​The power sector’s shift from large, inflexible generation to smaller, more dispersed variable renewable resources has triggered a debate among some U.S. policymakers about reliability and the continued need for baseload power plants, such as coal and nuclear. Yet numerous studies sponsored by utilities, system operators, the national labs, and others show that a large share of variable renewable energy production can be integrated while keeping the lights on, without any valuable role for traditional baseload. American policymakers who are still skeptical can look across the Atlantic for a concrete example of a successful transition away from traditional baseload. Germany, which traditionally relied on a significant share of inflexible thermal generation such as coal and nuclear to supply the grid, now meets nearly a fifth of its energy demand with variable renewables. This Energiewende, or energy transition, has been accomplished without reliability problems on either the distribution or bulk electric system—if anything, government data show that the reliability of the German system has increased.

In this article, written for Public Utilities Fortnightly, the authors review Germany’s reliability data in detail and discuss how reliability and least cost are best served by increasing the share of flexible resources on the system. Germany’s energy transformation envisions a grid where conventional thermal generation would follow “net load,” meeting short-term energy demand in some hours and the demand for flexible reserves in other hours, and variable renewables such as wind and solar would provide the bulk of energy over a regional grid. For U.S. regulators, the Energiewende provides important evidence that this type of system can be reliable and is attainable.​