The cable - estimated to cost between $1.3 billion and $3.1 billion - would secure energy and lower power prices for the nation's eastern seaboard, the Tasmanian Chamber of Commerce and Industry chief executive said at a project briefing in Burnie on Wednesday.

"Project Marinus is an absolutely critical piece of infrastructure, not just for Tasmania, but for the nation.

"It will bring power prices down for the nation and set us (Tasmania) up for 30 years at least of significant development, most of it in the North-West."

He said the second cable and the extra wind generation and pumped hydro projects it was expected to underpin would be "amazing for the state"

"We're looking for both sides to commit to this project leading into the federal election."

The Morrison Government recently committed $56 million towards speeding up the planning and approvals process for the Marinus Link, a move supported by federal Labor.

At the function, Energy Minister Guy Barnett announced Hydro Tasmania had confirmed three sites had been identified as the most promising for pumped hydro developments.

"The sites at Lake Cethana and Lake Rowallan in the North-West and near Tribute Power Station on the West Coast will now undergo an intensive feasibility study and community engagement process, costing up to $30 million," Mr Barnett said.

"The Tasmanian government and the Australian government have committed to progressing the first of these sites to a final investment decision, subject to final commitment to the second interconnector.

"An estimated 300 to 400 local jobs are expected during the construction phase."

Hydro said the federal government committed the $56 million following the release of an initial feasibility report "demonstrating that the business case for a second Bass Strait interconnector stacks up".

It said pumped hydro would introduce new capacity into the system, inject significant investment into regional areas and create jobs.

Chief executive Steve Davy said it was an exciting time for Tasmania.