The state of Tamil Nadu is rich in renewable energy (RE) sources, especially wind and solar. Currently, approximately one-third of the country’s installed RE capacity exists in Tamil Nadu alone. The Action Plan for Comprehensive Renewable Energy Development in Tamil Nadu, aims to tap this abundant source of energy and make Tamil Nadu an energy-sufficient and energy secure state. The action plan is the result of a comprehensive analysis of renewable energy choices and their relevance to the present and future energy plans and energy security of Tamil Nadu for the next two five-year plans (2012–22). On a broad level, the project findings are striking and indicate that while the existing coal-based power sector planning of the state is exposed to huge risks, the re-assessed renewable energy potential is in multiples of the official estimated potential. The study also sheds light on important aspects related to technical integration and commercial acceptance of renewables and develops a renewable energy action plan and implementation roadmap for the state.