| Boiling Point No. 21 - April 1990 |
by Ahmed A. Abusam (NEA)
Reproduced from Sudan Energy News, July -September 1 989
It is well known that fuelwood is the primary energy source for most of the developing countries. Furthermore most of the fuelwood energy is used for domestic cooking either in wood or charcoal stoves. There have been a large number of programs and projects to disseminate fuel efficient cookstovesin the developing countries, due to the growing fuelwood scarcity and the low efficiencies of the traditional stoves. However, these efforts have been mostly unsuccessful.
I think that energy conservation is not the main objective for cookstove users. They would rather have a clean, fast and easy to use rue'. Also the efficiency of the improved stove, achieved at the laboratory level is usually reduced when the stove is subjected to personal field application.
It will be useful if the whole issue of the improved cookstoves is reconsidered in the light of our local experience and the international experience gained so far. In this respect I recommend a book published by the Swedish International Development Authority (Improved Cooking Stoves in Developing Countries). This book gives a detailed appraisal of the role of improved cookstoves in the wood scarce areas of the developing countries. I quote the following paragraph from page 132:- "(The conclusion is extremely difficult to avoid. Improved stoves may be justified at the level of individual families. But under practical conditions they are unlikely to have any noticeable effect on national energy consumption; neither are they likely to have any significant effect on reducing the problem of deforestation)".
Energy Consumption in Sudan amounts to about 7 million tons of oil equivalent (T.O.E.) per year, over 82~o of which is in the form of wood, charcoal and other biomass.
Charcoal and firewood are produced by the naturally growing (99%) National Forests. As a result of the excessive use of fuelwood for energy and the expansion of rain fed agricultural areas, forest areas are diminishing. Some studies suggest that, if the current trends are not reversed, all Northern Sudan forests will be depleted by the year 2000. Suggested ways to stop this, are:- regulating expansion of rain fed agriculture, introduction of other fuels for cooking, using improved stoves & improved charcoal kilns, instituting afforestation programs and improved forest management and introduction of fast growing species for plantations. Considering the above mentioned issues, priorities should be set. The availability of the resource should be the first thing to start with, since no one car; conserve or efficiently utilize something which is not there. It can be natural or man made. introduction of fast growing species in Sudan at this time is an urgent need even if it is only to spread seeds during the rainy season.
The term "efficiency" has got different meanings with regard to the different stages of fuelwood processing. When speaking about efficiency during the time of charcoal production, it generally means the percentage of heat retained in the useable charcoal during transportation time. It is defined as the percentage of energy used to transport fuelwood. It might also be defined as the percentage of useful fuelwood energy that is utilized by the consumer. The efficiency of the stove is the percentage of heat utilized compared to the heat originally contained in the fuel used.
It is to be mentioned that the efficient use of fuelwood is not determined by only one of the above mentioned. It is a combination of production, transportation, user and appliance efficiences.
Whether our charcoal kilns are efficient or not is a matter of debate. Some researchers say that our kilns are fairly efficient.
It has been mentioned, by some researchers, that transportation of fuelwood beyond a certain distance (400 km.), is a rather fuel consuming process. The supply of fuelwood to Khartoum (major consumer) from Damazine area (major producer), has far exceeded this limit.
From personal experience, one can safely say that user efficiency plays a big role in determining whether the fuelwood is efficiently used or not.
The efficiency of the stove is defined as the percentage heat utilization assuming that the user has no role. It is to be noticed that most of the current stoves in Sudan are not affecting the combustion process. They are just acting as holders or carriers for the fuel and/or for the cooking appliance. In addition they provide some protection against the current of the air, thus decreasing cooking time. Some stoves partially work as heat conductors. The heat losses are mainly due to direct and/or indirect radiation.
The available types of stoves in Sudan are the traditional stoves (wood stove & charcoal stove) and the improved charcoal stove. The recorded efficiency of the traditional charcoal stove is of the order of 17%, while that of one of the improved stoves (Sorour)is about 295c.
Taking this into consideration and being optimistic one woukl suggest a maximum efficiency of 30% at the household level. The efficiency achieved through improved stoves can easily be jeopardized by the user.
From the above, it seems to me that the first priority should be given to the plantation of new forests with fast growing species to replace the removed ones. Secondly, there should be a public awareness campaign to increase the efficiency of the user. If it proves to be true that the transportation of fuelwood is a fuel consuming process, then the cost of this fuel should be diverted to a more efficient source of energy e.g. kerosene, Butagas, electricity etc. Before the dissemination of any improved stove, it should be studied thoroughly and its efficiency should be proved.
Ed Note: The paper does not indelicate how the stove efficiency figures are obtained: are they' "Boiling lFater" tests or "Kitchen Performance' tests and do they represent the effective savings likely to he achieved in a household or village.