Up to 800 jobs could be created over the next 15 years at the Grangemouth site, according to a long-awaited report.
The Project Willow study, by consultants EY, sets out nine areas where there are potential opportunities for green industries at Scotland's only oil refinery site, which employs around 2,000 people.
The £1.5million feasibility study, which was funded by the UK and Scottish governments, said it would require £3.5billion of private investment to create jobs in areas like sustainable aviation fuel, hydrogen production and plastics recycling.
The refinery at the industrial complex on the Firth of the Forth is being shut but its owner Petroineos, resulting in the loss of 400 jobs.
Scottish First Minister John Swinney said: "Grangemouth is home to over a century of industrial expertise and employs thousands of highly skilled workers, placing the site at a massive competitive advantage and creating a unique opportunity for investors.
"Everyone working at Grangemouth's refinery - and in the wider industrial cluster - is a valued employee with skills that are key to Scotland's economic and net zero future."
