Dr. Reddy - Understanding Stoves

Dr. N. Sai Bhaskar Reddy, CEO, GEO December, 2011

See the attached pdf (about 150kb): Understanding Stoves
it is an excellent brief summary that highlights the important aspects of stoves design and testing. e.g. fuels, fuel preparation, stove design, materials, use and testing.


What a wonderful review. There is a little bit in there for everyone. What sticks in my mind as a designer is the need for a very low biomass stove for cooking on the floor. If it is going to work well at that height, and not have a fan, it is going to have to be a cross draft stove with a chimney or short chimney. Perhaps we should be concentrating on that because if we find an acceptable answer, hundreds of millions will be adopted.


when one uses the word chimney in India, the general perception is that of a long tubular structure, meant for leading the smoke out of the house. It costs more than the stove itself, and therefore, it is generally rejected by stove designers. What you are refering to is most probably a shorter pipe, which would serve to create draft and not as a device to take the smoke out of the house. Interesting idea.

Dear Crispin,

Thanks a lot. In the two pot stoves, while the gases move towards the second pot, there is some length and time for gases for combustion. In the two pot stoves the draft of the flames is across before reaching the second pot. Importantly, for the single pot stoves, short chimney is a great idea. I agree with Dr. Karve the cost of chimney costs more than the stove.

The height of a average Indian women while sitting on the floor and cooking is about 2 to 2.5 feet (it will be even less when they bend in acute angle to reach the stove, as they cannot sit too close to the stove). It is almost inconvenient for them to cook on a stove along with the cooking vessel which reaches above 1.5 feet.

Similarly for institutional stoves, especially for the cooking needs of 200 for more and served at a time (schools / hotels / etc.) the height of the stove is a major concern. From the surface of the ground they will never let the height of the stove exceed 6 inches. I had to literally push the stove into the ground and create a ramp to meet the needs of the cook. Because for stirring and lifting the cooked food from fire, etc., are the difficult tasks. The utensil is usually dragged to the serving area.

Dr. N. Sai Bhaskar Reddy

Dear Xavier, Crispin, Rok, Krishna, Tom Miles and All,

Thank you.

>Xavier Brando: Yes, height is the major concern for institutional stoves, so I discovered also.

>Crispin: We found in Swaziland where people are not tall and the cooks are often
teenagers that access to the pots was important. The height of the stoves
that hold a 70 litre pot is not really reducible. Thus we build a step
beside each stove, at least two, from concrete blocks or recycled bricks. It
happens that stoves are often installed in pairs so the steps are usually
placed between them allowing access to both stoves.

The steps are important for accessibility. Recently I have prepared a kitchen and other spaces plan with some of the aspects including steps.

For institutional stoves facilitation stove design, kitchen and other spaces are also important. Sometimes facilitating a good stove for a new institutional kitchen is easier than for the existing institutions.

Especially in the government schools in Andhra Pradesh, 99% of biomass stoves in use are three stone stoves (Mid-day meals are served in the government schools as per the policy by Government of India). Three stone stoves require less space and these stones (stove) can be moved to any place as per the convenience. The roof of the kitchens in majority of the cases is very low. The percentage of cost spent on kitchen as compared to all the infrastructure cost in many institutions is less than 1%. In many schools there is no kitchen created yet (cooking is done in open places / under the trees). Most often there is no allocation of budget to create a good kitchen. The cost of a good stove and installation charges should be part of the kitchen. Stove, Kitchen and other spaces are integral part of facilitation of good stoves. To facilitate institutional stoves successfully, I had to look at the below aspects:

  • Space for stove: The efficient good stoves often consume more space than the traditional inefficient stoves. Apart from space for stoves, there should be enough space for the cooks to move around.
  • Space for keeping food ingredients (rice, salt, spices, oil, etc.): Within the kitchen for making curries, etc, some ingredients are required, which should be accessible and close to the stove.
  • Space for utensils / spoons, etc.: This space is rarely found in the kitchens.
  • Space for fuel wood within kitchen : There is need for space to keep the required amount of fire wood needed for cooking. The cooks don’t prefer to go out to get the fuel wood and they decide to keep all the needed fuel wood for one cooking period.
  • Ventilation (chimneys), cross ventilation (windows) : There are different types of spaces existing for cooking. A) Cooking under the trees (completely open) b) Cooking in semi-ventilated conditions - small 4 to 5 feet high walls cover the stoves and covered with a roof (thatched / tin / asbestos / etc.) c) Cooking in the rooms with one or two windows, with or without a ventilator / chimney / hood.
  • Food pre-preparation place: The cooks prepare the raw vegetables cutting them, clean rice and dal from small stones, etc. This place is very essential and should be located close to the place of cooking. It was found that due to intense heat from the cook stoves, they do all preparations as far as possible. If this place is close to the kitchen, there won’t be wastage of fuel and time.
  • Food items storage place: The rations are brought on monthly / fortnightly / weekly basis (as per the convenience). This storage room should be located close to the kitchen.
  • Location of the water: As water is an important requirement in cooking, the location of the source of water is important. If running water is available, a tube can be connected to bring water. Where running water is not available, a drum / bigger vessel is kept within the kitchen for storing and using the water. This water storage container within the kitchen adds to inconvenience for the cooks.
  • Utensils washing place: All the utensils, including the plates need to be washed, this often found close to the kitchen. If not properly designed leads to inconvenience, say the fuel wood might get wet with overflow of this water. It also leads to unhygienic conditions around the kitchen.
  • Waste management: The biomass collected from plates, wasted food, vegetable waste, etc., also requires a place to store before disposing. Compost bins are a good option, if space is available.
  • Serving place: In institutional kitchens the serving place should be close to the kitchen. The transportation of the cooked food is a major problem with distance, unless trolleys are available (it is very rare to find trolleys).
  • Hand wash place : A hands washing place (wash basins) to be located close to serving place for students. The same place is used for cleaning the plates and glasses before and after eating.
  • Drinking water: Place for drinking water should be close to the food serving area.
  • Bulk fuel wood storage place: The fuel wood is bought on weekly or monthly basis. There is a need for a waterproof place to store it.
  • Fuel wood preparation: Fuel wood bought is cut into small pieces of wood for convenience of cooking. Sometimes this work is done close to the kitchens. Sometimes they need to dry the wood in the sun, so requires some vacant open place too. This place is close to the kitchen. In the schools, sometimes the noise of cutting wood disturbs the students in the class rooms.
  • Collection and storage of ash and charcoal: This is a valuable resource. Many times it was found that the cooks sell the charcoal collected for other purposes. Some part of ash is used for cleaning utensils and some part is wasted. Ash, charcoal and the food waste can be used to make a very good biochar compost.
  • Access to the kitchen: The bullock cart / auto trolley / tractor / any other vehicle that brings the wood and rations to the kitchen, should have a good access path.
  • Aspect: The sun light is a very good source and could be used effectively for cooking. In parts of India, the SE corner is the best place for location of Kitchens. There will be plenty of sunlight (the tropic of cancer crosses almost middle of India), there will be more sunlight from the southern direction. During daytime cooking there will be advantage of the natural light too. It is convenient to dry the food items in the southern court yard, like chillies, dal, and flour, etc., (for keeping the food items fresh and away from insects) which is a close place near the stove.
  • Prevailing wind directions: The prevailing wind directions in parts of India are mainly from southwest. By locating the stove (facing east) in a southeast corner of the kitchen, would help one also avoid smoke. And the wind will be in the draft direction of the stove, supporting efficient combustion.

(Note: In India, people have traditional beliefs (Vaastu), that is kitchen should be located in the south east corner in a building. Which can also be understood scientifically (Aspect / wind directions). Sometimes people don’t cook if the kitchen is not located as per Vaastu.)

> C V Krishna : ..Apart from the excellent cascading of the needs for understanding the stove, I feel this funda of yours in simple language will serve us to teach the school students above standard VI.

>Tom Miles: This is an excellent idea. In the committees of the Global Alliance for Clean Cookstoves we discussed and recommended educating bureaucrats but it would be far more effective to educate students about stoves.

Yes, educating and creating mass awareness among students is important. It is strange that in the text books of schools / universities, there is no mention of the word “STOVE”. We have regular programs in the schools for awareness on stoves https://picasaweb.google.com/saibhaskar.gsbc/AwarenessToChildren . As well facilitating institutional stoves as part of the project Good Stoves and Biochar Communities Project, supported by GoodPlanet.org.

Dr. N. Sai Bhaskar Reddy