As with PHS, CAES costs are very site specific. The costs of mining a suitable underground cavern or creating an above-ground equivalent are at present prohibitive, whereas conversely alternatively a naturally occurring cavern can offer a very attractive price in $/kWh. It should be noted that the inlet pressure (45-76 bar) for the CAES high pressure turbine is much higher than the equivalent for a typical gas turbine (about 11 bar) so a typical gas turbine can only be used as the low pressure expander. The high pressure turbine at Huntorf is based on a small-intermediate steam turbine design. It is also worth noting that the Huntorf costs were considerably less than the equivalent cost in gas turbines in Germany at the same price date [5].