Since 2013, REGEN Scenarios have explored key technology, policy, and market uncertainties that drive changes in the long-term energy mix and electric sector evolution. The REGEN model and REGEN scenarios have adapted to reflect the evolution of the energy sector in the last 10 years. Technology costs, the policy environment, and the REGEN model itself have all changed substantially over this period. This review analyzes key findings across scenarios to gives new insights into key uncertainties, highlights key modeling choices for a changing energy environment, and provides guidance for future REGEN Scenarios.
Over the last 10 years, the REGEN Scenario reference cases have consistently projected natural gas being the primary source of generation. Wind and solar capacity expands as well, with the rate of expansion depending on gas prices, renewable costs, and emission policies. There has been a shift in focus towards deeper decarbonization pathways in recent years, and the REGEN model and scenarios in later years reflect this shift. In deeper decarbonization scenarios, the generation portfolio depends on whether the policy is technology neutral or only credits a subset of technologies. Carbon capture and sequestration consistently plays an important role in technology neutral low carbon scenarios. Transmission expansion and greater utilization of the transmission network are also important for cost-effectively meeting decarbonization goals.