CONCORD, N.H. — A seven-year battle over the Northern Pass transmission project takes a critical step forward Thursday when a hearing at the New Hampshire Site Evaluation Committee begins on the $1.6 billion plan to bring power from Canada to markets mostly in southern New England.

What you need to know:

WHAT IS NORTHERN PASS?

First conceived in 2010, the project calls for building a 192-mile transmission line in New Hampshire from Pittsburg to Deerfield, carrying enough Hydro-Quebec power to southern New England markets to power about a 1.1 million homes.

It is one of several projects in the Northeast that is hoping to tap hydro power in Canada to supply the growing demands for power from the likes of Boston and Hartford, Connecticut.

Northern Pass also hopes to take advantage of expected demands resulting from a law that requires Massachusetts to solicit long-term contracts for 1,200 megawatts of renewable energy, including hydropower, onshore wind and solar power.

CHEAPER ENERGY

Supporters, including New Hampshire Gov. Chris Sununu, argue the project will help address the state’s and region’s sky-high energy prices.

The Northeast has the highest energy prices in the country at 16.33 cents per kilowatt hour – compared with 10.15 per kilowatt hour nationally. Politicians across New England have argued that is one reason why businesses are leaving states like New Hampshire.

If approved, Eversource has said it would result in an annual reduction of $62 million to residents and business customers in the state and about $600 million to $700 million annually for New England – a number critics have said is inflated.

AWFUL ViEWS

Opponents, who have filed several lawsuits over the project, argue the towering transmission lines – as high as 155 feet – would ruin the scenic views in the state’s northern region and hurt the tourism industry.

More than two dozen towns, including the capital, Concord, have come out against the proposed project.

Environmental groups, such as the Society for the Protection of New Hampshire Forests, argue it would destroy property values and harm the environment.

Many have said they would support the project if all the transmission lines were buried. The company amended its proposal in 2015 to include the burial of 60 miles of the line mostly around the White Mountain National Forest.

It argues that burying the lines entirely would raise the cost by $1 billion, making the project economically impractical.

WILL IT BE BUILT?

Should the Site Evaluation Committee approve the project later this year, it still would needs a presidential permit from the U.S. Department of Energy since the project crosses national borders.

The company expects to get that permit but there remain doubters, especially since a Department of Energy draft environmental assessment of the project in 2015 concluded it would do irreparable damage to New Hampshire’s scenic beauty, the environment and property values along the route.

There also are other proposed projects that some environmentalists say would be less visually disruptive.

In Maine, the Massachusetts-based Anbaric Transmission is proposing a 300-mile transmission project that would bury cables from eastern Maine and then under the ocean to deliver power to Massachusetts.

In Vermont, National Grid is seeking to run a 60-mile line partially under Lake Champlain that would connect to the existing regional power grid in New Haven.

Eversource says more than 80 percent of its Northern Pass project is either underground or be built within existing right of ways.