written by Barasha Das
- Brick-making businesses in Assam are exploring ‘green’ bricks which they find have economic and environmental benefits.
- Fly ash bricks is one such option, though Assam has limited fly ash availability.
- A study by the Assam Climate Change Management Society highlights the environmental damage caused by traditional brick kilns and advocates for green technologies.
Ritesh Karamchandani, a Guwahati-based third-generation red-brick manufacturer, owns brick-making units in Azara on the city’s outskirts. He closed his family-operated kiln in 2011 after 54 years of operation. “Since then, I have been manufacturing fly-ash bricks and blocks, a better alternative. Our kiln was reputed for producing top-quality bricks in Guwahati. To maintain this standard, we continuously conducted research and made necessary changes. This research led me to switch to green bricks once I realised they were a better option,” he says. Green bricks, including fly ash bricks, are produced through processes designed to be low carbon, low emission, and environmentally sustainable.
To learn the tricks of the trade, he attended annual trade fairs, visited operational plants, and talked to different machine manufacturers before setting up the new plants. “A major driving force (for the switch) was the economic factor. Unlike traditional brick kilns, the green brick industry is not very labour-intensive, and since it is not polluting, I don’t have to worry about hassle from the Pollution Control Board (PCB). Moreover, in Assam’s climatic conditions, brick kilns, which need fire, can hardly operate for four to five months a year because of frequent rain for the rest of the year. It always makes more sense to be eco-friendly as it does not need fire,” he added.
Another clay brick manufacturer, who wished to remain anonymous, highlighted the challenges of the traditional method. A second-generation manufacturer on the outskirts of Guwahati, he said the biggest challenge traditional brick makers in Assam face is changing rainfall patterns.
“Previously, our manufacturing units would remain closed for about five months during the monsoon season, following a relatively predictable schedule. Now, however, we experience sudden rainfall, even between October and December, disrupting our firing rounds. In the past, we could manage at least three rounds of firing, producing 600,000 bricks in each round. Now, we can hardly complete two or two and a half rounds,” he said.
However, the availability of fly ash for the green bricks, is limited, notes a study by the Assam Climate Change Management Society (ACCMS), released in February this year. Fly ash is captured after coal combustion, as a waste material from thermal power plants. But, the study notes, Assam has only one coal-based thermal power plant in Bongaigaon. “We procure it from the Bongaigaon thermal plant, as well as from Malda, Jamshedpur, and other places in West Bengal for the cement industry,” said Karamchandani.
There are currently about four to five units making bricks from fly ash, in Assam. Karamchandani, though, is hopeful for the future. “There is a growing market for alternative building materials in Assam,” he said. “Back in 2011, I operated a small plant producing approximately 80,000 (fly ash) bricks monthly. In 2022, I invested in a more automated facility, significantly boosting output to 150,000 bricks per month. My clientele spans various sectors, using fly ash bricks for constructing factories, warehouses, private buildings, and boundary walls. I have noticed a recent increase in customers from rural areas building houses with fly ash bricks.” Seeing the emerging market, he plans to add more eco-friendly construction materials.
Fly ash is a waste material from thermal power plants but its disposal is a major environmental concern. India’s coal-fired power plants generate approximately 196 million tonnes of fly ash annually. Currently, 9.01% of fly ash is used in bricks and tiles in India, compared to 19.60% in China for the same category. The government of India has been pushing for the effective use of fly ash to counter the issues with its disposal.
Unsustainable path of traditional bricks
Assam reportedly contributes around two million tonnes (MT) of carbon emissions from the burnt clay brick sector every year. There are about 1,242 operational traditional brick kilns in the state, producing roughly 37,260 lakh bricks annually, notes the ACCMS pre-feasability study on the implementation of green bricks which also discusses the need for promoting sustainable methods of producing green bricks.
Similar to the rest of India, the Assam’s brick sector is predominantly dependent on the conventional coal-fired Fixed Chimney Bull’s Trench Kiln (FCBTK) and clamps, consuming substantial amounts of coal and fertile topsoil. This set up, nationally, emits 66 to 84 MT of CO2 annually and the Ministry of Environment, Forest, and Climate Change has suggested phasing out these kilns.
The sector is also dependent on clay for the production of unfired bricks and strips approximately 9.68 million tonnes of fertile soil each year, primarily from agricultural land. Around 215 sq km of agricultural topsoil has been lost to brick-making between 2012 and 2022, according to the ACCMS study.
The study further says that Assam’s brick sector primarily relies on coal to fuel the kilns with no usage of alternative materials such as biomass, oil, or gas. Additionally, an average of 18-20 tonnes of wood is used in FCBTKs during the initial firing to evaporate moisture accumulated in the kiln during the rainy season.
In a well-managed and properly fired kiln under Indian conditions, the Specific Energy Consumption (SEC) typically ranges between 1.10 to 1.20 MJ/kg of fired brick. However, Assam has a high SEC of 1.59 MJ/kg. Owing to the heavy rainfall and an average humidity that persists almost throughout the year in the state, unfired bricks always retain a moisture content of 5-10% even after the initial drying process, which ideally has to be reduced to below 0.5% for optimum firing. This leads to approximately 30% extra consumption of fuel (coal), the ACCMS study highlights.
Approximately 670,680 tonnes of coal are consumed annually and procured from Assam, Meghalaya, and Nagaland. The study stated that the use of these “immature, bituminous, low-quality coal” with 5-11% sulphur content causes high CO2 and SO2 emissions, “contributing to anthropogenic climate change.”
As brick consumption continues to rise, brick-making activity is projected to cumulatively consume approximately 593 sq km of agricultural land by 2030 and 3,101 sq km by 2050. This trajectory is poised to impact food grain production in the state and exacerbate flood situations and waterlogging issues, stated the study.
Need for green bricks
Given the pressure on natural resources due to high brick kiln demand, the ACCMS study advocates adopting new raw materials like fly ash and transformative technologies in Assam and other states in northeast India. It also makes recommendations about kiln designs and emphasises Vertical Shaft Brick Kilns (VSBK) over Bull’s Trench Kilns (BTK). VSBKs are tall, vertical structures with multiple shafts, more efficient and eco-friendly than BTKs. VSBKs offer significant fuel savings (30-50%) and shorter firing periods (3-4 days vs. 15-20 days for BTKs). They require less land and help control deforestation, reducing emissions by approximately 90% compared to traditional kilns.
Besides VSBKs, the study suggests several other types of kilns for sustainable brick-making. Replacing FCBTKs with zig-zag kilns could reduce GHG emissions by 20%, VSBKs by 40%, and CSEBs by up to 90%, it says.
The Guwahati manufacturer who wishes to remain anonymous says that despite challenges in the FCBTK, local manufacturers aren’t aware of new technologies and eco-friendly brick-making processes. The primary setback is the lack of knowledge. “Although the government has ordered the discontinuation of FCBTK and the shift to VSBK, no guidance has been provided. Most kiln owners are at a loss. Additionally, deconstructing the existing chimneys and constructing new ones requires a significant investment of at least Rs. four to ten million. Some hand-holding and financial assistance from the government would have been more helpful,” he added.
Karamchandani stated, “We need to promote fly ash bricks. It is the soot that otherwise flies out from the chimney and is highly polluting. It contains silica, which produces very high-quality bricks when mixed with cement, sand, and gravel.”
Explaining the economics of fly ash-based brick making, he says that in clay brick manufacturing, the capital requirement is substantial due to the large amount of land needed and the high costs of constructing the kiln and chimney. Additionally, over 200 labourers are required, necessitating significant advance payments to labour contractors. Due to the scarcity of labour, expensive JCB machines are also needed. In contrast, the investment required for manufacturing fly ash bricks and blocks is much lower. However, the substantial investment in clay brick manufacturing also results in higher profits, he said.
Harish Borah, a cost-carbon expert in the building industry, observed, “The building industry is actively striving to transition into a ‘net-zero’ GHG emitting entity, with national-level codes like the Energy Conservation Building Code (ECBC) and ECBC-R enhancing building energy efficiency standards to lower its carbon footprint. However, equal thrust has to be levied to address emissions from the manufacturing of construction materials. Initiatives that encourage the use of low-carbon materials in building by-laws, a component currently absent in Assam’s regulations, are crucial. In the case of the brick sector, prioritising low-carbon alternatives will align it with India’s 2070 net-zero target and ensure bricks remain a sustainable building material for the future.”
This article is republished from Mongabay under a Creative Commons license. Read the original article here.