Improved Cook Stove

June 30, 2009

Dr. Krishna Raj Shrestha

1. Introduction

A cooking stove is a device in which fuel is burnt to cook food. It is usually located in kitchen. Besides cooking food, a stove is also used for heating the room, drying of certain items and agro-processing activities (AEPC, 2000).Improved cooking stove is a device that is designed to consume less fuel and save cooking time, convenient in cooking process and creates smokeless environment in the kitchen but the traditional ‘Chulo’ can’t do the mentioned function efficiently.

1.1 Design Features

The design of an Improved Cook Stove (ICS) involves the application of heat transfer, combustion and fluid flow principles in order to attain complete combustion of the fuel with a minimum amount of excess air, maximum transfer of heat from the flame and the flue gases to the cooking vessel, and a minimum loss of heat to the surroundings. The stove consists in principle of a combustion chamber, pot holder and baffle depending upon the type of stove and chimney.

Combustion Chamber:

In the household cooking stove, the combustion chamber is made of clay or brick mixed with chipped rice straw/agriresidue with a diameter of 20cm. and height of 14 to 19cm. respectively. A metal grate is placed at the bottom of the combustion chamber and about 10cm. height from the base. The aperture in grate for the passage of air is approximately 30 per cent of total grate area. Below the grate, there are two 6 sq. cm. second air holes on opposite sides for better mixing of air in the combust chamber. The fuelwood supply door is 12 x 15 sq. cm.

In the Institutional cooking stove , the cooking pot is sink into the combustion chamber and is made of brick and clay mixed with agri-residues with a diameter of 6 cm. and height of 26 cm. respectively. A metal grate is placed at the bottom of the combust chamber and about 20 cm. height from the base. The aperture in grate for the passage of air is approximately 40 per cent of total grate area. below the grate there are two 12 cm. diameter secondary air holes on opposite sides for better mixing of air in the combustion chamber. The fuelwood supply door is 20 cm. x 40 cm.


In household cooking stove, the potholder is modified like an inverted come shape to fit the size of the pots used locally with pot supports in accommodate local pots. The diameter of the potholder is from 20 cm. to 35 cm. or more.

The critical point in the design is a gap between the walls of the pot and pot support. The exhaust outlet gap was made 1cm. when the gap is large heat is easily lost through the outlet gap by the flame and exhaust gas convection. With the small gap, the flame from burning firewood has a better contact with the pot side wall before exist to the atmosphere.


In two pot ring stove, there is a baffle in the second pot ring. The baffle is projected from the fuel tunnel to the centre of the second pot ring. The gap between the pot sit and the baffle should be 4-5 cm. The function of the baffle is to divert the flame and hot air directly towards the bottom of the pot.


In wood burning ICSs, sufficient air has to be provided in order to achieve complete combustion. This is accomplished by providing sufficient air openings in the fire-box of naturally aspirating stoves. However, in multi-pot stoves, even with a large opening an additional positive suction head is required to overcome the resistance offered by the flue passages. This is accomplished by providing a chimney, which creates suction at the top as a result of the temperature difference between the hot gases at the base of the chimney and the ambient air. As a result, flue gases are drawn from the stove and air is induced into the cook stove. A chimney should be designed in accordance with the rate of flow of the flue gases, hence upon the output of the fire in the stoves. Too strong a draft may draw in excess air which dilutes the heat of combustion gases. Draft increases with the height and the diameter of the chimney.

1.2  Stove Testing

A large number of variables were taken into account for a truly comparable study in the laboratory as well as in the field to some extent. The tests designed here revealed qualitative and quantitative information about the improved stove performance as follows:

–         the thermal efficiency or percentage heat utilized (PHU) for boiling certain amount of water ie. high on low power phase.

–         the amount of fuel required to cook a given quantity of f

–         the range of power output

–         the case of operation

–         level of pollution

–         maintenance requirements

–         life time

Water boiling test:

A standard pot diameter was used and filled with 2/3 water the initial temperature of water was controlled as far as possible throughout the tests. A fixed amount of kindling was used for ignition. Then the pot with a lid was placed on the stove and the time was immediately recorded. The temperature of the water in the pot was measured every few minutes until the water started to boil Time required to bring the water from its initial state to the state of boiling was noted. When the water started to boil, the lid was removed and then followed by lower power phase in which the output from the fire and reduced to the lowest level needed to keep the water within 2oC of boiling for a further 15 minutes. After 15 minutes, any water remaining in the pot was reweighed as with any remaining fuel. The amount of water evaporated, the weight of the charcoal left in the test was then calculated (RFD 1984).

For two pots, when the water in the first pot started to boil, the lid was removed and this pot was placed on the second pot ring and then followed again with full power until boiling.

The stove efficiency was calculated from the data gathered in the procedure discussed above. The percentage of heat utilization is the actual energy transferred from potential energy stored in the fuel to the water in the pot. Simply, it is the ratio of the energy output to the energy in put for a specific operation. The percent of Heat Utilization (PHU) for the test conducted here were computed from:

PHU=[(Mw Cp (Tb-Ti) + Me.L)/(Mf. B)] x 100

Where, PHU = percent of Heat Utilization (Thermal efficiency)

Mw = Initial mass of water (kg).

Cp = Specific heat of water (kJ/kg. k)

Ti = Initial temperature of water (oC)

Me = Mass of evaporated water (kg)

L= Latent heat of evaporation of water (kJ/kg).

Mf= Total mass of fuel used in the test (kg).

B= Lower calorific value of fuel (kJ/kg).

In calculating the efficiency, the following numerical values were used.

C= 4.2 kJ/kg. k

L= 2260 kJ/kg.

B= 16750 kJ/kg. Air dried, In case of low quality fuelwood

15500 kJ/kg. was used in the field.

13600kJ/kg.- Dung stick

13000 kJ/kg. – Agri-residue.

Power Output:

The power output is the amount of energy released from the fuel in a given time. The average power output is the average high power phase and low power phase. The power output of the stove is inferred from the tests by:

Mf    b



Where, P= Power output of the fire (kW)

Mf= Fuel consumed during the test (kg)

T= Time interval (sec.)

b= Lower calorific value of fuel (kJS/kg.)

Controlled Cooking Test:

Standard diameter pot was used. The quantities of fuel, food and water was measured. The cook did cooking in the usual manner and decided when the food was cooked . Cooking time and any relevant observations were recorded. The charcoal , remaining wood and the food cooked were weighed. The specific consumption were calculated by computing from:


Sc= —–


Where, Sc= Specific  fuel consumption

Mf= Fuel consumption during the test (kg).

Fe= Total Food Cooked (kg)

2. Present Energy Scenario

In Nepal average annual population growth rate is 2.24 percent and more than 85 percent of the population live in the rural areas. The traditional energy accounts for 86.2 percent and the share of commercial energy is 13.8 percent of the total energy expenditure in 2000/01. About 76.6 percent of Nepal’s total energy comes from fuel wood, 3.8 percent from agricultural residues and 5.8 percent from animal waste while fossil fuels accounts for only 13.8 percent (petroleum 9.3, coal 3.1 and electricity 1.4 percent). About 89.3 percent of the total energy is used in domestic sector in which more than 90 percent is used for cooking purposes, 4.6 percent in industrial sector, 1.1 percent in trade sector, 3.9  in transport sector and agriculture sector accounts for 0.9 percent (Economic Survey, 2002). The total energy consumption of the country is 315 million GJ in the year 1998 (WECS,1998), the average per capita energy consumption is 14.6 GJ in 2001 and the overall energy demand is increasing by 3 percent on an average per annum (MOPE, 2002). Annually about 11 million tons of fuel wood are burnt for cooking alone and even with the low performance (11 percent fuel savings) estimates indicates that one ICS can save on average one metric ton of fuel wood annually (WECS, 1996).  During last five years, about 52,300 ICS have been installed in various parts of the country and the percentage of the rural households using ICS is still less than 10 percent according to NLSS data. In the rural Terai and for hills areas, dried dung and agricultural residues have become an important alternative to fuel wood for coking and space heating. In the middle hills and in most mountain areas, wood and agricultural residues are the most common source of energy. In some remote high mountain areas there is either man-made (over logging or over grazing) or natural ( at the highest altitudes) fuel wood deficit.

3. History of  ICS in Nepal

The history of ICS programmes in Nepal dates back to early 1950s with the introduction of Indian models ‘Hyderabad and Magan stoves. The Agricultural Engineering workshop of the Department of Agriculture developed mould with which even unskilled persons could make ICS. This approach of self-construction of ICS with mould was extended as part of village development services of the “Tribhuvan Gram Bikash Karyakram” which ended in the early 1960s. Thereafter efforts continued in the mid 1970’s by the Women’s Training Centre in disseminating the Lorena Stove with further complementary efforts in its research and development work done by RECAST, Tribhuvan University.

During the 1980s interest and efforts were revived when the National Planning Commission included ICS in an attempt to address the pressing fuelwood problem. The government’s concern for fuelwood conservation was also reflected with the inclusion of ICS dissemination efforts as an important component of FAO assisted Community Forestry Development Project (CFDP) in 1981.

This effort was further complimented with the ICS field testing and design modification by RECAST in 1982. Consequently Ceramic Insert and Double Wall Stove replaced Lorena stoves.

During 1985 with support from UNICEF the ceramic stove and “new Nepali chulo” were distributed through the small farmers development projects of Agricultural Development Bank (ADB/N) and through the Production Credit for Rural Women (PCRW) programme of the Women’s Development Division (WDD).

The Terai Community Forestry Project (TCFP). Nepal Australian Forestry Project, Save the Children US, United Mission to Nepal, Resource Conservation and Utilization Projects (RCUP), CARE /Nepal have been the other major organizations and projects which took up further ICS dissemination efforts with varying degree of success. CFDP made a relatively larger effort in promotion and distribution of ceramic ICS in about 12 districts of Central Development Region. However, it stopped the ICS component in 1990. Although CFDP stopped from ICS dissemination, various other NGOs and INGOs continued Ceramic Stoves dissemination. All these efforts however, could not produce significant results due to number of problems including durability of insert stoves, lack of ICS skill training’s and lack of proper assessment of the needs and cultural preferences of different ethnic groups and geographical regions of the country.

4. Present Status of ICS in Nepal

Improved Cooking stove programme have been promoted in rural communities of Nepal since 1950s. Consequently, up to now more than 95,000 ICS have been distributed or installed at various districts in the country. Out of this about 57,000 ICS were distributed by the community Forest Development Projects, (CFDP) (Hills and Terai). It was during late 1980s that the large scale of ICS promotion and distribution took place in the country. Apart from CFDP there are other organizations involved in the promotion of ICS. These institutions together promoted about 40,000 stoves in Nepal.

Inspite of the discontinuation by CFDP, a leading Government Organisation, from large scale promotion of ICS new initiatives and efforts were underway since early 1990s from the various NGOs and INGOs with ICS as an integral part of their overall programme. RECAST developed a new model of stove known as improved Tamang stove which could be built completely from cheap readily available local materials. Furthermore, private sector NGOs like CRT/N took initiative in training and skill transfer to many NGOs, INGOs and local promoters.

5. Impacts of ICS programme

In spite of limited success in ICS dissemination of various designs in the past, it has been realized that ICS has many advantages provided technical qualities are maintained and socio-cultural needs of the diverse communities are met.

There are only few impact assessment studies undertaken to measure the extensive implications of the ICS program. Moreover, the paramount feature of all the organizations involved in ICS program related organizations are the lack of baseline studies. CRT/N with the support from ESAP prepared an “Inventory and Assessment of Improved cooking Stove Activities in Nepal” (CRT/N, 1999). The report is based on the profiles of the organizations involved in the promotion of ICS activities. The organizations engaged in the promotion and dissemination of ICS has revealed that ICS program has been able to yield wide range of benefit, which includes:

Saving in fuelwood and collection time.

Increased awareness among women on health aspects kitchen management and home environment.

Confidence building    on promoters and users.

Entrepreneurs developed at local level with additional source of income and ICS activity developed as a micro-enterprise.

Increased integration of ICS and more demand made by community in recent years have shown potential for gradual diffusion.

Apart from the above effects and impacts brought out by the promotion of ICS activities, promoted by various Organizations there are still bottlenecks cited by different organizations and that are not yet addressed and requires necessary corrective measures in the future. Some of them are listed below:

There is a lack of different appropriate models that caters the needs of different ethnic groups, socio-economic and physiographic conditions, which discourages continues use of ICS installed.

Innovative and flexible design do not either exist of there is information gap due to which there is low rate of diffusion and the benefit compared to cost investment is less.

Inadequate training and skill transfer, lack of monitoring and technical back up to the ICS promoters and installers at community level has contributed to defective construction and maintenance resulting poor performance and even risk hazards in some cases. This has been as a barrier to large-scale promotion and a challenge for ICS promoting institutions.

6. Future Plans

Over the years with the shift in the approaches and strategies from a top down, target oriented, subsidized approach to bottom up, demand driven and self construction approach is gradually coming up and many of the organizations have expressed their plans more in the qualitative forms rather than the quantitative ones. Thus from the organizational profiles of the ICS inventory, an attempt is made here to enlist the future plan of actions of all currently involved and potential ICS promoting organizations as:

Most institutions and organisations except few have shown their interest to promote ICS in the subsequent years. Many of the organizations have emphasised on users education, awareness campaign and training of local level promoters as part of their dissemination strategies.

Due attentions is being given to mobilise women’s participation in stove program.

Majority of the organisations involved in ICS promotion including NGOS is working with local level institutions or in partnership with other NGOS in some way or the other and they will be giving priority to strengthen these local partners in the implementation process.

Some organisation have incorporated technical follow-up support and monitoring mechanisms while others have planned for these crucial component for the success of the program.

Most the organisations seem to be concerned on sustainability of ICS program. So they ave planned to promote this on the need based participatory approach and integrating it along with other packages like social mobilisation income generating activities alternate energy and environment conservation and community development rather than implementing ICS program in isolation.

At present regardless of the type of stoves promoted, most of the organisations subsidise training either fully or partially. Some provide subsidy in kind for the stoves, except the UNDP supported parks and people project, which were implemented in the buffer zone of the Royal National Parks of Chitwan and Bardiya which has revised its subsidy framework where-in the users have to pay for even the training component. However the organization are silent on the subsidy issue which implies to assume that they will remain with the same existing approach.

7. Suggestion for Future ICS Policy

The tips of suggestion made by different organizations are summarized below:

ICS programme should be integrated with other socio-economic income generating, alternate energy, environment or health programme and should be based on felt needs.

More focus should be given on the R&D in order to develop appropriate designs to meet different requirements and due attention be given for kitchen improvement and management.

Transfer of skill should be at local level in order that an entrepreneurship be developed.

The training to the promoters if organized on regular basis would help in promoting ICS. Further, there should be monitoring, follow-up and feedback mechanism.

There should be a networking forum, which enables inter-actions and information sharing among stakeholders at different levels.

There should be consistency in subsidy policy to avoid confusion and the subsidy level should be gradually decreased.

ICS programme should be guided by and included in the Government policy.

The cost of the ICS should be within the reach of the beneficiaries e.g. Metal stoves are very expensive for low-income people of remote districts.

The promotional materials on ICS like pamphlets, booklets, handouts, brochures should be available in the program areas.

The ICS network should be strong and effective.

8. Lessons Learnt

Lessons learned by various organizations during the implementation of their ICS activities have been summarized here which would no doubt are the guidelines for any future ICS interventions.

Women should be actively involved as the key actor/partner in all phases of ICS development.

For the sustainability of ICS program, the ICS should be built by the users and assisted by ICS employed workers. This is necessary in order to maintain and repair stove regularly to ensure successful operation.

More research on the various models of ICS, efficiency improvement, use of locally available materials, stove design with flexibility in taking a range of fuelwood sizes, stove design according to the religious beliefs and cultural and social practices of the user groups has to be carried out.

The users should have sufficient orientation in the installation, operation and maintenance, and eliminating possible fire hazards of ICS.

The research institution engaged in R & D activities should be supported financially.

The ICS should be integrated with Kitchen Improvement and Management program. More over, ICS program should be integrated with other rural development activities, such as literacy program, public health program, saving and credit program, environmental awareness, women development programs.

The training on ICS should also deal with various ICS designs which should include variation due to the cooking habits, cultures, household numbers, household’s physical structure, seasons.

ICS promotion should give importance on improving health of women and children.

The metal stoves are beyond the reach of poor families due to its high initial cost especially in remote areas. Hence; the cost of ICS should be affordable to the beneficiaries.

The mud type of ICS has not been feasible in the cold high mountain areas.

Success of ICS has usually not been seen in very poor families due to their fooding habits and the excessive use of other low-grade biomass.

Promotion of cook stove has a very important role in the rural Nepalese context with poorly ventilated kitchens, poor sanitation, and drudgery women etc.

ICS review and feed back of the program has to be done from time to time.

Close and regular monitoring is very much essential for orientation/ continuity of ICS.

The promoters should be selected from various ethnic groups (from higher up to lower caste) There have been the cases that the lower caste promoters are usually not allowed to go inside the kitchen, So this needs to be taken consideration.

ICS should be promoted on users demand.

Local animators/motivators and ICS promoter are essential for the ICS dissemination. Local training capability must be build and be co-ordinated by local Level Organizations. so that she/he can be available if problems encountered.

Due to the food habits of Tamang, like eating local porridge “dhido” and preparing local alcohol “rakshi”, the present ICS model need to be modified to suit the needs of Tamang communities.

Before starting the project and fixing the target groups, baseline assessment is necessary and also socio-economic study should be carried out.

There should be proper co-ordination among different institutions for effective information sharing on ICS.

9. Conclusions

Alternative Energy Promotion Centre (AEPC) as a national lead organization in the renewable energy sector has a key role as a facilitating or catalytic organization for the promotion of RET activities in Nepal. Very little information regarding ICS was available from the Centre. Over the years there has been shift in the approaches from top down, target oriented, subsidized approach to bottom up, integrated, demand driven, self-construction approach. Many organizations have withdrawn the ICS activities whilst many new organizations have emerged as an active ICS promoter. The efforts of Governments and Semi-government Organization have been significantly reduced in the 90s as compared to 1980s while NGOs, CBOs INGOs and private organizations have increased their interest and involvement in ICS related activities integrating this into their ongoing programs. There is an urgent need for a strong ICS network forum, as felt by most of the organizations involved in the ICS promotion including the need for a promotional and informative materials catering to the need of different socio-economic diversities.

10 References:

1. AEPC, An introduction to Alternative Energy Technology in Nepal, Kathmandu, 2000.

2.  Economic survey, HMG/N 2001/2001.

3.  Shrestha, D.L., National energy Situation, WECS, 1999.

4.  MOPE, HMG/N state of Rural energy in the Mountains, Nepal, 2002.

5. RFD, Improved Biomass Cooking Stoves for Household Use. RFD,   Bangkok, Thailand,               1984.

6.  CRT/N, Inventory and Assessment of Improved Cooking Stove Activities in Nepal.                  CRT/N, 1999.


2 Responses to “Improved Cook Stove”

  1. John Taulo Says:

    Very useful info. send as much to email address

    John Taulo

  2. Dr. Krishna Raj Shrestha

    janata mohila kallayan sangstha is a women & child development org. some time ago giz advice for Improved Cook Stove emplemantation for mass people. but they have not help our org. my org. place country of bangladesh undevelopen area khulna dristrict. upazila- dakope, batiaghata & dumuria. this place is sidar & illa effected area. please visit this org & help oru org.

    with thanks

    sabitry edbor
    executive director
    janata mohila kallayan sangstha
    house no#168, road no#11
    sonadanga r/a, khulna, bangladesh,

    cell phone- 880-1918-482974

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