In 2001, on request of the Danish Parliament, the Danish
Energy Agency formed an expert group to investigate the
problem of excess electricity production arising from the
high per cent of wind power and CHP in the Danish energy
system [30]. As part of the work, Aalborg University made
a series of long-term year 2020 energy system analyses of
investments in more flexible energy systems in Denmark
[31]. These analyses were carried out by use of the
EnergyPLAN energy system analysis computer model
[32–34]. As a reference for the analysis, the expert group
defined a Danish future year 2020 energy system in
accordance with Danish long-term energy policies and
strategies.