The United States Energy System Has Become More Volatile and Harder to Predict

Long-term projections of energy consumption, supply, and prices heavily influence decisions regarding long-lived energy infrastructure. Predicting the evolution of these quantities over multiple years to decades is a notoriously difficult task. This work provides the first effort in the literature to estimate volatility and unpredictability over multi-decade time frames for many quantities in the US energy system using historical projections. We determine the distribution over time of the most extreme projection errors (unpredictability) from 1985-2014, and the largest year-over-year changes (volatility) in the quantities themselves from 1949-2014. Critically, we find that both volatility and unpredictability have increased in the past decade, relative to prior decades. We encourage energy decision-makers to consider these findings, emphasizing robustness as they invest in and regulate long-lived energy infrastructure in a deeply uncertain world.