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Development of cooking-cum-heating stoves in the upland of North Vietnam by Tran Ngoc Dang


Table of Contents

Boiling Point
Front cover of Boiling Point issue 39
Issue 39 (1997) Using biomass residues for energy
ArticleDevelopment of cooking-cum-heating stoves in the upland of North Vietnam
AuthorTran Ngoc Dang


Développement des foyers pour la cuisson et le chauffage dans des fermes au Nord Vietnam

La disponibilité de combustible pour les besoins de cuisson et de chauffage pose problème. En saison froide qui dure de 3 à 4 mois, la température est inférieure a 10°C. Entre 1989 et 1993, Forest Science and Technology Application Centre (FSTAC) a introduit et diffusé plusieurs modèles de foyers améliorés cuisson/chauffage. Cet article évalue les différents modèles qui ont été introduits. Les résultats montrent que le taux d'utilisation est extrêmement élevé, les économies d'énergie sont de l'ordre de 30 à 50% alors que le gain de temps lors de la cuisson est de 16 à 32%. Cependant l'usage chauffage n'est pas satisfaisant. Le gain n'est que de 1 à 2°C par rapport au foyer ouvert.

[top] [end]Introduction

Fuel supply for daily cooking and space heating in winter in the upland of North Vietnam has become a problem. In the provinces under survey, Lan Son and Son La, where the average annual temperature is about 21 C, the cold season extends over 3-4 months, with the temperature often going down to 10C and occasionally to freezing point. The traditional open-fire methods of fuel burning still prevail, despite an acute shortage of fuels.

More rational methods and economic stoves are needed to save fuels, to reduce the pressure on forest resources, to improve the local environmental settings and, not least, to lighten the drudgery of women and children often involved in fuel and fuel-wood collection. (Figure 1).

The Forest Science and Technology Application Centre (FSTAC) has been working for years to improve cooking stoves and save fuels, in particular in the rural areas of this country, From 1989 to 1993, the first improved cooking stoves (the so-called BLN model) were introduced and disseminated in the lowland areas. In 1993, when dissemination reached the mountain areas, where the cold season is long and severe, two space-heating models, referred to as the BNLS models, were introduced.
Figure 1: Women carrying fuelwood (Mr Nghiep Tue Dang)
Figure 1: Women carrying fuelwood (Mr Nghiep Tue Dang)


[top] [end]The BLN model

The first improved cooking stoves (BLN stoves) were designed for the farmers' households for communities living in the deltas, the central areas and the lower mountain areas. In these areas a wide range of biomass fuels is available. There fuels include fuelwood, agricultural residues such as rice straw, tobacco and maize stalks and corn cobs and dried grasses, twigs and leaves.

The stove's performance, compared to the traditional open fire, was recorded as requiring 30-50% less fuel and taking 15-30% less cooking time. It is much more convenient for its users, producing less dust and lower temperatures in the kitchen, especially during the summer. It provided considerable protection against fire hazards.

[top] [end]The BLNS1 model

This stove was purposely designed to serve farmers living in the mountain areas. It is based on the BLN model, but a new feature is added; that of providing space heating for stove users, when required. The design differs from the BLN model in the following respects:
  • its size and weight have been reduced by 20-25% for use in houses built on stilts in the mountain area,
  • it has thinner walls than the BLN stove
  • the fuel-feeding opening has been enlarged by 15-25%
  • shaped, sloping pot-hole brims have been introduced to match the shape of the cooking pots
  • its curved walls improve the radiation of heat towards people sitting in front of it
  • it has ports at both ends to provide heat to others sitting by the fire
Figure 2: The cooking-cum-heating BNLS1 stove (Mr Nghiep Tue Dang)
Figure 2: The cooking-cum-heating BNLS1 stove (Mr Nghiep Tue Dang)


When heating is not required, one can close the ports at both ends of the stove and reduce the width of the fuel-feeding opening.

To improve the heating output, when cooking is not required, all but one of the pot holes can be covered with lids. A flue outlet is put over the additional pot hole which causes the heat to spread out to the fuel-feeding opening and the two other ports at the end of the stove (see Figure 3).

Figure 3: Schematic drawing of BNLS1 stove (Mr Nghiep Tue Dang)
Figure 3: Schematic drawing of BNLS1 stove (Mr Nghiep Tue Dang)


[top] [end]The cooking-cum-heating stove with bed heating device (BLNS2 stove)

This model is similar to the hlji kang (heated brick) bed of China which uses the heat from the cooking stove to heat a brick bed in winter.

[top] [end]Technology extension

The FSTAC introduced 220 BLNS1 stoves into two districts in two provinces of the mountain area of North Vietnam.

In January 1997, the FSTAC recorded the results in Table 1.

Table 1: Stove performance results for BLNS1 stove.
Number of stoves built Number still in use % still in use Comments
District 1 110 110 100 A few minor defects: Four reported star-like cracks at fuel-feeding opening and around pot holes
District 2 110 109 99 One destroyed in kitchen collapse. Five reported similar defects to District 1

[top] [end]Evaluation

All the stoves run successfully on all kinds of fuelwood, forest and agricultural residues.

The heated beds have not been widely used. The percentage in use is of the order 10-12% and is believed to be due to the shortage of available fuel. Most farmers would prefer the available fuel to be used only to fuel the stoves and thus warm the whole family.

Compared with an open fire, the BLNS1 stove reported similar improvements to those achieved by the BLN stove. These were 30-50% for fuel saving, and 16-32% for cooking time.

The room temperature is only fractionally reduced (1-2°C) compared to that obtained using an open fire.

From the table above, it can be seen that a good level of acceptance for these stoves has been achieved and the communities are expecting more BLNS1 stoves to be disseminated.

[top] [end]Contents: Boiling Point 39: Using biomass residues for energy

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Using biomass residues for energy - Briquetting agricultural residues - Briquetting of biomass residues in India using a Beehive Pyrolyser and briquetting machine - Briquettes in Sudan - An introduction to the reality of household fuel needs in Bangladesh - Sawdust utilization - experiences in Mutare, Zimbabwe - Biomass resources use in tea plantations in Sri Lanka - Development of cooking-cum-heating stoves in the upland of North Vietnam - Fuelwood as a source of urban household energy in Ethiopia - A supply perspective - Community-managed micro-hydro projects in Northern Pakistan - The low wattage cooker - the Nepal experience - Routes for commercialization of rural stoves - Thermally efficient improved wood-burning metal cooking stove - The Women and Energy Project for stove dissemination in Kenya - crossing the sustainability bridge

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