21 Jan The Mewar Angithi: A $1 Device that Transforms a Traditional Chula into a High Efficiency Cook Stove
Fig. 1. A Traditional “Angithi” stove that works with coal, charcoal or even candles for heating
The controlled use of fire, and more specifically cooking, is a fundamentally human creation that has allowed us to become who we are, an ingenious tool-wielding species that dominates over all other species on Earth. And yet, our infatuation with fire, and specifically cooking, is projected to be the central reason for our ecological Icarian downfall in the near future, unless we take remedial action soon. Not only is our penchant for eating cooked animal foods, such as meat, causing us to devour the biosphere unsustainably, the main method of cooking using firewood employed by 3 billion humans worldwide, is devastating to the last standing forests of the world in India, Africa and Latin America.
Firewood burning is the second most significant quantitative reason for deforestation worldwide, next only to livestock production. The soot from incomplete combustion of firewood is also a potent greenhouse gas. As it gets deposited on the ice in the Arctic through wind currents in the Northern hemisphere, the black soot also absorbs solar energy whereas the original ice would have reflected it. As such, the Arctic region is heating up faster than almost every other part of the Earth due to climate change. Since the industrial chemicals that we have emitted into the atmosphere come down in the rain, get absorbed by trees and get embedded in the trunks and branches of trees worldwide, firewood smoke has also become a potent human health hazard, contributing to a loss of as much as eight years in life span for the women who cook with firewood. That is the level of lifespan reduction that can be expected from smoking the equivalent of two packs of cigarettes each day!
Much effort has been expended to mitigate the effects of firewood use among the 3 billion, but almost all of these efforts have been largely unsuccessful. The Global Alliance for Clean Cookstoves (GACC) has an ambitious plan to deploy 100 million High Efficiency Cookstoves (HECs) by the year 2020, but the plan has not yet been put into action due to technological and process hurdles. The Government of India has been trying to deploy HECs in the rural areas of India for the past two decades, but this intervention has been largely unsuccessful as well. At Climate Healers, we tried deploying solar cookstoves in the villages of Rajasthan and Orissa in 2010 and this was also unsuccessful. Since then, we have been working with universities worldwide and mainly with Prof. Uday Kumar’s team at the University of Iowa on a stored energy solar cook stove that can address the primary reasons for our unsuccessful deployment in 2010. But progress on this project has been slow due to technical difficulties under our low-cost constraint. Meanwhile, the carbon offset mechanisms that Climate Healers planned to use for funding the deployment of these stored energy solar cookstoves have become mired in controversy and are largely defunct. Therefore, as of late 2014, we were open to consider a new course to get over these considerable procedural and technological hurdles.
Over the past three weeks, Prof. Uday Kumar, Prof. Matthew Hill and other members of a multidisciplinary research team from the University of Iowa, along with thirteen students from the University of Iowa Winterim program, Michele Del Viscio, a mechanical engineer and Climate Healers volunteer from Italy, Pratiti Priyadarshini and Paras Charan from the Foundation for Ecological Security (FES), have been working alongside us to understand the reasons for the poor uptake of HECs in the villages of Rajasthan, India. The team conducted careful observations of the cooking process as the women of Karech and Gogunda tried to use two of the top-selling HECs in the world, labelled A and B. And through the gracious assistance of these wonderful women and the interpreters who helped us communicate with them, the main reasons for the poor uptake of these stoves in the villages of Rajasthan became quite clear to us. Here they are:
1. The commercial HECs don’t accommodate the wide variety of wood fuel types that are available in Rajasthan. For instance, the HECs can’t accept large pieces of wood without having them split lengthwise, which is very difficult for the women to do. When they face such a hurdle, the women tend to abandon these HECs since their traditional “chulas” (mud and brick stove) have no such size limitation.
2. HEC Stove A heated the clay “tawa” (a vessel for cooking rotis) too much in the center and not enough at the edges with the result that the women had to constantly rotate the rotis (flatbreads), especially the corn rotis, in order to cook their meal. Perhaps as a result, Stove A was not nearly as efficient in its use of firewood for cooking as advertised.
3. The mouth of HEC Stove B was too large to fit the clay tawas used in Rajasthan, with the result that we had to jerry-rig a grill to hold the clay tawa in place. Perhaps as a result, much of the advertised efficiency of HEC Stove B could not be obtained as well.
4. Though there was some savings in firewood use with the HECs, the women estimated the stoves were worth as little as one-fifth the actual retail price of the HECs. Even then, it appeared doubtful that the women would actually cough up that reduced capital amount to acquire such HEC stoves.
The University of Iowa research team is now preparing a more detailed feedback for the HEC stove manufacturers, including many user interface issues that the women found.
Traditional chulas vary in size and shape to accommodate the different types of cooking vessels and foods cooked in them across the world. Our experience in Rajasthan showed that a single HEC stove cannot possibly replace all these traditional stoves. Rather, significant fuelwood reductions can only be achieved with locally customizable solutions in different parts of the world.
Meanwhile, it also became apparent to us that the low smoke effluence and main savings in firewood use of the HECs was due to the engineered airflow from below the fuel source in these HECs. Without such engineered airflow, the traditional chula tends to accumulate embers that pile up and emit soot as they burn inefficiently due to a lack of oxygen. But such engineered airflow is precisely what a traditional coal “Angithi” stove does as well (please see Figure 1). An Angithi stove has a large opening for airflow below the flame and a grill above which the fuel source such as coal or charcoal is placed. As the fuel burns, it creates a low pressure zone and air rushes through the inlet below to fill the void thus supplying fresh oxygen for the continued burning of the fuel. This airflow mechanism of the traditional Angithi stove is found in both the HEC stoves that we tested in Rajasthan.
Figure 2. Engineering the “Mewar Angithi” for the traditional chulas of Udaipur, Rajasthan, India.
Enter the “Mewar Angithi”, a simple metal device that we engineered to be placed in a traditional chula in order to provide the same airflow mechanism the traditional Angithi stove as well as the HEC stoves. For the chulas found in the Mewar region of Rajasthan, this metal device can be constructed using a trapezoidal bottom metal plate which can then be welded onto a bent top metal plate with air holes in it. The top metal plate can be engineered by bending a square piece of porous metal into a trapezoidal shape with trapezoidal sides (please see Figure 2). The resulting insert has a sloped bottom plate so that any ash collected on it can slide down to the exterior. The fuelwood is placed on the top porous plate and as a result of the airflow from below the fuel source, any embers that break off from the wood would also burn up completely. (Please see Figure 3. In the engineering prototype, we used a square bottom metal plate that we also bent into a trapezoidal shape and punched holes in the side of the bent bottom plate so that the top and bottom plates and be held together with metal wires instead of being welded together.)
Figure 3. Using the Mewar Angithi in a traditional chula of Udaipur, Rajasthan, India.
We found a porous Mild Steel (MS) metal sheet in the local market in Udaipur, Rajasthan, as scrap metal from the metal washer industry. As metal washers constructed for use, e.g. in the automobile industry, are punched out by machines from a large sheet of metal, sufficient space between these holes have to be provided in order to prevent the force of the punching machines from bending the sheet and thereby distorting the washers. Such scrap metal sheets are ideal for constructing the Mewar Angithi and can be purchased in local markets at one-fourth the cost of solid metal sheets.
We estimate the Mewar Angithi can be fabricated locally at a cost of less than one dollar per piece. And in preliminary tests involving the cooking of corn rotis and vegetable sabzi (curry), the Mewar Angithi achieved low smoke effluence (as estimated qualitatively by the users) comparable to both the commercial HECs, while providing around 60% reduction in firewood use (as measured quantitatively by the research team), which is precisely the advertised maximum savings of both these HECs. In addition, the Mewar Angithi can be easily reshaped and customized in different regions of the world to fit the sizes and shapes of the traditional stoves used in these regions. Thus, the Mewar Angithi promises to be an easily malleable solution for the HEC stove deployment problem that has been vexing the world’s policymakers to date.