Natural Energy Wyre Ltd said the Duchy of Lancaster has given it an exclusivity deal to create the UK's first tidal energy power station.
If approved, it will be built on the Wyre estuary, which belongs to the Queen in her role as Duke of Lancaster.
The Royal Society for the Protection of Birds said it had concerns about how the scheme could affect wildlife.
Natural Energy Wyre Ltd said it now needed to find £10m to proceed with a formal planning application.
It said the power station would support the government's renewal energy objectives, create thousands of jobs and attract 600,000 visitors to the region, as well as help with flood defences.
A barrage, which would span the mouth of the river with six turbines, would take three years to build, the firm said.
It will produce renewable energy four times a day, on the turn of the tide, for more than 100 years, Natural Energy Wyre Ltd added.
Graeme Chalk, head of project management for the Duchy of Lancaster, said the tidal barrage would "provide a source of green and affordable energy for many years to come".
Tim Melling, RSPB senior conservation officer, said: "Climate change is the biggest threat to the natural environment so it's vital we invest more in renewable energy. But tidal barrages are not the right option and this proposed scheme on the Wyre would cause major damage to the estuary.
"A barrage would knock the tidal system out of sync and destroy this prime feeding habitat by reducing the size of the feeding areas and making them available for less time."
Plans to build a £200m tidal barrage in Lancashire that will power tens of thousands of homes have been announced.