Expert elicitation is a structured approach for obtaining judgments from experts about items of interest to decision makers. This method has been increasingly applied in the energy domain to collect information on the future cost, technical performance, and associated uncertainty of specific energy technologies. This article has two main objectives: (1) to introduce the basics of expert elicitations, including their design and implementation, highlighting their advantages and disadvantages and their potential to inform policymaking and energy system decisions; and (2) to discuss and compare the results of a subset of the most recent expert elicitations on energy technologies, with a focus on future cost trajectories and implied cost reduction rates. We argue that the data on future energy costs provided by expert elicitations allows for more transparent and robust analyses that incorporate technical uncertainty, which can then be used to support the design and assessment of energy and climate change mitigation policies.V. Bosetti would like to acknowledge funding from the ERC (grant agreement 336703 – RISICO). L.D. Anadón, L. Aleluia Reis and E. Verdolini would like to acknowledge funding from the European Union’s Horizon 2020 research and innovation programme (grant agreement 730403 – INNOPATHS)
