The goal of maintaining current levels of energy supply and demand whilst reducing their carbon intensity will require greater use of renewables. As a result, new forms of flexibility will be needed. While the emerging “flexibility industry” promises solutions based on current configurations, this collection shows that the problem of managing fluctuations in the relation between supply demand is not new. The papers included in this special issue work with different approaches and scales of analysis, but all show that lessons for balancing energy supply and demand today can be drawn from the past. Just as important, they show that the legacies of past practices and infrastructures live on and have effect in contemporary energy systems.