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close this book Boiling Point No. 32 - January 1994
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View the document The Fuelwood Issue Restated
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Heat-storage Cookers in Nepal

- who will Benefit?

by Andrew Scott, ITDG.

With the increase in the installation of microhydro schemes in rural Nepal, there has been a growing interest in very low power consumption domestic cooking stoves (250W) to make fuller use of the electricity now available. Because of the pressure on the diminishing sources of firewood, domestic cooking seems an ideal use for this alternative energy source.

ITDG started research and development work on low-cost heat storage cookers in 1982, and now has a tested, prototype air heat-storage cooker (AHSC) in which air is blown continuously over a 250W resistance heating element, and through a heat store of small stones. For cooking, the hot air is directed to the boiling and simmering rings on which the pots sit. Air temperatures of over 300C are maintained, enabling water to be boiled at the rate of one litre every 10 to 15 minutes.

Unfortunately, the AHSC is still a long way from meeting the requirements of the poor, rural households which the programme aims to benefit; much has been learned, but much remains to be done.

An affordable technology?

Before a household can consider buying an AHSC, it must be able to meet the following criteria: there must be an electricity connection with a capacity of 250W or more; the supply must be continuous over 24 hours, and there must be a flat tariff (uniform cost for kWh). The family must be able to afford the price of the cooker, plus the monthly electricity charge. Fewer than 10 per cent of households in Nepal have an electricity connection, and most are in urban areas, connected to supplies from the Nepal Electricity Authority which does not charge a flat tariff.

In its present design, the AHSC is only large enough for households of up to five adults. The average Nepali household size varies between 5.38 and 5.85 people, and an estimated two-thirds of rural households have five or more persons.

Households with connection capacities of over 250W are in the middle-to-upper income group. The average annual income of a rural, middleincome household is estimated to be Rs.14250 (200); while upper-income households make about Rs.18000 (260), although less than half is earned in cash. The investment of Rs.4000 in an AHSC would be equivalent, therefore, to 5() to 60 per cent of the total annual cash income of a middle-income rural household.

The AHSC can reduce fuelwood consumption (per household) by at least half. This would save some people money, although the question remains: how would this benefit the rural poor? Those saving money would be the middle-toupper income groups - who are connected to the electricity supply over 250W - this would have a knock-on effect of depriving the lower-income households of money, because it is these households who collect firewood for sale.

While project work in Nepal is still being carried out to evaluate exactly how effective the heat-storage cooker is (in terms of its benefits to the rural poor), further developments have been made. There is now a heat-storage cooker which can be produced locally using locally manufactured components, for which a design manual has been produced. Further research is required, however, to develop low-cost cooking devices suitable for smaller connections, such as electric water heaters, as well as to assess the appropriateness of the existing stove designs in terms of their wider use, the technical support needed, and suitable training facilities.

For further details see 'Heat-storage technology for cooking' a report by ITDG and Dulas Engineering, March 1993 also Boiling Point, Numbers 25, 27, and 29.