Pembroke could host an experimental nuclear fusion reactor if the council backs plans for a site by the Valero oil refinery.
Pembrokeshire council will be asked 17 May to support the project, which it is hoped could create limitless energy.
The application must meet strict criteria and the site will have to be included on a list of candidate sites.
Vale of Glamorgan council is bidding for it to be built at the Aberthaw power station site.
The UK government has set aside £222m to produce a design concept once a site has been identified.
Communities had until the end of March to nominate locations.
According to Pembrokeshire council documents: "Fusion energy is turning the process that powers the sun into carbon-free, safe and abundant electricity for a cleaner planet."
It said it was sometimes called the "energy holy grail" as it should release "vast amounts of energy from a very small amount of fuel".