Alternate Fuels in Thermal Power Plants : Pathways to Decarbonization and Energy Transition

Coal-based power plants remain the backbone of India’s electricity system—contributing around 43 % of installed capacity and nearly 70 % of total generation and therefore bear the primary responsibility for managing the challenges arising from growing renewable penetration. Enhancing the environmental performance of these plants is therefore essential to ensure a reliable and sustainable energy transition.

India being an agro based and coal rich country, can leverage agro-biomass and methanol produced from captured CO2 and green hydrogen as viable pathways to reduce the environmental impact of thermal power plants. Agro-biomass co-firing can be carried out in coal-based units with minimal system modifications and can lower coal consumption, reduce emissions from open-field burning of agricultural residues, and support rural supply chains.

NTPC, India's largest integrated power utility, has fired about 18.38 lakh metric tonnes (MT) of agro-biomass across its coal-based power plants till date, demonstrating large-scale and sustained biomass co-firing under Indian operating conditions. Further, NTPC has successfully demonstrated agro-biomass co-firing at scale, including demonstration of up to 30% co-firing using torrefied biomass under Indian operating conditions, establishing its technical feasibility and environmental benefits. As a carbon-neutral fuel, agro-biomass displaces a portion of coal, thereby cutting net CO2 emissions and advancing the circular carbon economy.

Methanol produced from carbon capture from flue gas and green hydrogen offers an additional low-carbon pathway suitable for both coal and gas-based power plants. With appropriate system modifications, methanol can substitute conventional fuels such as naphtha, HSD, RLNG, and

HFO/LDO, enabling carbon recycling and supporting deeper decarbonisation of the thermal fleet. NTPC has successfully completed pilot-level demonstration of carbon capture from flue gas and utilisation of the captured CO2 for methanol production using hydrogen, establishing technical feasibility of Carbon Capture and Utilisation (CCU) under Indian conditions. Based on these pilot demonstrations, CCU-based pathways are now being positioned for scale-up to a wider range of value-added products, including methanol, ethanol, urea, and sustainable aviation fuel (SAF).

To enable long-term decarbonisation of the power sector, space provision for future CCU systems is being kept in all new power plants, making them future-ready for CO₂ capture from flue gas and downstream utilisation. In parallel, NTPC is implementing a first-of-its-kind pilot in India to demonstrate methanol firing in an existing gas turbine, aimed at evaluating combustion behaviour, emission performance, material compatibility, and system-integration requirements under utility-scale operating conditions.

This paper presents a consolidated assessment of both fuels, covering operational experience, environmental benefits, circular-carbon-economy contributions, CO2, SO2 and particulate matter reduction estimates and associated eco-design considerations. Together, these insights provide a structured and practical pathway for India and other countries facing similar energytransition challenges, for possible low carbon fuel solutions in existing coal and gas-based power assets.