Approximately 25% of the fibre produced worldwide comes from cotton production. Although it is grown in around 80 nations, the United States, China and India continue to be the biggest producers, together making up more than half of the world's total. However, there are serious environmental issues associated with this large output. Cotton waste, comprising gin by-products and field wastes, amounts to millions of tons each year. Agricultural output is hampered by slow soil decomposition, also insect and disease problems are made worse by waste build-up. Cotton stalks and gin waste are perfect for producing renewable energy due to their lignocellulosic composition. Biofuels like ethanol, bio-oil, and fuel pellets are produced by processes including pyrolysis and fermentation, which can take the place of fossil fuels and lower carbon emissions. Cotton waste serves as a base material for producing high-value products, such as low-cost animal feed, substrates for mushroom cultivation, activated carbon for wastewater treatment, and bio-based building materials like particleboards. Research also shows that it can be used to synthesize enzymes and seal lagoons. Since using cotton waste not only reduces environmental issues but also promotes the circular economy by reducing dependency on non-renewable resources and increasing resource efficiency, this review highlights the conversion of numerous by-products from cotton waste. In order to boost product yields and economic viability, future research should concentrate on refining pre-treatment techniques, optimizing biomass conversion technologies, and investigating biotechnological developments.

Cotton waste, Lignocellulosic biomass, Renewable energy, Biofuels, Agricultural residue management

Cotton waste, a significant by-product of cotton farming and processing, poses environmental challenges such as soil degradation, greenhouse gas emissions, and pest proliferation due to improper disposal methods like landfilling and incineration. However, it also presents economic opportunities. Cotton stalks and gin waste, with their lignocellulosic composition, can be used to produce renewable biofuels such as ethanol, bio-oil, and fuel pellets, reducing dependence on fossil fuels and lowering carbon emissions. Furthermore, cotton waste can be transformed into valuable products like activated carbon for wastewater treatment, animal feed, mushroom cultivation substrates, and bio-based construction materials, such as particleboards. These by-products also serve as a substrate for enzyme production, supporting industrial processes. The sustainable utilization of cotton waste addresses environmental concerns by reducing landfill use, mitigating soil erosion, and lowering greenhouse gas emissions. Future research should focus on improving biomass conversion technologies like pyrolysis, fermentation, and gasification, as well as developing cost-effective pre-treatment methods to enhance product yield and quality. Advancements in biotechnology, such as genetically engineered microorganisms, could optimize enzymatic hydrolysis and fermentation processes for bioethanol production. Integrating cotton waste into circular economy models would further boost its scalability and promote sustainable practices. Policymaking, focused on encouraging sustainable agricultural practices and incentivizing bioenergy projects, will be crucial in unlocking the full potential of cotton waste. By transforming these residues into renewable energy and high-value products, cotton waste can shift from being an environmental burden to a driver of economic growth and sustainability, aligning with global efforts to foster a greener, more resource-efficient future.

Gogari, Samar, Radha and Sharma, Niharika (2025). Cotton Waste a Source of Sustainable Energy- A Review. International Journal of Theoretical & Applied Sciences, 17(1): 01–08.