The ability to add capacity to an interstate pipeline is commonly described as either “capacity additions” or “market need.” The technical configuration of a proposed project will determine how it operates as part of the overall network. In connection with the Federal Energy Regulatory Commission’s (FERC) review of the South System Expansion 4 (SSE4) proposal by Southern Natural Gas Company, FERC has identified the facilities and system modifications that would comprise the SSE4 project.
The identification of facilities and system modifications, and their relationship to each other
The identification should provide a better understanding of how the proposed SSE4 project would be expected to function as part of the existing network.
The facilities and system modifications proposed in the SSE4 project would include 14 non-contiguous natural gas pipeline loops constructed parallel to the existing South Main Line of Southern Natural Gas Company. In total, the proposed loops would cover approximately 279 miles of pipeline extending from Mississippi, Alabama, and Georgia. All of the proposed looping segments would be located within or immediately adjacent to existing pipeline right-of-way.
In addition to the proposed looping segments, the SSE4 project would involve significant changes to existing above-ground facilities. FERC’s Technical Overview of the SSE4 Project identified major expansion projects at 13 existing compressor stations, the construction of five new meter or regulator stations, and modifications to 11 existing meter stations. These facilities would be used to collectively support increased volume through the system via the looping segments, but would not require the construction of a completely new main line.
Compression and flow management improvements
The addition of compression upgrades would represent one of the primary components of the SSE4 project. By increasing horsepower at existing compressor stations, the project would allow for increased throughput while maintaining operational flexibility throughout the larger Southern Natural Gas Company system.
The ability to add capacity to the system on an incremental basis and to target the addition of capacity to areas of constraint within the system would result in the ability to meet the demand for the delivery of natural gas to multiple end-use markets.
FERC documents indicate that the combination of looping and compression would result in approximately 1.3 million dekatherms per day of additional transportation capacity. On a technical basis, the proposed design represents a system optimization strategy that is designed to utilize existing infrastructure to its maximum potential while limiting land disturbance associated with the construction of a new pipeline.
The metering and system integration in focus
Another component of the SSE4 project would be the addition and modification of meter and regulator stations. Metering and regulating stations are critical to the accurate measurement of the volume of gas being transported through the system, to the control of gas pressure, and to facilitate connections between upstream pipelines and customers. Through the addition of metering and regulating stations in conjunction with the installation of looping segments and compression upgrades, the project would seek to ensure reliable delivery of increased capacity to multiple market points within the Southeast.
FERC’s Technical Overview highlights the importance of the addition and modification of metering and regulating stations to system integration. The integration of the expanded South Main Line with existing Southern Natural Gas Company and Elba Express assets would be enabled by the upgrade of metering infrastructure associated with the new looping segments and compression upgrades.
A predominantly brownfield design
One of the defining technical features of the SSE4 project is its primarily brownfield design. Virtually all of the proposed new facilities would be located along existing pipeline corridors or at existing compressor and meter station locations. A brownfield design minimizes construction complexity and reduces the potential environmental impact associated with the construction of a large-scale greenfield development, while providing a significant amount of additional capacity. On a regulatory basis, this type of approach would allow FERC to evaluate individual facility upgrades.
