Hydro, wind, and solar power can play a pivotal role in the evolution of global energy to support both energy security and the transition to low-carbon emissions. The extent and rate of expansion of these resources will be driven by several interrelated factors, including demand growth due to socio-economic growth, energy transition to low-carbon with net-zero emission targets, and advancement of evolving supply technologies. We use the Global Change Analysis Model (GCAM) to explore the future global expansion of hydro, wind, and solar power and their anticipated rate of expansion in scenarios with varying demand growth, long-term energy transitions, and technological advancements. Our results indicate that wind and solar combinedly can contribute to a major share of future global electricity generation – rising from less than 10% in 2015 to an end-of-century share of 20-35% in scenarios without technological advancement. The declining cost of the variable renewables with technological advancement can raise their end-of-century share to 55-75% under different demand growth and net-zero emission goals. The generation share of hydropower, on the other hand, is likely to decline from 16% in 2015 to 5-10% in 2100 across all scenarios, partially because of declining cost-competitiveness with wind and solar, but also because its expansion is constrained by resource availability. Despite a declining share in total generation, 50-80% of the global exploitable hydropower resources (~16.6 PWh/y) could be exploited by 2100 in scenarios without technological advancement. However, with technological advancement, higher integration of wind and solar can help avoid 10-15% of the global hydro-exploitation. The regional scale annual rate of expansion of hydro, wind, and solar for different scenarios will be discussed.