The two companies filed for the extension in January 2007.
"In these times of economic uncertainty, this is great news for the state and its residents," Governor Palin said. "This extension will secure a future for the LNG operation and is another step toward ensuring energy supplies and energy security for Alaska."
In January, the state of Alaska and the owners of the LNG plant reached an agreement that will help ensure adequate supplies of gas for local utilities and encourage gas exploration.
The agreement requires the owners to develop additional natural gas reserves in Cook Inlet and allow third parties the opportunity to monetize their gas production through the LNG plant.
Marathon and ConocoPhillips have also agreed to sell Cook Inlet seismic and well data to third parties.
The Kenai LNG facility, located in Nikiski, is the only LNG export plant in North America.
The facility initiated operations in 1969 and today employs 58 people; the plant also supports 128 other jobs in the Kenai community.
In addition, the operations of the plant contribute approximately $50 million in royalties and taxes to the state and local economies.