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

4.6.2 Key figures
Rated power
Sizes of CAES plants are available from 20 to 350 MW. (Neupert, 2009; Alamri,
2009)
Energy density (kWh/l or kWh/kg or kWh/m3)
The energy density for CAES is about 2 –5 kWh/m 3 21, 22
.
Energy content of the system
• Pore-space storage (see chapter 4.7 Energy storage of pressurized gas):
The volume of pore-space storage ranges from hundred million cubic meters up
to some billion cubic meters. About half of the volume can be discharged. The
maximum pressure in pore-space amounts to 60 – 80 bar.
Average energy density of CAES: 3.5 kWh/m 3
(13) 50 mil. m3 * 3.5 kWh/m3 = 175 GWh
(14) 1 bil. m3 * 3.5 kWh/m3 = 3.5 TWh
• Cavern storage (see chapter 4.7 Energy storage of pressurized gas):
The volume of cavern storage can amount up to 800,000 m 3 . As the maximum
volume of this storage system is much smaller, the energy content of this system
is also much lower.
Self-discharge rate/losses
As with hydrogen the salty walls of caverns are leak-proof for gas; therefore, no
losses occur. (see chapter 4.7 Energy storage of pressurized gas)
Availability
CAES plants are able to reach their full power within about ten minutes. (Neupert,
2009)
21 http://bravenewclimate.com/2009/08/31/solar-thermal-questions/, 20.10.2011
22 http://www.nrel.gov/docs/fy10osti/47547.pdf, 20.10.2011
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