What would India need for moving to a 100% renewable energy scenario by 2050?

The Fifth Assessment Reports released by the IPCC indicates that increase in global temperatures is proportional to the build-up of long-lasting greenhouse gases in the atmosphere, especially carbon dioxide. Various models have estimated 680-1200 billion tonnes of CO2 as being the maximum volume of CO2 that could be emitted till 2100 into the atmosphere to still stay within the 2 °C limit. However, few countries have made efforts to move towards any major deviations from their past emission trajectories. Various studies such as the Emissions Gap report brought out by the UNEP indicate that the emission gap (defined as difference between what existing pledges can achieve and what is required over different time frames) is not becoming any smaller but more and more difficult to achieve. Pursuing an energy trajectory alternate to the historical fossil fuel dominant trajectory is widely regarded as the preferred policy option to rapidly reduce the emission gap without compromising with the imperatives of reducing development deficit. Renewable technologies not only provide a low carbon enhancement of energy security, but also have other crucial benefits like improving access to energy services, increasing the standard of living and levels of employment of the local population, reducing pollution, improving health, ensuring sustainable development of the remote regions in a country and so on. Moreover, renewables are amenable to adoption at various scales - ranging from a few kilowatts to hundreds of megawatts, and can therefore be adopted in modular standardized designs across a variety of end-use applications and in a decentralized mode. Renewables can also provide greater resilience to volatility in market prices of energy than conventional energy fuels. In addition to promoting renewable energy, improving energy efficiency across various sectors offers an excellent opportunity for linking sustainable development with climate mitigation. Improvements in energy efficiency in fact can bring with it a wide range of positive social impacts such as reduced air pollution and the consequent health benefits. Various studies indicate that several thousand premature deaths related to air pollution could be avoided annually by 2030 through energy efficiency measures in the transport, buildings and industrial sectors.