Under the IEA Net Zero Emissions scenario, renewables are projected to provide 90% of global electricity generation by 2050, a massive shift from today’s fossil fuel-dominated grid. Source: IEA Net Zero Roadmap 2023

Wind and solar are intermittent by nature, producing power only when environmental conditions allow. This misalignment between supply and demand creates new reliability concerns, especially during “Dunkelflautes,” multi-day periods of low solar and wind output. These events have become increasingly common across Europe, where renewables represent a growing share of electricity generation. These events reveal systemic stressors that must be accounted for in energy policy as wind and solar scale up.

Meeting long-term reliability needs will require solutions that complement variable renewable energy. California’s “Long Duration Energy Storage” program is one example of efforts to address the need for grid-scale storage capable of balancing multi-day fluctuations. Other regions, including Australia, Germany, and the Nordic countries, are experimenting with virtual power plants (VPPs): cloud-based control systems that coordinate distributed energy resources like rooftop solar, batteries, and smart appliances into flexible, dispatchable networks. These innovations provide short-term flexibility but cannot yet replace the firm capacity provided by low-carbon baseload sources. Today, technologies like nuclear, hydropower, and geothermal continue to offer stable generation regardless of weather or time of day. In Ontario, for example, nuclear accounts for over 50% of the electricity supply.

A high-renewables future is within reach, but without robust reliability strategies, the clean energy transition risks trading one form of energy insecurity for another.