ROBBINSTON, Maine — The final proposal for a liquefied natural gas terminal in Down East Maine has quietly faded away, underscoring dramatic changes in energy markets in the past decade.

Federal regulators terminated the application by Downeast LNG because of inactivity, citing a lack of progress despite multiple requests for extra time to line up investors.

“There has been essentially no progress at all toward completion of an application in the past nine months and Downeast has presented nothing to persuade us that its situation is likely to change in the immediate future,” the Federal Energy Regulatory Commission said last month.

The proposal could be resubmitted later, but it would have to start over, from the beginning.

There was no immediate response from Downeast LNG.

Downeast LNG initially proposed an import facility a decade ago when projections for increased demand spurred proposals for LNG terminals in a half-dozen coastal communities in Maine to meet the nation’s demand for natural gas. Those included Harpswell and Sears Island.

Then came the North American energy boom thanks to new techniques for retrieving natural gas from shale. Downeast LNG adjusted to the rapid change by modifying its proposal to become an import-export terminal.

In the end, there was yet another major shift as the ample supply caused prices to plunge, reducing demand for U.S. exports, said Patrick Woodcock, director of the governor’s energy information office.

Before the so-called fracking boom, the U.S. had 11 LNG import facilities, six of which now feature export facilities approved by regulators and under construction, said Charlie Riedl of the Center for Liquefied Natural Gas. Another two export facilities are approved but not under construction.

In Maine, several LNG proposals were filed with federal regulators. One of them, a joint partnership with the Passamquoddy Indians, was rejected in 2008. Another one, Calais LNG, was rejected in 2012.

Save Passamaquoddy Bay opposed all of the proposals in the region, contending dramatic tides and rocky coasts made the bay a hazardous place for ships hauling LNG.

Save Passamaquoddy Bay spokesman Robert Godfrey was elated by the news from FERC.

“We did it! We defeated three developers with deep-pocket investors and with numerous lawyers and law firms, against all odds,” he said.