Although Australia has yet to exploit any of its onshore underground salt deposits through the development of underground storage facilities that enable either the temporary or permanent storage of either gases, liquids, or solid wastes, the technical and economic viability of such facilities has been proven in many parts of the world, especially North America and Europe. Caverns dissolved in salt have been used for decades in various parts of the world to store hydrocarbons (oil, natural gas, ethane, propane…) and non-aqueous fluid products (e.g. ethylene glycol). The use of solution mined salt caverns for the storage of both liquids and gases is believed to have been first conceived in Canada in the early 1940’s and the storage of liquid hydrocarbons in salt caverns first occurred in Keystone, Texas, USA in 1950 and spread rapidly in the early 1950’s in North America and several European countries. While the first recorded underground gas-storage site opened in 1915 in Welland County, Ontario, Canada followed by a facility at Buffalo, New York, USA in 1916, the use of salt caverns for the storage of natural gas did not occur in North America until the 1961 facility located in Marysville, Michigan, USA followed by a facility in Saskatchewan, Canada in 1963. These facilities involved the brining of salt caverns in bedded salt deposits. The first leached storage cavern in dome salt occurred in 1970 at Eminence, Mississippi, USA for the purposes of natural gas storage. The creation of special purpose salt caverns for the storage/cycling of natural gas commenced in France and Germany in 1970 and 1971 respectively.
Thousands of salt caverns have been created throughout North America in both bedded and domal salt structures for various storage purposes. The storage capacity of such caverns range in size from 1,000 to 50,000,000 barrels per cavern for liquid storage and from 1 Bcf to 10 Bcf per cavern for natural gas storage. Salt caverns utilized for the cycling of natural gas tend to be much smaller than salt caverns used to cycle liquids because of the range of operating pressures inherent with natural gas storage operations.
The USA Strategic Petroleum Reserve (SPR) agency uses salt caverns leached in domal salt located in the states of Texas and Louisiana to store a strategic supply of crude oil stocks. As of 1997, the SPR had 650 million bbls of oil stored in 62 leached salt dome caverns. This supply of stored oil by an OECD country that is very reliant on oil imports is considered to be prudent. Australia would be well advised to adopt a similar risk management strategy.
The use of salt cavern storage has recently been expanded considerably to include the permanent storage or disposal of numerous wastes and the storage of various industrial gases, LNG and other commodities such as grain. Permanent waste disposal via salt caverns include the by-products of industrial plants, the petroleum and mining industries, greenhouse gases such as carbon dioxide, and nuclear waste. The Petroleum industries of Texas and Alberta extensively use salt caverns to dispose of non-hazardous by-products from petroleum drilling and production operations. Some countries are using underground salt mines for storing radioactive materials and the USA has successfully conducted a test storing nuclear waste in salt caverns.
The depth, stability, size and excellent containment properties of underground salt caverns make this form of storage increasingly attractive for a number of temporary and permanent storage applications worldwide