Technological features of a commercial fusion power plant, and the gap from DEMO

•In order to assess the commercial prospects of nuclear fusion as an energy source, consideration must be given to both its technological capabilities and to the market environment in which it finds itself.•In order to structure the thinking about this, EUROfusion takes three potential future power plant options in order to define what features they must have, and therefore assess the gaps between a current DEMOnstration power plant concept and a commercialisable option.•Approaching the issue this way highlights the role that such a DEMOnstration power plant must play beyond simply demonstrating the generation of electricity, but also in defining a regulatory environment, qualifying and lifing technology, and identifying the aspects of plant operation that may be accelerated between construction and full operation by optimising the commissioning process.