Northern Pass paid $2.35 million for a key parcel of property in the city of Franklin, laying out more than three times what the property is valued for tax purposes.

On Thursday, Northern Pass subsidiary Renewable Properties Inc. purchased the 118-acre Thousand Acres Campground on Route 3, according to Merrimack County property records accessed online.

Northern Pass spokesman Martin Murray said the land will serve as the terminal, where DC power from high-voltage transmission lines will be converted to AC power.

The property is located at a junction of the state’s energy grid, he said.

“From an energy way perspective, it was a logical spot to locate the terminal,” Murray said.

The property is valued at $653,000 for tax purposes, Mayor Ken Merrifield said Monday.

“Evidently, it’s worth that much to them,” Merrifield said.

A partnership between Northeast Utilities and NSTAR, Northern Pass is a $1.1 billion project that would provide up to 1,200 megawatts of electric power from Hydro Quebec to New England. The electricity would travel along more than 180 miles of power lines from the Canadian border at Pittsburg to Deerfield.

The line is in the early stages of obtaining federal and state permits.

Franklin is key to the project. The terminal is expected to cost $250 million to build; its construction will employ hundreds.

Merrifield said the vast majority of Franklin citizens support the project, and he called it the greatest economic event in the city’s history.

“It (the purchase) is a sign that the folks in charge of the project are confident of the ultimate outcome of the permitting,” Merrifield said.

“We’ve very optimistic the project is going to go through,” Murray said.

Murray said the owners of the campground, Robert and Marion Kolbe, contacted Northern Pass several months ago.

About 30 to 40 acres of the Thousand Acres spot will be used for the terminal operation. Murray said there are no plans to develop the remaining property, and Northern Pass does not need to purchase nearby property for transmission lines.

Murray would say little about efforts to acquire rights and property for transmission towers in northern New Hampshire.

“We’re not ready to announce a new preferred route in the North Country,” he said.

He said the company hopes to announce a new route sometime during the first three months of 2012.

“We don’t have a new route yet. It’s going to be shaped by the completion of the effort up there,” Murray said.