Pulverizing hard rock has an energy cost near 50 kWh per tonne if it is to fit 80 percent through 25-micron holes; half as much if the holes are 100-micron. Uranium yields 54 kWh of electricity per gram in the CANDU reactors nearest me, so if only 1.08 grams per tonne can be extracted, it might all go to power the crusher. Average rock is 2.2 to 2.8 grams per tonne, so it probably can yield a little net energy in this case. There is about as much CANDU-accessible fission energy in the average underfoot rock as there is tar combustion energy in the Alberta tarsands, and that energy is two-thirds net or more.

Seawater extraction of uranium definitely yields a very high net energy fraction, because nothing laborious need be done to the water; it could be considered pre-crushed. The uranium price at which this was expected to pay in 2001 was briefly surpassed recently, but now prices have settled back down. The rate of discovery of very cheap uranium in Australia in 2007 was nearly equal, in thermal terms, to the whole world's rate of petroleum burning.

How shall the car gain nuclear cachet

Physicist Michael Dittmar showed this in his ASPO VII presentation (slide 12):

Fantasies about uranium from sea water (concentration 3 mg/m3):
often claimed extraction cost: 200 dollar/kg (at most 1000 dollar/kg??)

Fact is: A single huge multi million(?) dollar experiment running over
many months claims to have extracted about 1 kg of uranium from sea
water. No follow up or control experiment has been performed so far!

1 GW(e) conventional reactor “burns” about 6 grams of uranium/sec
! “extract” uranium from about 10000 m3/sec (20% efficiency)!
Rhine river discharges on average about 2000 m3 per second!

! Good luck!

With desalination becoming more common in some parts of the world I have wondered wether mineral extract from sea water could piggy back on this?

As the minerals are concentrated in the brine from desal plants would it not be more viable to attempt extraction from this water?

Lets ignore seawater for a little bit; The energy cost of the rossing mine in nambia is 1/500th the energy returned in light water reactors from the uranium mined, and the ore grade is 300ppm.

Then consider that breeder reactor regimes are 200 times as fuel efficient than light water reactors.

The energy from mining uranium will never be a showstopper in nuclear power production.