Efficiency Tests on the New Peko Pe Stove in Uganda

By Per S. Nielsen, Technical University of Denmark, Denmark.

In relation to technical options, the choice of fuel, optimisation of heat transfer, and efficient combustion processes are important. The non-technical options include, for instance, the use of lid, skills in firing control, and organisation of the food preparation process.

The central problem in obtaining high efficiency for the popular three-stone stove in real life is the firing control. With three-stone stoves, it is difficult to obtain the optimal distance between fire and pot and to keep the fire in the optimal combustion state, as heat is lost with large flames.

Peko Pe Tested

The Peko Pe is a newly developed gasifier stove developed by the Norwegian Paal Wendelbo. It is basically a pyrolysis gasifier. (See figure.)

The stove was tested at the Technical University of Denmark and in the Adjumani Refugee Camp in Uganda in 1995:

• In Denmark, the stove efficiency was 24-26% burning dry woodchips (10% moisture) with a caloric value of 16MJ/kg of woodchips.
• In Uganda, the tests showed a stove efficiency of 21-23% with a caloric value of 15 MJ/kg of grass.

In the refugee camp, the stove was tested with 20-cm-long grass straw of two different diameters, 3-4 mm and 7-8 mm. Generally, the thinner grass burned better than the thicker grass.

The stove provided heat enough to boil a meal in around 45 minutes after reaching the boiling temperature. The radiated heat made it possible to boil the water for another 25-30 minutes after the combustion was stopped. This is a so-called charcoal effect. This effect was not seen in the tests on woodchips in Denmark.

Further technical options to examine to improve the efficiency of the stove include: changing the number of holes, the height of the chamber, variation of biofuel source, and specifying the role of the moisture percentage.

Socio-economic aspects

In the camp of 100,000 refugees in Uganda, a workshop was established in cooperation with Accord, a UK NGO and the Norwegian Association for the Disabled.

Technicians, disabled people and women were trained to produce, sell the stoves and cook with the stove. Further aspects to examine are:

• How is it received by the cook?
• What kinds of food can be made on the stove?
• Even though the stove is cheap, can people afford to buy it?
• To what extent are people willing to accept preparation of the biomass if necessary?

More info:

Per S. Nielsen, Department of Buildings & Energy,
Bldg. 118, Technical University of Denmark, 2800 Lyngby, Denmark.
Ph/fax:+45-4525-1949/ -45934430,
e-mail: psn@ibe.dtu.dk.

Photo text: The Peko Pe gasifier stove.

The figure illustrates the pyrolysis in the stove while burning grass. It shows the combustion 5-10 minutes after ignition where the upper part of the grass is burned. The grass is ignited from the top and placed vertical. The stove is made of 2 tins: an inner combustion chamber and an outer shell. The inner chamber (diameter 15cm, 20cm high) has diamater 0.8 cm air-holes in the bottom, in the middle and at the top.

• burns without smoke and CO emissions are low.
• is easy to ignite.
• is rapid in achieving boiling temperature, and it has a charcoal effect, when grass is used.
• is relatively cheap to produce.
• easy to move and carry around.

• metal, tools, skills are needed to produce the stove.
• biomass needs treatment which depends on the biomass source.
• it needs dry biomass.

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