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."

Ministers say it is necessary so police and security services can access the data they need after a legal ruling which declared existing powers invalid.
The proposed law has the backing of Labour and the coalition parties.
A special cabinet is being held to agree the planned laws, which will only last until 2016.
Prime Minister David Cameron and his Lib Dem Deputy Prime Minister Nick Clegg will tell a special cabinet meeting on Thursday that emergency legislation is necessary to keep the country safe.
A recent ruling of the European Court of Justice has removed the obligation on telecoms companies to retain records of when and who their customers have called, texted and emailed.
Without a new law Mr Cameron and Mr Clegg will claim that that information could be destroyed within weeks by companies fearing legal challenges.
Labour is backing emergency legislation after all-party talks agreed that this law would enshrine existing rights and not be used to extend them by re-introducing the so-called "snoopers charter".
It will also bring in so-called safeguards including:
Critics will no doubt argue that the time for that debate is now. To pass any new law in just a week is rare. So too is it to have the backing of all three main parties even before it is published.
On a subject as sensitive as giving the police and security services access to phone and internet data this is bound to be controversial.
Update 08:45 BST: The emergency legislation will oblige telecom firms to retain data for 12 months. Under the European law which it replaces companies could be asked to retain data for 24 months.
More controversially the new law will also produce what is being described as a "clearer legal framework" to allow access to the content of calls, texts and emails after a warrant is signed by a senior government minister. Telecoms companies are said to have warned ministers that after the Edward Snowden revelations they are vulnerable to legal challenge by their customers.
The Labour MP Tom Watson has condemned the plans as a "stitch up" which prevent MPs from considering the legislation properly.
Plans to build a £200m tidal barrage in Lancashire that will power tens of thousands of homes have been announced.
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Emergency legislation will be brought in next week to force phone and internet companies to log records of customer calls, texts and internet use.