  The current governance process to plan the German energy system omits two
options to substitute grid expansion: First, placing renewables closer to
demand instead of where site conditions are best. Second, utilizing storage
instead of additional transmission infrastructure to prevent grid congestion.
In the paper, we apply a comprehensive capacity expansion model based on the
AnyMOD modelling framework to compare the status quo to alternative planning
approaches for a fully renewable energy system. To represent spatiality and
fluctuations of renewables, the German electricity sector is modelled with
great spatio-temporal detail of 32 NUTS2 regions and hourly time-steps. In
addition to the German electricity sector, analysis also accounts for exchange
of energy with the rest of Europe and demand for electricity and
electricity-based fuels, like hydrogen or synthetic gases, from the industry,
transport, and heat sector.
  The results reveal that a first-best solution can be well approximated if the
current planning approach also considered storage for congestion management.
Placing renewables different has no significant effect in our case, because the
available potential must be exploited almost entirely leaving little room for
optimization. Furthermore, a sensitivity on the first-best scenario prohibiting
additional transmission lines entirely suggests that grid expansion can be
substituted at tolerable costs.
