FERC on Tuesday approved the request of Distrigas of Massachusetts LLC to install facilities at its liquefied natural gas (LNG) import terminal to meet tighter natural gas quality standards of pipelines serving the Northeast.
Specifically, Distrigas intends to install a heating value and Wobbe Index reduction (HVWIR) system at its LNG terminal in Everett, MA, replacing its existing air injection equipment with a liquid nitrogen-based system that would be used to conform import LNG received at the terminal to new natural gas quality and interchangeability specifications.
The project will consist of two liquid nitrogen storage tanks, each with a nominal capacity of 120,000 gallons; ambient pressure coils; and insulated stainless steel piping and associated facilities.
Distrigas, which is located near Boston Harbor, purchases LNG from foreign sources and resells the LNG in liquid and vapor form to customers in the Northeast. LNG is delivered in liquid form by highway tanker trailers to storage tanks of local distribution companies and to end-users, and regasified LNG is delivered to Boston Gas Co.; the interstate pipeline systems of Algonquin Gas Transmission LLC and Tennessee Gas Pipeline; and Constellation Mystic Power LLC’s generation plant in Everett.
Until now, Distrigas said its existing air injection system had been sufficient to adjust the heating value and Wobbe Index of the revaporized LNG to meet the gas quality and interchangeability requirements of the interstate pipelines that connect to Distrigas. However, both pipelines have implemented or are in the process of implementing tougher standards.
Algonquin has implemented revised tariff specifications for gas transported on its system, introducing for the first time limits on maximum heating value, Wobbe Index and certain constituents of natural gas, including oxygen. Tennessee also has proposed revised gas specifications that raise the maximum heating value and add a Wobbe Index maximum, the Federal Energy Regulatory Commission order said [CP11-485].
“[Distrigas] asserts that because of these changes, certain LNG supplies will require additional conditioning to lower the heating value and Wobbe Index prior to delivery to the interstate pipelines,” it said.
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