Environmental Engineering Reference
In-Depth Information
RoleofGasStorageinTransmissionandDistribution
Underground storage is an essential component of an efficient and reliable
interstate natural gas transmission and distribution network. The size and
profile of the transmission system often depend in part on the availability of
storage. Access to underground natural gas storage facilities, particularly those
located in consuming areas, permits a mainline transmission pipeline opera-
tor to design the portion of its system located upstream of storage facilities to
accommodate the level of total shipper firm (reserved) capacity commitments
and the pipeline's potential storage injection needs (baseload requirements).
The segment of the transmission system downstream of the storage area
(including LNG peaking facilities) is designed to accommodate the maxi-
mum peak period requirements of shippers, local distribution companies,
and consumers in the area. It is generally sized to reflect the total peak-day
withdrawal (deliverability) levels of all storage facilities linked to the system
and estimated potential peak period demand requirements.
Some underground storage facilities are located in production areas at the
beginning of the pipeline corridor and, in contrast to storage near consum-
ing markets, can store gas that may not be marketable at the time of produc-
tion. For instance, natural gas produced in association with oil production
is a function of oil market decisions that may not coincide with natural
gas demand or available pipeline capacity to transport the gas to end-use
markets. Another example is the storage of natural gas produced from low-
pressure wells that may be injected into storage during the off-peak season
and delivered at high pressure to the mainline in the peak season.
In August 1991, FERC's Office of Economic Policy (OEP) released a discus-
sion paper recommending that the commission improve natural gas market
efficiency by recognizing and encouraging development of natural gas mar-
ket centers (hubs), defined by FERC as places on the natural gas pipeline grid
where buyers and sellers can make or take delivery of natural gas. FERC's
definition requires that hubs must be near the intersections of several pipe-
lines and, for convenience and balancing, should also be near fairly large
production or storage areas. Order 636 promotes the use of hubs by requiring
equal access to free markets for all gas industry participants through unbun-
dling pipeline services and prohibiting pipeline tariffs from inhibiting the
use of hubs (Beckman et al., 1995).
Two-thirds of the lower 48 states are almost totally dependent on the inter-
state pipeline system for their supplies of natural gas (Figure 8.6). On the
interstate pipeline grid, the long-distance, wide-diameter (20 to 42 inch),
high capacity trunk lines carry most of the natural gas transported through-
out the nation. In 2007, more than 36 trillion cubic feet (Tcf) of natural gas
were transported by interstate pipeline companies on behalf of shippers. The
30 largest interstate pipeline systems transported about 81% (29.8 Tcf) of the
total. Natural gas is commonly routed through several interstate pipeline
