[Stoves] ETHOS Discussion about decentalized stove efforts
Dr.-Ing. Dieter Seifert
doseifert at googlemail.com
Wed Jan 15 02:58:01 CST 2014
Dear Ron, dear all,
Thank you for your friendly comment. One of many reasons for “coupling
solar and wood” is that there are additional applications for
comfortable use of the solar cooker: baking, bottling, preparing juice
or jam and other products which cannot be prepared with stoves which
work on high temperatures. The SK14 and similar solar cookers do not
surpass 200 °C.
to 5.: Concerning charcoal and deforestation, I wanted to indicate e.g.
on the CHAPOSA final report for Zambia
http://cdm.unfccc.int/filestorage/U/8/Q/U8Q6JB2RNAY0TE1VWIM7FXHK453SCZ/Enclosure%202.pdf?t=Mjd8bXplZWk4fDBzZICky7wyB7KwcNOdeS8q
especially on page 27.
I would like to inform you later about my experiences on coupling solar
cooking and wood in a more comprehensive way.
With kind regards,
Dieter
Am 14.01.2014 15:09, schrieb Ronal W. Larson:
> Dr. Seifert cc list
>
> 1. Thanks for the interjection on solar and charcoal for the Ethos conference.
> Good topics. This is a list not likely to ever do much with solar cookers,
> but there could/should be more on hybrid systems. It would be great to hear
> more from you on savings and difficulties in getting households to use your
> concentrators (or box cookers) because of extra time and cost for two systems.
> Any data on health savings?
>
> 2. I may have purchased one of your parabolic systems in 2002 at the Jo-burg UN
> conference. Were you or your company selling there? A very nice product.
>
> 3. For others I recommend this Ppt and especially slide 35 at this site:
> http://images2.wikia.nocookie.net/__cb20100318191240/solarcooking/images/3/38/Parabolic_Solar_Cooker_as_Pedagogic_Instrument.pdf
>
> 4. Similarly good presentation of yours at
> http://images3.wikia.nocookie.net/__cb20080215212112/solarcooking/images/5/58/Smoke_Free_Village_February_2005.pdf
>
> 5. I found plenty of cites to the CHAPOSA studies you recommended (one from
> World bank and REDD was good on Tanzania) and agree there is more concern there
> about deforestation. Do you have a favorite CHAPOSA cite? Or anything else on
> deforestation?
>
> 6. Thanks to Abelnour for his cite (this is a little more convenient:
> ftp://ftp.fao.org/docrep/fao/W7744E/W7744E00.pdf ). Although dated, the
> following excerpt (I think was from Table 4.5), shows me the key data (prices
> might be 50% more since the late 1990’s), but the cost ratio would be similar).
> Why would anyone want to use charcoal now when it costs 3 times as much per
> GJ? And modern wood-based cook stoves can now easily beat the 20% efficiency
> figure from the last century, while the charcoal cookstoves haven’t improved as
> much, I think. Of course making char in a cook stove seems to be making pretty
> good progress as well. (I want the char to go in the ground)
>
>
> Again thanks for bringing the topics up and for all you are doing for solar
> cooking. But to repeat, your experience on coupling solar and wood would be
> most interesting.
>
> Ron
>
>
> On Jan 14, 2014, at 2:38 AM, Dr.-Ing. Dieter Seifert <doseifert at googlemail.com
> <mailto:doseifert at googlemail.com>> wrote:
>
> >
> > 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
> >>
> >>
> >>
> >>
> >> ------------------------------------------------------------------------------
> >>
> >>
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