The growth of the Indian petrochemical industry can be made sustainable only by mitigating the emissions from it. This study examines the decarbonisation potential of India’s petrochemical sector until 2050 through low- or zero-emission technologies. It also underlines measures for decarbonising this hard-to-abate sector, with the aim to provide inputs for devising suitable strategies and guide policy formulation. Considering the diversity and complexity of the petrochemical industry, the study is focussed on ethylene—the basic chemical building block for daily-use products like plastics and textiles—and adopts a modelling approach to estimate the emissions arising from domestic ethylene production. The model is based on the concept of system dynamics and is used to examine various plausible scenarios, such as energy efficiency improvements, circular economy strategies, carbon capture and storage (CCS), and decarbonisation through changes to the source of energy (electrification, green hydrogen). The total emissions arising from ethylene production are estimated on the basis of specific energy consumption (SEC) numbers and the share of various feedstocks (naphtha, natural gas, ethane, dual feed).