To experiment with the traditional chulha in a controlled setting, the team decided to build a makeshift chulha in the backyard of our hotel in Udaipur, Rajasthan. Though our makeshift chulha was going to be made with bricks and would not have mud caked around it as the traditional version in the villages, we felt that having a controlled setting would be useful for making comparisons. Once that chulha was built, I was tasked with starting the fire.
Perhaps the ground under the chulha was wet, or perhaps the firewood was wet, but for the life of me, I couldn’t start the fire no matter how I arranged the sticks! Then I turned to Michele and asked him to light the fire.
Michele is one of the most practical engineers that I have ever encountered in my life. Throughout that Winterim, I was constantly amazed at how he could take whatever was lying around and use it to solve any knotty problem that we faced, whether it was HEC-B’s mouth being too big, or whether we couldn’t latch a gate in the village. But I was pleased to see that initially, even Michele couldn’t start the fire in that makeshift chulha! Then, true to his reputation, Michele just walked around the backyard, picked out a grate from one of the unused HECs, stuck it in the chulha and lit the fire. Now the fire started almost instantly!
We eventually abandoned this experimental setup, since we were able to get the same user to work with all different stove configurations to cook their standard meals. But the fact that Michele used a metal grate to start the fire in that chulha stuck in my head. This was the first “Aha” moment.
Then, as were compiling a list of the problems that the women were experiencing with the HECs, we were struck by the fact that the traditional chulha had none of those problems. The only problem in the traditional chulha was that the airflow worsened over time due to the embers piling up. To address the airflow issue, we were bouncing around various engineering solutions - such as creating a grate on the floor of the chulha with a chamber underneath that would collect the ash, which we imagined connecting to an air duct from outside the house. Then the anthropologist among us, Matt, put his foot down firmly. He said that we must not even think about changing the traditional chulha in any way! The best we can do is to devise an accessory that the women can take away at any point to return to their old way of doing things.
That was the second “Aha” moment! That’s when the idea of adding a grate to the traditional chulha flashed. A traditional stove burns with good thermal efficiency at the start of the cooking session, but the efficiency deteriorates over time. Typically, this efficiency starts at 15 percent and reduces down to 5%. However the grate that Michele had used to start the fire in the makeshift chulha was clearly not going to be of much use. It was designed for one of the HECs and its openings were large enough to allow the embers to fall down and pile up underneath it. The HEC itself had a secondary grate to drain the ash in the form of holes on its bottom plate, in addition to this coarse grate. Therefore, we fashioned a special raised metal grate that had holes to drain the ash and made sure the holes were too small for the embers to fall through. We had the design fabricated in the marketplace in Udaipur, took it to Lassibai’s home in Karech and asked her to test it out in her traditional chulha.
Lassibai examined the grate and she was clearly not impressed with it. But she was game and inserted it in the chulha before she started her cooking session. Typically, when she starts, Lassibai brings a stack of wood from her pile in the back and keeps it near her. Based on her years of experience, she brings precisely the amount of wood she needs for her meal, almost to the stick. But this time, after finishing her cooking, she looked back and was amazed that more than half the stack that she had brought was still lying unused! So were we amazed, as well!
In fact, for the same meal, Lassibai had used 2.9 kgs of wood in the traditional chulha without the grate, 1.8 kgs with HECs A and B, and 1.1 kgs in the traditional chulha with the grate. That simple grate had caused a 60% reduction in wood use in the traditional chulha itself! I couldn’t believe my eyes, but since we were at the end of the Winterim, we couldn’t test the grate much further during that trip. Therefore, I made arrangements with my brother-in-law, Vasanth Kukillaya, who’s a metal working expert, to engineer a robust version of the grate and have it tested at an official cookstove-testing center that is certified by the Government of India. We called this grate, the Mewar Angithi (MA), since this Angithi (a Hindi word for grate) was discovered in the Mewar district of Rajasthan.
It took about 3 months for the process to complete since we had to do paper work for the Cookstove Testing Center, schedule a date, and then Vasanth had to travel to Udaipur with two samples of the device to get it tested. After the first day of testing, Vasanth called me to say that Prof. Panwar and Prof. Rathore from the Maharana Pratap University affiliated with the Cookstove Testing Center were very animated at the end of the test and wanted to repeat it again the next day. Once the test was repeated, the Center released the official results: 63% reduction in wood use and 89% reduction in particulate matter (PM 2.5 μm) emissions for the same delivered energy! As soon as I got those official results, we set the ball rolling on field deployments and extensive testing in real world settings.