Gas consumption is not regular throughout the year. In France, for example, seasonal variations go from 1 in summer to 8 in winter. Storage of gas is therefore essential to enable matching of supply and demand. The most obvious method is that of storage in liquid form in giant tanks. But there is something better! The gas can be stored in natural underground reservoirs, as if one created an artificial gas deposit. Storage capacities are enormous, measured in billions of m³. And there is no need to refrigerate the gas to liquefy it.
Suitable geological sites must possess good reservoir and cap rock conditions and be located at a sufficiently
shallow depth (around 500m), so that injection of the gas is not too expensive in energy terms. Such ideal sites are not numerous. In France today there are 10 or so in operation. The most important is that of Chemery, in the Loir-et-Cher (capacity 7 billion m³).
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