In rural households, food is generally cooked on clay stoves called ‘chulhas’. Chulhas use biomass as fuel. A family of 5 to 6 persons requires about 8 kg fuel every day. Surveys show that, on an average, the domestic fuel consists mainly of agricultural residues and cattle dung, supplemented by wood to the extent of about 40%. Even families who can afford modern fuels, prefer to use biomass because it is available free of cost. In forested regions, where the inhabitants are mainly aborigines, the fuel consists almost exclusively of wood.
However, these traditional chulhas are very wasteful – they use only 10% of the total heating potential of the fuel burnt in them. A more serious disadvantage of the traditional chulhas is that they produce a lot of smoke, soot and unburnt volatile organic matter, which not only blacken the pots and the walls of the kitchen, but also lead to Indoor Air Pollution (IAP). IAP is one of the leading, and yet often neglected, causes of deaths in the developing world. It adversely affects the health of the rural householders by slow health degradation and setting the onset of killer respiratory diseases. In fact, several constituents of the flue gas condensate are even known to cause cancer. Housewives and infants are affected the most by these pollutants, because they are maximally exposed to the flue gases.
With a view to address this issue, ARTI has developed several popular models of improved cookstoves (briefly described below). These can be made of unburnt clay or cement concrete.
<!--[if !supportLists]-->1) <!--[endif]-->Laxmi: Of the total heat generated by the fuel, about 60% is available at the first pothole and 40% at the second pothole. Two dishes can be cooked simultaneously, and because the pots sit flush on the potholes, the flue gases do not escape into the kitchen but are taken out of the house via the chimney. However, the disadvantage of a two pot chulha is that a part of the heat is wasted if the second pothole is not used. Also, maintaining the chimney free from soot accumulation is essential for continued good performance. An improved version of this stove has also been developed – it offers higher efficiency owing to design modifications and an insulated body. It is also easier to maintain since it comes with a modular chimney.
<!--[if !supportLists]-->2) <!--[endif]-->Bhagyalaxmi: A chimneyless version of Laxmi
<!--[if !supportLists]-->3) <!--[endif]-->Grihalaxmi: Single pot chulha without a chimney. It is provided with a top grate which acts as a flame concentrator. A cast iron bottom grate is provided, just as in Laxmi and Bhagyalaxmi.
<!--[if !supportLists]-->4) <!--[endif]-->Parwati: Two pot chulhas with chimney. In this model, about 80% of the total heat is delivered to the first pothole and only 20% at the second pothole. As a result, only the first pothole need be used for cooking while the second pothole serves only to keep the food warm.
ARTI has also developed metallic body, portable stoves that run on woody/dry biomass. Based on the principle of gasification, these stoves are clean and efficient in operation, offering a steady blue flame. This makes them popular in rural as well as semi-urban areas.
<!--[if !supportLists]-->1) <!--[endif]-->Vivek: A portable metallic gasifier stove, Vivek requires sawdust or similar loose, powdery biomass as fuel, such as sawdust, dry grass, groundnut shells, threshing floor debris, etc. Charged with fuel, it can operate continuously for 1.5 to 2 hours. Gasification leads to blue flame and negligible level of emissions for the first 40 min of operation.
<!--[if !supportLists]-->2) <!--[endif]-->Sampada: This is also a portable metallic stove. However, unlike Vivek, it requires dry woody biomass as fuel such as wood chips, pellets, wood chunks, small dry wood twigs, wood shavings, etc. It is a low power stove, but well suited for light cooking tasks such as making tea, snacks, etc. The fuel is put into the fuel chamber and ignited from the top. More importantly, it also has a provision for adding additional fuel through a side opening for longer duration of continuous cooking. The special feature of this stove is that charcoal is left behind in the fuel holder after the stove operation. Thus, the stove not only delivers clean cooking but also produces a valuable bye-product in the form of charcoal.
<!--[if !supportLists]-->3) <!--[endif]-->Agni: Breaking away from the popular notion that cooking on a wood fire requires women to sit down, this is the standing model of a gasifier stove. Running on fuel of wood chips/briquettes, Agni gives intense heat and a high power flame, thus reducing the cooking time. There is substantial time saving in operations such as baking chapatis, shallow and deep frying, etc. Coupled with its advantage of the modern standing way of cooking, it is ideally suited for commercial cooking. Once filled, the fuel holder will give high heat for about 20-25 minutes (depending on the quality of the wood). Apart from having the facility to add more fuel for longer duration continuous operation, the stove also offers some flame control.
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