Grangemouth Scotland, Project Willow
About 480 jobs could be created with the manufacture of e-methanol for jet fuel and e-ammonia for shipping.
But that would require £6.6bn of private investment and would not be operational until around 2035, the report said.
Plastics recycling could be done much sooner, within five years, at a cost of about £600m. It is estimated around 250 jobs could be created.