[ETH_start]

Breeder reactors are extremely fuel efficient. The cost is in building an actual breeder reactor itself, as it is an experimental technology. And the cost is not "widely prohibitive". The Wikipedia page says they are 25% more expensive than non breeder reactors.

[defrost]

Breeder reactors have no bearing on the costs of primary mineral extraction from the crust - it's a seperate line of discussion altogether to this sub thread.

Perhaps you intended your comment in reply to someone discussing the pros|cons of fuel generation via breeder reactors rath than to my comment which addresses the inevitable rising effort required to extract more resource from the crust (or ocean) over time.

[ETH_start]

The comment you initially responded to was asking about the cost of breeder reactors:

"It might be cost-prohibitive now, but is there any reason to think that it can't get cheaper?"