The relevance of energy storages for an autarky of electricity supply ...

Regarding the electricity demand during the course of the year, Figure 3.3 shows that
consumption is higher in winter than in summer. This can be explained due to lower
temperatures and less sunny hours, resulting in a higher demand for electric
lightening throughout the day.
GWh
7.000
6.000
5.000
4.000
3.000
2.000
1.000
0
January Febuary March April Mai June July August September October November December
Nacional electricity consumption 2010
Figure 3.3: Annual electricity demand in Austria, 2010 (e-control, 2010)
These variations during time and in magnitude are almost always present and
constitute a serious challenge for electric utility firms that supply and manage the
transmission and distribution electric power grid. To hold the load level typically
different technologies exist. Operating reserves are available to the system operator
within a modest amount of time. Two different types exist: The spinning reserve can
be made available by relatively simple modifications, e.g. with the operation of
major turbines. Supplemental or non-spinning reserve name capacity, which is
currently not connected to the system but can be brought online after a short delay
(around 10 minutes). It includes fast-start generators or importing power from other
interconnected power systems. (Huggins, 2010)
13