When a consortium of big oil and gas companies says it wants to tear a 400-mile corridor through the state to lay pipe for transporting millions of cubic feet of natural gas every day, it is bound to draw opposition.

Some property owners have banded together to object to the line crossing their land, and local oil companies have disputed claims of the benefits of gas vs. oil. The Maine Green Party organization also is opposed to the development, specifically the speed of the permitting process.

But opponents of the project in general concede that much of the talk around the proposed pipeline has been driven by the potential economic benefits.

Yet the chairwoman of the Greens says many questions remain unanswered because nobody is asking them.

“There are 1,400 farms, businesses, homes and properties that this thing is going to permanently affect — for some it will be as close as 50 feet,” says Nancy Allen. “The issue is: How are people going to cope with this?”

While the Greens and others grapple with energizing opposition, the proponents of natural gas are raising the volume on discussion of their side of the story. Today at Husson College, a daylong symposium featuring a panel of industry executives and experts is expected to go into great detail on the role that the new energy supply will play in the lives of people and businesses.

It is a timely show of force for the consortium behind the Maritimes & Northeast Pipeline, which includes Duke Energy, Mobil Oil, and Westcoast Energy of Canada. This summer, the pipeline project will be in the final phase of preparation with hundreds of surveyors scattered across the state readying the site of the 400-mile corridor.

They are traipsing around wetlands, through forests and across back yards, flagging and mapping the line. Federal approval is expected later this month, pipeline officials say, and the state’s Bureau of Environmental Protection should wrap up hearings soon after. Construction of the line is expected to begin in the fall.

“The markets have quickly started to evolve,” says Brian Prenda, a spokesman for Maritimes & Northeast. “You’re seeing that here with the establishment of local distribution companies like Bangor Gas.”

When the consortium was set up in 1994, the group estimated that as much as 15 percent of the gas piped through the state en route from Nova Scotia to New England would stay in Maine. Today, with a dozen gas-fired power plants on the drawing board, and at least three local natural gas distribution companies vying for new customers north of Portland, the estimate is up to 30 percent.

The ambitious efforts of the gas distribution companies have raised hackles among the state’s oil dealers, though. Countering claims of the benefits of natural gas to the average business or homeowner, oil dealers have gone so far as to run ads questioning the price plans of newly formed companies such as Bangor Gas.

The Bangor Hydro-Electric Co. subsidiary has the state’s approval to go ahead with plans to lay pipe around the Bangor area and tap into the Maritimes & Northeast Pipeline’s main line when it is completed next year. Several oil dealers are saying that, despite claims to the contrary, oil is still as efficient for both heating and industrial uses and is, on average, cheaper.

“Natural gas is not the great salvation,” says Richard Hawkins, the president of Hamel Fuels of Brewer.

Oil dealers such as Hawkins like to use the city of Lewiston as an example. Along with Portland, it has had natural gas for years but has lagged behind state economic growth averages. Members of the panel pulled together by Husson College for the symposium counter that the importance of gas needs to be measured from the perspective of choice.

“From a mix point of view, it’s important to have it,” says Dr. Michael N. Conlon, chairman of Bord Gas Eirann in Ireland. “It does create a great economic buzz.”

Since being discovered off the coast of Ireland in the early 1970s, natural gas has captured about 20 percent of the Irish energy market. Of course, Ireland’s economy has been growing while, for the Maine economy north of Portland and away from the coast, there is little to support the addition of new players in the energy business.

If companies such as Bangor Gas are to succeed, they will do so most likely at the expense of the old established oil distributors.

“We are actively seeking new customers in 60 Maine communities,” says Clark Irwin, a spokesman for Central Maine Power Co. which, like Bangor Hydro, has set up a gas subsidiary. “Things seem to be moving along rapidly.”