Maritimes & Northeast Pipeline LLC, which ships natural gas from Canada through Maine and on to Massachusetts, confirmed Tuesday that it wants to triple the capacity of its 850-mile pipe system.

The project would include construction of five compressor stations and some “looping,” or installation of additional pipeline, in its existing right of way in Maine, according to Marylee Hanley, a company official based in Waltham, Mass.

“We haven’t even begun surveying the land yet,” she said Tuesday. “We’re in the very beginning stages.”

It is too early in the process to identify specific sites, but Hanley said the additional compressor stations in Maine would be in Township 35 in northern Hancock County, Brewer, Searsmont, Westbrook and Eliot.

The existing pipeline enters Maine near Baileyville in Washington County and runs to the New Hampshire line in the southern part of the state.

The expansion also would include one compressor station in Methuen, Mass., as well as additional stations in Canada, said Hanley, who is manager of government and public affairs for Maritimes & Northeast.

The additional product to be transported through Maritimes’ pipeline would likely come from two Canadian liquefied natural gas terminals, proposed for Nova Scotia and New Brunswick. A similar project has been proposed in various parts of coastal Maine, but whether any LNG terminal will be built remains uncertain.

Hanley said she could not estimate how much additional pipe would be constructed or whether additional drilling would be needed beneath Maine rivers. The existing pipeline runs through shafts drilled through bedrock beneath the St. Croix, Penobscot, Kennebec and Androscoggin rivers.

It is also too early in the process to put a price tag on the overall project, she said.

The company already has begun to notify towns in Maine where it expects to be doing construction, and Hanley said details of the project should be completed by the end of the year. That’s when it plans to file an application with the Federal Energy Regulatory Commission.

Maritimes officials have set a target date of November 2008 for the new capacity to come on line.

Maritimes is owned by affiliates of Duke Energy, the majority owner, Emera Inc. and Exxon Mobil Corp.

Earlier this year, Maritimes announced an open season to gauge customer interest in additional transportation services for new supplies of natural gas expected to become available, including liquefied natural gas.

“That open season was extremely successful, and a number of shippers requested additional capacity in the pipeline,” Hanley said.

The project would increase the capacity of the pipeline from its current 440 million cubic feet per day to 1.5 billion cubic feet per day. The pipeline came on line in 2000.

The company is still reviewing whether it would try to construct any new laterals to serve new customers as part of the project, and whether any of those would be located in Maine.

“It’s too early to tell,” Hanley said. “But when we built the original pipeline, we anticipated that 15 percent of what we transported would stay in Maine. Currently, 50 percent stays in the state of Maine.”

Residential customers are the largest consumers of natural gas in New England. Of the 2.3 million natural gas customers in the region, 2.1 million are residential users, according to a market update published in February by the Northeast Gas Association. Commercial and industrial customers for natural gas total about 236,000.

That survey, however, noted that power generation is the leading growth sector for gas consumption in New England and New York.

Although the company plans to tie the pipeline to LNG plants proposed in Canada, Hanley stressed that the pipeline would not be transporting liquefied natural gas.

Natural gas is liquefied by cooling it to minus 260 degrees Fahrenheit. It is usually transported by tankers to a terminal and off-loaded into large tanks. The LNG is drawn from the tanks and heated so it returns to a vapor state.

The LNG would go through that process before it enters the Maritimes pipeline, according to Hanley.

Maritimes had planned a smaller expansion project that would have included a new compression station in Washington County along with some additional looping. The company canceled that project after a drilling project in Canada failed to produce the anticipated amounts of natural gas.