No industry is as essential to the human condition as energy. It fuels our cars, lights our homes, and powers our businesses. The enterprise of creating and maintaining a durable energy system—the collective means by which society generates and distributes vital energy resources—has been around for generations. But longevity is not the same as constancy, and energy analysts have taken on the dual task of defining the status quo of the energy system as well as projecting its potential evolution. By proclaiming the dawn (or twilight) of various paradigms, periods, and ages, countless writers have attempted to make sense of this colossal and intensely global industry. Although no attempt to reduce the history of the energy industry into distinct sequential strata will ever capture its true complexity, these efforts are a useful means of assembling a coherent narrative to inform various public and private sector decision-making processes. One of the more important lessons instilled by even a cursory reading of this literature is that the energy system tends to move slowly, but changes to it can be swift and irrevocable, meaning that it is all the more valuable to reflect on and analyze the system.

The goals of this paper are threefold. First, it seeks to explain the various drivers of and constraints to changes in the energy system, whether technological, market-based, or political. Second, it provides a broad summary of our current understanding of the energy system, not through a fuel-by-fuel breakdown of supply and demand but by a survey of the major issues that most energy analysts consider crucial. Finally, it aims to combine the insights found in the outlooks of the industry’s major forecasters with a more speculative look at the less tangible forces that could shape the future of energy.