In reply to Jed Rothwell's message of Tue, 9 Jun 2015 20:59:39 -0400: Hi, [snip] ><[email protected]> wrote: > > >> >0.170 ppm. Granted, it is a lot more abundant than copper, nickel, gold or >> >palladium. >> >> At the current rate of World energy usage, and assuming only 33% conversion >> efficiency (i.e. 6 MeV / Li atom), that would last us for 34 million years. >> > >Do you mean that is how long the supply in the ocean would last?
Yes. >That is >not a valid method. As you extract lithium from the ocean and the >concentration goes down, it would get harder and harder to extract more. True, but it would be 17 million years before it was twice as difficult as now, and I don't think that twice as difficult would be a real impediment. Consider that they are already looking at ways to extract it that would be economically viable at the current Lithium price, or a bit higher, while the energy value of the Lithium is something like 22000 times higher than the actual cost of the metal (assuming a value for the electricity of 5 cents / kWh). In short extraction of the metal to be used as a fusion fuel would be cheap enough to extract almost all of it, and that's just using technology that we know about now. Besides, the concentration in the rocks and soil is abut 20 times higher than in sea water, so we may end up just extracting it from the ground rather than from sea water. (Whichever is cheaper.) Furthermore, I think that if we don't have full control over all kinds of transmutation reactions in 17 million years, then there is little hope for humanity. Other transmutation (fusion) reactions would deliver energy for trillions of years (not a typo), by which time the Earth would long have been swallowed by the Sun anyway. (There is much more energy in the Deuterium content of water, and also in the Boron content of sea water, and these are just the easy ones. The H content would last thousands of times longer than the D content.) >It isn't as if you move all the water in world from one bowl to another as you >extract the lithium. I guess you would start to see a decrease after a >million years or so. > >By that time, extraterrestrial sources should be available. Heck, I expect >they will be available in a few hundred years, or sooner. I hope that all >extraction and manufacturing moves off-earth, with delivery by space >elevator. Or by anti-gravity flying machines. Something quiet, and much >safer than rockets. > >- Jed Regards, Robin van Spaandonk http://rvanspaa.freehostia.com/project.html
