Anna University in Tamil Nadu is revisiting pioneering ethanol-fuel research conducted between 1975 and 1985, as India advances its ethanol-blended petrol programme and expands its focus on alternative transport fuels. The renewed research aims to examine ethanol performance at different engine compression ratios and explore flexible-fuel vehicle technology, bringing fresh attention to experiments that demonstrated the potential and limitations of ethanol decades before the current national blending drive.
The original project began after petrol prices rose from ₹4 to ₹6 per litre in 1973. Researchers at the College of Engineering, Guindy, led by Professor T. R. Jagadeesan, modified petrol engines to operate on 100% ethanol by changing components including the carburettor, ignition, cooling and heating systems. Road trials demonstrated that the engines could run on ethanol, but also highlighted its lower energy content and impact on fuel economy. 
In a 1979 test, a car delivered 7.2 km per litre on ethanol compared with 11.46 km per litre on petrol. Researchers subsequently improved engine performance by increasing a Fiat engine’s compression ratio from 7:1 to 11:1. Its reported thermal efficiency rose from 26% to 32%, demonstrating how engine design can influence ethanol utilisation. The team also tested ethanol blends in diesel motor pumps and a bus engine.
Despite successful demonstrations, large-scale adoption did not follow, partly because policymakers were concerned that using sugarcane for ethanol could compete with food production. Today, India’s ethanol programme has expanded significantly, with ethanol blending reportedly rising from below 1.5% in 2013–14 to 20% in 2025–26, five years ahead of schedule.
The renewed research comes amid continuing debate over E20 petrol, including concerns about mileage, engine compatibility, component durability, water consumption and food security. Ethanol offers potential benefits through reduced dependence on imported crude oil and greater use of domestically produced renewable fuels. However, outcomes can vary according to vehicle design, engine calibration and the feedstock used to produce ethanol.
Anna University registrar-in-charge V. Kumaresan said the university would participate in a research initiative involving IIT Madras and universities in China and Brazil. The Tamil Nadu government has allocated a research grant of ₹5 lakh.
The revived project could help generate evidence for flexible-fuel vehicles and future ethanol policies. Its significance will depend on the testing results and whether the findings can be applied across India’s diverse vehicle fleet while balancing energy security, consumer costs, agricultural demand and water resources.
