  As the world is transitioning towards highly renewable energy systems,
advanced tools are needed to analyze such complex networks. Energy system
design is, however, challenged by real-world objective functions consisting of
a blurry mix of technical and socioeconomic agendas, with limitations that
cannot always be clearly stated. As a result, it is highly likely that
solutions which are techno-economically suboptimal will be preferable. Here, we
present a method capable of determining the continuum containing all
techno-economically near-optimal solutions, moving the field of energy system
modeling from discrete solutions to a new era where continuous solution ranges
are available. The presented method is applied to study a range of technical
and socioeconomic metrics on a model of the European electricity system. The
near-optimal region is found to be relatively flat allowing for solutions that
are slightly more expensive than the optimum but better in terms of equality,
land use, and implementation time.
