Apart from 48900 MT of ethanol annually, the plant will produce 19000 MT of furfural, 11000 MT of acetic acid, and 31000 MT of food grade liquid CO₂ from bamboo.
India is set to achieve a significant milestone in sustainable energy with the inauguration of the country's first bamboo-based ethanol plant by Prime Minister Narendra Modi on 14 September. Located at Numaligarh in Golaghat district, Assam, this state-of-the-art facility has been established by Numaligarh Refinery Limited (NRL), a subsidiary of the Indian Oil Corporation Limited (IOCL), with 26% of the shares held by the state govt.
The plant has been built with an investment of around Rs 5,000 crore aimed at promoting green energy, enhancing farmer incomes through bamboo cultivation, and reducing dependence on fossil fuels. The plant will be operated by Assam Bio Ethanol Private Limited (ABEPL), a joint venture between Numaligarh Refinery Limited and two Finnish companies, Fortum BV and Chempolis Oy.
The facility is designed to process lignocellulosic biomass, primarily bamboo, into ethanol and other value-added products like bio-chemicals, contributing to the economy. The plant will process around 500,000 tonnes of bamboo annually, and will produce 48,900 tonnes of ethanol, significantly contributing to 20% ethanol blending in petrol.
This is not just an ethanol producing plant, but a bio-refinery which will produce a range of products and byproducts from bamboo. Apart from bio-ethanol to be blended with fossil fuel, the bio-refinery will also produce furfural, a product used in making resins, acetic acid, and valuable by-products such as enzymes, formic acid and food grade carbon dioxide. The residue remaining after extraction of useful products will be used to generate power. The plant will produce 25 megawatts of electricity, of which 20 MW will be used internally, and the rest 5 MW will be supplied to the refinery.
Apart from 48900 MT of ethanol, the plant will produce 19000 MT of furfural, 11000 MT of acetic acid, and 31000 MT of food grade liquid CO₂ from bamboo.
The plant is also working with IIT Guwahati on a pyrolysis project to produce biochar from bamboo waste.
The refinery will source bamboo directly from around 3,000 farmers across Assam. The north eastern states have abundant supply of bamboo, a fast-growing grass plant. India's northeastern region is home to over 66% of the country's bamboo forests. After the closure of paper mills in the region, there is no large-scale use of bamboo, and therefore there will be no shortage of raw material for the bio refinery.
The biorefinery has already demonstrated its technical prowess by successfully producing 99.7% pure bamboo ethanol. This achievement underscores the plant's readiness for commercial operations and its potential to utilize Assam's abundant bamboo resources.
This initiative not only boosts local economies by creating jobs and supporting bamboo farmers but also aligns with India's commitments to reduce carbon emissions and achieve net-zero goals.
Ethanol or ethyl alcohol( C₂H₅OH) is a clear colourless liquid, biodegradable, low in toxins, and causes little environmental pollution if spilled. It is a high-octane energy source and has replaced lead as an octane enhancer in petrol.
The ethanol to be produced in the Numaligarh plant will be 2G ethanol. Notably, commercially produced ethanol is classified into generations, 1G, 2G, and 3G, based on the source of raw materials and the production processes involved. These categories reflect advancements in technology to address sustainability challenges, such as food security and resource efficiency.
1G ethanol is produced from edible crops rich in sugars or starches, such as sugarcane, corn, sugar beet, or grains like wheat and rice. The process is relatively straightforward, the feedstock is crushed or milled to extract sugars, which are then fermented using yeast to produce ethanol. This method has been in commercial use for decades and forms the backbone of India's current ethanol blending program, primarily sourced from sugarcane molasses.
However, 1G ethanol faces criticism due to the "food vs. fuel" dilemma. Diverting food crops for biofuel production can drive up food prices, strain agricultural land, and compete with human and animal feed needs. Additionally, it relies on fertile arable land and water-intensive crops, limiting scalability in densely populated countries like India.
2G ethanol addresses the limitations of 1G ethanol by using non-edible lignocellulosic biomass as feedstock. This includes agricultural residues like rice straw, sugarcane bagasse, forestry waste, energy crops like switchgrass, and dedicated plants such as bamboo or miscanthus. Unlike 1G ethanol, 2G ethanol feedstocks do not compete with food production, as they are derived from non-food sources.
The production process for 2G ethanol is more complex and energy-intensive. It involves pretreatment like steam explosion or acid hydrolysis to break down the tough lignocellulosic structure, which comprises cellulose, hemicellulose, and lignin, into fermentable sugars. These sugars are then hydrolysed, fermented, and distilled into ethanol. This requires advanced enzymatic or chemical technologies, making 2G costlier initially but more sustainable in the long term.
The Numaligarh plant is India's second 2G ethanol plant, and the first to use bamboo. A plant set up by Indian Oil in Haryana's Panipat to make ethanol from rice straw is the first such 2G ethanol plant in the country. That plant started operations in August 2022. Using rice straw to make ethanol can help in mitigating the stubble burning problem in India.
Bamboo is specifically useful to produce 2G ethanol because bamboo is a fast-growing, lignocellulosic grass that does not require fertile soil or excessive water, thriving in wastelands. It yields high biomass, up to 40 tons per hectare annually, and contains 40-50% cellulose, ideal for ethanol production.
In the Numaligarh plant, bamboo chips are pretreated and converted into ethanol, producing not just fuel but also byproducts like furfural and acetic acid, enhancing economic viability without impacting food security.
3G ethanol represents the next development in ethanol production, primarily sourced from microalgae or cyanobacteria cultivated in photobioreactors or open ponds. These microorganisms offer superior yields, up to 100 times more than 1G crops per unit area, and can grow in non-arable land, seawater, or wastewater, minimising environmental footprint. The process involves harvesting algae, extracting lipids or carbohydrates, and fermenting them into ethanol.
While 3G ethanol promises higher efficiency and lower land use, it remains largely experimental due to high costs, scalability challenges, and energy demands for cultivation and harvesting. Commercialization is expected in the coming years, but it is not yet widespread like 1G or emerging 2G technologies.
4G ethanol is an emerging concept in biofuel research, that combines advanced biotechnology, synthetic biology, and carbon capture to make fuel in a more sustainable way. It typically involves genetically engineered microorganisms or photosynthetic organisms that can directly convert carbon dioxide, sunlight, or waste gases into ethanol, rather than relying on crop-based feedstocks.
The idea is to create a carbon-neutral or even carbon-negative fuel, reducing greenhouse gas emissions while avoiding land-use conflicts. Though still largely at the research and pilot stage, 4G ethanol represents a future direction where renewable energy, industrial waste recycling, and cutting-edge biotechnology converge to produce cleaner liquid fuels.