Today, the Energy Information Administration (EIA) published its first semiannual report of liquid fuels storage capacity data. EIA has reported weekly and monthly inventory levels of crude oil and petroleum products for decades. What’s new is that the new storage capacity data can help analysts place petroleum inventory levels in context and better understand petroleum market activity and price movements, especially at key market centers such as Cushing, Oklahoma.

Before today’s release, EIA published only annual data on storage capacity located at refineries. With today’s release, storage capacity data now include the following improvements.

* Expanded Coverage – In addition to refineries, storage capacity includes capacity at petroleum products terminals, fuel ethanol plants, product pipelines (tank and underground storage), and crude oil tank farms.
* More Frequent Updates – Unlike prior refinery-only data collection, new storage capacity data will be semiannual with data collected as of March 31 and September 30 each year. This schedule allows for more frequent updates to track changes in overall storage capacity and also allows for tracking seasonal shifts in petroleum product usage of tanks and underground storage.
* Market Center Information – In addition to standard regional reporting of storage capacity by Petroleum Administration for Defense Districts (PADDs), the new data provide storage capacity at Cushing, Oklahoma.

Using the new storage capacity data, it will be possible to calculate approximate storage capacity utilization rates at refineries and petroleum products terminals. Unfortunately, meaningful storage capacity utilization rates for operators of crude oil tank farms and pipelines, or for operators of products pipelines, cannot be readily calculated at this time. This is due to the fact that existing data on inventory levels at these facilities is reported on a different basis than the new storage capacity data. To address this, EIA is considering updates of crude oil and products pipeline surveys to require semiannual reporting of inventory levels on the same basis as storage capacity. This will enable data users to calculate storage capacity utilization rates for crude oil tank farms and pipelines as well as products pipelines.

As is often the case with energy information, the collection of storage capacity requires careful attention to detail. EIA reports both working storage capacity and net available shell storage capacity. The diagram below uses schematics for both tank and underground storage to illustrate these concepts.

The difference between working and net available shell storage capacity is equal to tank bottoms and contingency space. Tank bottoms are unavailable barrels below the normal suction line of a storage tank. In floating roof tanks, there must be enough barrels in tank bottoms to keep the roof floating. Contingency space is available storage capacity that normally remains empty in storage tanks or filled with brine in the case of underground storage caverns. Contingency space allows flexibility to exceed working storage capacity without disrupting operations or creating safety or environmental hazards that result from excess filling.

EIA collects working storage capacity for operating tanks and caverns: those that held inventory on the report date as well as any that were empty but were available for immediate service. EIA also collects net available shell storage capacity for those same tanks and caverns. In addition, net available shell storage capacity also includes idle storage capacity. Idle storage capacity is not available for service but could be made available within 90 days of the report date following time for maintenance. Storage capacity that cannot be made available for use within 90 days is out of scope of our data collection and excluded from storage capacity totals

EIA collects additional storage capacity information from petroleum products terminals and crude oil tank farms to show capacity that is held for exclusive use by facility operators or that is leased to other companies. EIA does not subdivide individual tanks or caverns with regard to capacity held for exclusive use and capacity leased to others. If any portion of a tank or cavern is leased to another company, or if the capacity is typically made available for lease to others, then the entire capacity of the tank or cavern is reported as leased to others.

Source: U.S. Energy Information Administration