This study compares two scenarios for 100 per cent renewable energy in India by 2051: the Reference Energy Scenario (REF) is compared with the Renewable Energy Scenario (REN). The REF scenario considers only current trends and policies, and projects these into the future as determinants of energy demand and supply. This scenario includes all current forms of energy – renewable and non-renewable – while in the REN scenario, fossil fuels and nuclear-based technologies are phased out and replaced, wherever possible, with renewable options. The study suggests that a sustainable, renewable-energy-based economy could theoretically be achieved, where as much as 90 per cent of India’s total primary energy supply could technically be based on renewable sources.