Humanity has continually strived to efficiently store commodities of all types. The purpose of storage is to resolve supply and demand imbalances across time, particularly to accommodate (if not to survive) fluctuations in either supply or demand. All commodities can be stored to a greater or lesser extent. Among energy commodities, coal and oil are the easiest to store, requiring little more than fields and tanks. Electricity, on the other hand, is extremely challenging to store; the amount of storage capacity for power is typically a minute fraction of total generation capacity and insignificant in comparison with the typical hourly variations in demand. This is why electricity production and distribution infrastructure must be extremely reliable; reliability often achieved at the cost of significant redundancies in the physical system.

Natural gas lies somewhere between these two extremes – it can be stored in relatively large quantities, provided that geologic formations exist that can be modified to hold natural gas at required pressures. The development of such facilities is expensive but not prohibitively so. As a consequence, the ratio of working storage capacity to total demand can be substantial. For example, as we saw in Chapter 3, in 2012, the United States had roughly 4.2 tcf of storage capacity with annual consumption of approximately 24 tcf per year. This has historically proven to be adequate to resolve the mismatch between the seasonal variations in demand and the relatively slow changes in production shown in Figure 3.24.