  Our research is centred around the question how to best integrate the
variable renewable energy sources (VRES), wind power and solar photovoltaics,
into the European electricity grid. The future electricity supply will be based
to a large extend on these fluctuating resources. We have conducted a study,
extrapolating national historical and targeted wind and solar power
penetrations in Europe up to 100% VRES (R.A. Rodriguez et al, Renewable Energy
63, p. 467, Mar 2014 and S. Becker et al, Energy 64, p. 404, Jan 2014). A high
share of VRES means large fluctuations in the generation, causing
overproduction and deficits. One way to reduce such mismatches is power
transmission spatially smoothing out the fluctuations. This has the potential
to reduce the remaining shortages by sharing the surplus production of others.
We find that shortages can at maximum be reduced by 40% in the hypothetical
case of unlimited transmission capacities across all of Europe. A more
realistic extension of the transmission grid, roughly quadrupling today's
installation, turns out to be sufficient to harvest 90% of this potential
benefit. Finally, the import and export of single countries is investigated. We
conclude that a country's load size as well as its position in the network are
the determining factors for its import/export opportunities.
