A sign for the entrance of the Cheniere Texas LNG facility is seen in Portland, Texas. REUTERS/Callaghan O'Hare

(Reuters) - A construction permit extension for the planned expansion of Cheniere Energy Inc’s liquefied natural gas export facility in Texas was unwarranted, environmental groups told a Washington, D.C., federal court Wednesday, saying the expansion threatens to add to existing pollution burdens in the area and undermine efforts to address climate change.

The Sierra Club and Public Citizen petitioned the D.C. Circuit to toss the Federal Energy Regulatory Commission’s decision to extend the construction window for Cheniere's Corpus Christie export facility, claiming the expansion would mean an increase in greenhouse gas emissions from the plant equal to that of 17 coal-burning power plants. The groups have argued Cheniere has only conducted minor site preparation and that a new look at whether the expansion is necessary is appropriate.

“Cheniere’s polluting gas export facility is already a menace to surrounding communities, and this threat would be made even worse by its massive proposed expansion,” said Sierra Club representative Rebekah Hinojosa in a statement.

Cheniere spokesperson Phil West said in an email the expansion construction is "well underway" and expects to begin delivering LNG by the end of 2025. West said long-term contracts for LNG have been signed as customers "recognize LNG is a critical solution that supports energy security and the ongoing energy transition."

Cheniere last December requested an extension to its 2024 deadline to build its $8 billion Stage 3 expansion, telling FERC that it needed the extra time to complete the project following pandemic delays. FERC approved the extension amid a surge in demand from European markets due to the ongoing Russian invasion of Ukraine.

Once finished, the expansion would add up to seven liquefaction units and one LNG storage tank. The plant is currently home to three fully operational liquefaction units and three storage tanks, according to Cheniere. The site can currently produce roughly 15 million tons per year of LNG and the expansion would bring it to around 25 million tons per year, according to Cheniere.

The case is Sierra Club v. Federal Energy Regulatory Commission, U.S. Court of Appeals for the District of Columbia Circuit, No. not available.

For the plaintiffs: Nathan Matthews and Tom Gosselin of the Sierra Club

For FERC: Not immediately available

(NOTE: A Cheniere spokesperson's comment has been updated.)

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