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

Figure 4.4: Layout of Compressed Air Energy Storage (CAES) unit (Daneshi, 2010)
For storing compressed air, free space in geological underground like salt caverns,
aquifer structures or former groves can be used (see chapter 4.7 Energy storage of
pressurized gas). Such plants are able to reach their full power within about ten
minutes. Another advantage is that CAES plants normally only show very small
losses due to leakage. Small CAES plants could store the air in smaller storage tanks
or pipelines under higher pressure (100 – 140 bar) having the advantage of building
CAES plants independent from geologic conditions. Such plants contribute to
approximately 10 MW and can provide electricity for about three to five hours.
(Neupert, 2009)
To produce compressed air, many different compressors, which are operated with
different energy carriers, can be used. Many different technologies with diverse
volume and pressure exist. (Rummich, 2009)
If exhaust gases are used for preheating air, CAES plants can reach efficiencies up to
55 %. Other sources quote that efficiency of such plants range from 73% to 79%.
(Neupert, 2009; Alamri, 2009)
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