The improved kiln next to which potter Ramjubh bhai stands was the first to be constructed by the IIT Delhi RuTag team in Kachchh. Photo by Azera Parveen Rahman/Mongabay.

An air gap to save energy

The idea to make energy efficient kilns in Kachchh, said Ravi, was along the same lines as their work with the potters of Chhattisgarh and Maharashtra. They had to create insulation to reduce energy loss, but instead of asking the potters to get expensive insulation material, they decided to use the rat-trap bonding method.

“The rat-trap bonding method means that there is a gap between the innermost brick wall and the outermost wall. This air gap will create an insulation layer that is free of cost,” Ravi explained, “One of our Ph.D. students, Sunil Gokhale, suggested this, saying that in Western countries, many building structures are built this way.” The air gap in the kiln was three inches and so was the wall thickness on either side. Similarly, a gap was introduced between the lower brick floor of the kiln, where the wood is burnt and the ground on which it rests. These air gap insulation layers would minimise energy loss.

The improved kiln has helped potters in many ways. In addition to the advantages mentioned by Ramjubh bhai, such as reduced fuelwood consumption and time savings, there are further benefits. Ismaeel bhai, another skilled potter, noted a significant decrease in pot breakages. He emphasised that the pots are now baked uniformly, ensuring higher-quality output.

The rat-trap bonding method introduces an air gap between the bricks walls which acts as an insulation to minimise energy loss. Photo by Khamir, a local NGO.
The rat-trap bonding method introduces an air gap between the bricks walls which acts as an insulation to minimise energy loss. Photo by NGO Khamir.

However, there was a challenge — cracks started appearing on the wall of the kiln after the firing. Ramjubh bhai, who was involved in the making of the kiln, discussed the issue with Khamir and proposed that the alignment of the bricks be changed, “instead of keeping it standing on its narrow surface, lay the brick on its wider surface” to increase the strength. This reduced the air gap to two inches. “One of my students who was in Kachchh at that time called to ask me about this. The design will work as long as there is a one or two-inch air gap, so I gave the go-ahead,” Ravi said. Hence, for the rest of the 19 kilns that have been built in different villages in Kachchh till now, this tweaked design has been implemented.

“The rat-trap wall’s reduced thickness saves a lot of energy, but its structural strength is low because of which cracks can appear after firing. So we have asked potters to plaster the walls with clay if this happens,” Ravi said, “Meanwhile, we are working on sealing the wall with a steel belt to improve its strength.” The team is also in the process of experimenting with industrial-quality bricks that can tolerate higher temperatures.

In the meantime, Khamir is planning to build more than 20 such kilns in potters’ villages. “Our plan is to continue involving the potters in the construction so that they can learn the technique and replicate the design,” said Ghatit Laheru, the director of Khamir. Khamir will bear the production cost of such kilns, amounting to about Rs 30,000, while the potters contribute by making the kiln itself.

Saving energy means saving costs, time, and effort

One of the immediate impacts of saving energy is that the amount of firewood required to fire the kiln is less. “This would be of great help to us because unlike earlier when stems and branches of Gando baval (Prosopis juliflora) would be easily available, now access is becoming difficult,” said Sajid bhai, 24, a potter in Naliya, about 100 kilometres from Bhuj. In Kachchh, Prosopis juliflora, an invasive species is commonly spotted. However, according to Khamir, the charcoal industry, which clears large swathes of these groves for its use, is one of the reasons why access has become difficult. “We, our families, have to walk three or more kilometres to get these branches now,” Sajid bhai said.

Potter Sajid bhai stands next to the newly made improvised kiln in his house in Naliya in Kachchh. Photo by Azera Parveen Rahman/Mongabay India.
Potter Sajid bhai stands next to the newly made improved kiln in his house in Naliya in Kachchh. Photo by Azera Parveen Rahman/Mongabay.

Other than the struggle to access firewood, experts highlight another big concern. Ravi from IIT Delhi said that in Gujarat, waste material is often used to fire kilns because of the industries around. In urban areas, especially, Dipesh bhai of Khamir added that waste cloth and plastic are used to fire the kiln. “As you can imagine, the fumes that emanate from burning these materials are very harmful to health and the environment,” he said.

Potters using the improved kiln, they will be able to fire it more often and make more ware. Sajid bhai says that pottery work is mainly done only for four months in the year, which are the summer months. This is when the kiln is fired. This work stops in monsoons. For the rest of the year, they make enough stock of the finished product. He also said that with the improved kiln, he hopes to be able to fire his kiln more often and make more ware. “As of now, I fire my kiln two or three times a month. We make the clay pots in bulk and fire it together,” he said. He mostly sells his ware at fairs and in the local market.

Over the next few months, Ravi and his team also plan to conduct an energy audit of the improved kilns. “The potters are noticing a 40-50% reduction in fuel requirement, so there is 40-50% less carbon emission,” he said. These kilns are therefore not just helping the potters, they are benefitting the environment too.

A traditional, open-fired kiln used to bake the clay ware. Photo by Azera Parveen Rahman/Mongabay.


Banner image: An improved kiln is being built in Kachchh, Gujarat. With the new improved kiln, potters find the need for fuelwood significantly reduced. Photo by Khamir, a local NGO.

Article published by Kundan Pandey

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