percent efficiency;
>    b ) consumption of charcoal with improved or regular stove 531 to 1238 kg charcoal per household per year at 15  to 35 percent efficiency .
>
>    If we assume that the charcoal is produced with the conventional conversion factor of 6 tons of wood per ton of charcoal, then this corresponds to a consumption of 3186 to 7428 kg of wood (mature trees!) per household per year. The consumption of wood or charcoal may be much higher in countries with higher forest cover still present.
>
>    If we consider a household that uses an improved stove with more than 30 % efficiency and the thermos technology, then the consumption per household per year can be reduced to approx. 600 kg of wood (thin sticks, not trees). This can be achieved by a stove with grate and with shielding of the pot and, for example, 1 or 2 hay-baskets with a straw pillow under the pot and cotton pillows around the pot and on the lid of the pot - and enough hot pot contents. The firewood consumption is thus reduced to a small percentage (less than 10 % compared to charcoal-use).
>
>    The hay baskets are a typical appropriate technology and it is inconceivable that the wonderful opportunities of thermos-technology are still very limited, concerning to the avoidable damage to the health and prosperity of families and to the environment.
>
>    The supply of urban households with the thin sticks is an opportunity for income generation. The support of this change should be recognized as a public task. In contrast to the established charcoal supply for urban households these incomes are sustainable, as it is only a matter of time when the incomes from charcoal will cease (with growth rates of the urban population of over 3 percent, i.e. doubling of urban population every 20 years) as the sources dry up and the country is deforested.
>
>    The necessary measures can be accomplished in a decentralized manner; but the necessary information and practical advice could be disseminated through the global education system, as we know that for the acceptance of the required change, it is necessary to involve the parties affected, to recognize and realize the challenges and opportunities.
>
>
>
>    With kind regards,
>    Dieter
>
>
>
>    Dr.-Ing. Dieter Seifert
>    Neuoetting/Germany
>    bdiv.seifert at t-online.de
>
>
>
>
> ------------------------------------------------------------------------------
>
>
>    _______________________________________________
>    Stoves mailing list
>
>    to Send a Message to the list, use the email address
>    stoves at lists.bioenergylists.org
>
>    to UNSUBSCRIBE or Change your List Settings use the web page
>    http://lists.bioenergylists.org/mailman/listinfo/stoves_lists.bioenergylists.org
>
>    for more Biomass Cooking Stoves,  News and Information see our web site:
>    http://stoves.bioenergylists.org/
>
>
>
>
> _______________________________________________
> Stoves mailing list
>
> to Send a Message to the list, use the email address
> stoves at lists.bioenergylists.org
>
> to UNSUBSCRIBE or Change your List Settings use the web page
> http://lists.bioenergylists.org/mailman/listinfo/stoves_lists.bioenergylists.org
>
> for more Biomass Cooking Stoves,  News and Information see our web site:
> http://stoves.bioenergylists.org/
>

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.bioenergylists.org/pipermail/stoves_lists.bioenergylists.org/attachments/20140114/b68df998/attachment.html>