Ted Re...Fission uses pure U-235......best estimates are there is a 35-40 year supply. Breeders would lengthen that usage period considerably but they are unstable and no one wants to fool with them.
Man, I can't believe how close you were with that guess. You were only off by 5 billion yrs, not 50, 500, 5 mln, or 500 mln, but really 5 billion yrs. I don't plan on living that long.
How much uranium is there in seawater?
Seawater contains 3.3x10^(-9) (3.3 parts per billion) of uranium, so the 1.4x10^18 tonne of seawater contains 4.6x10^9 tonne of uranium. All the world's electricity usage, 650GWe could therefore be supplied by the uranium in seawater for 7 million years.
However, rivers bring more uranium into the sea all the time, in fact 3.2x10^4 tonne per year.
Cohen calculates that we could take 16,000 tonne per year of uranium from seawater, which would supply 25 times the world's present electricity usage and twice the world's present total energy consumption. He argues that given the geological cycles of erosion, subduction and uplift, the supply would last for 5 billion years with a withdrawal rate of 6,500 tonne per year. The crust contains 6.5x10^13 tonne of uranium.
He comments that lasting 5 billion years, i.e. longer than the sun will support life on earth, should cause uranium to be considered a renewable resource.
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