The global electricity sector is moving away from fossil fuels at a pace that was hard to imagine a decade ago, and renewable energy technologies sit at the centre of that shift. This review examines the main renewable options for sustainable power generation, namely solar photovoltaics, wind, hydropower, bioenergy and geothermal energy, together with the storage and grid measures that allow them to supply dependable electricity. Drawing on peer-reviewed review articles and official capacity statistics published between 2022 and 2026, the paper summarises technology status, evidence on deployment effectiveness and the barriers that slow implementation, with particular attention to India. The evidence shows that solar and wind now account for almost all net renewable additions worldwide and that India has passed 300 GW of non-fossil capacity. However, installed capacity alone does not guarantee clean generation. Grid congestion, curtailment, storage costs and uneven regional access remain the main constraints. The review concludes that sustainable power generation depends less on any single technology than on coordinated investment in generation, storage, transmission and policy. Implications for Indian planners and directions for future research are discussed.