A Labour government would invest in a £3.5bn tidal power project on Merseyside, leader Jeremy Corbyn has said.
Making the announcement on a visit to Liverpool, Mr Corbyn said it would tackle the north-south divide and address climate change.
The party said the project would be funded out of existing commitments set out in their 2017 manifesto.
The BBC has approached the government for a comment on the project's funding.
Plans for a tidal project, put on hold in 2011, were revived by Liverpool City Region Mayor Steve Rotheram in 2017.
Mr Corbyn said the project would "kick-start Labour's green industrial revolution".
In May, Mr Rotheram said the city region was moving forward with plans to harness tidal power.
He said the "unique geography" of the area made it one of the only places in the UK with the potential to generate "plentiful, predictable, green tidal electricity".
The plans involve harnessing the energy of the River Mersey to produced renewable energy.
It would use a series of underwater turbines would be turned by the natural fall and rise of the tide.
The combined authority said it could power up to one million homes and create thousands of job.
An outline business case is currently being worked on to provide an evaluation of the project's viability and is expected to be completed next year.
The Department for Business, Energy and Industrial Strategy said while it recognised the "potential of marine technologies" as part of the work towards net zero emissions by 2050", any new funding proposals "must demonstrate strong evidence of value for money for consumers and taxpayers".