The Australian Energy Market Operator's new 30-year roadmap for the national electricity market identified HumeLink as one of five major transmission projects which should be progressed "as urgently as possible".

The Transgrid project involves building about 360 kilometres of power lines through southern NSW, forming part of a transmission "superhighway" along the east coast.

It would also connect Snowy 2.0 to the national electricity grid, although that isn't set to occur until the end of the decade after Energy Minister Chris Bowen confirmed reports that the project had suffered an 18-month delay.

Transgrid had been aiming to complete HumeLink in late 2026, as the proponents need to clear various approval processes, acquire land along the route and construct the transmission lines before it's up and running.

The project faces community opposition, including from action groups who want the transmissions lines to be built underground.

The market operator's roadmap calls for the project to be online in July 2026, helping to shield consumers from any earlier-than-expected closures of coal generators around that time.

Transgrid chief executive Brett Redman told The Canberra Times that the earlier timeframe was achievable.

"We're going to lean into that [July 2026 date] and maybe even a little better if we can," he said.

"The reason for that is the market is going to need the benefits of these projects sooner rather than later with all of the rapid change that is going on."

Transgrid earlier this year settled on a preferred 200-metre wide corridor where the powerlines would be built along the route. The corridor is set to narrowed to 70 metres after talks with landowners.

The company would have to acquire land, meaning compensation for landowners.

Mr Redman accepted that compensation wouldn't "solve" everything for landowners who had a deep connection to their property.

"It weighs heavily on us the challenge of that [choosing the exact route], but what we can't do is say 'we're not going to do the project' because the bigger community needs it," he said.

"So with that in mind, we do our honest best around the route selection to minimise the impact and harm while then acknowledging the very real impact it has on people wherever we pick."

Mr Redman said the "vast majority" of funding for the project would come from Transgrid shareholders and banks, although it would seek some federal government help, likely in the form of a loan.

Mr Bowen on Thursday said the federal government would invest in HumeLink and the other priority projects via its $20 billion "rewiring the nation" plan.

Andrea Strong is part of the HumeLink Alliance group, which wants the transmission lines to be built underground to protect the landscape.

"As we need more transmission, as we transition our electricity supply from fossil fuel to renewables, our landscapes can't be a casualty," she said.

"Countries overseas have come to the conclusion that undergrounding transmission is the environmentally responsible solution."