[Stoves] ETHOS Discussion about decentalized stove efforts

[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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