There’s 3.3 micrograms of Uranium in every litre of seawater and since there’s 1.35 exalitres (1.35E+18 litres) of seawater, thus there’s about 4.5 trillion kilograms of Uranium for anyone who wants it bad enough.
As Uranium, when fissioned, produces about 90 trillion joules per kilogram, that means there’s 405 million exajoules of energy potential in the ocean. One terawatt expended over a year is 31.5576 exajoules, thus the ocean’s energy store is 12.8 million terawatt-years. Humanity is presently using 15 terawatt-years per year so if all our energy came from Uranium it’d last 856,000 years at present energy levels.
But what’s in the sea must come from somewhere – about 64,000 tons of dissolved Uranium flows into the sea every year, eventually being removed by chemical reactions in the seabed after floating around for ~70,000 years on average. If we could remove 50% of the annual flow – in energy terms 90 terawatt-years – we would have an ever-renewing resource, naturally.
An affluent Westerner in the USA or Australia, uses about 10 kilojoules of energy per second. Thus 90 TW-years would supply 9 billion people with a Western energy-rich lifestyle and that much energy supply is essentially available for billions of years.
Could humanity last so long essentially static in population? That’s a question no one can yet answer, but at least we know they’d still be able to live well a billion years from now if we get the social equations right.
Hi Folks;
Note the following link for a brief summary of research being done to reduce Tokamak fusion reactor plasma instabilities.
http://blogs.physicstoday.org/update/2009/05/spinning-fusion-plasma-to-stab.html
With ~ 10 EXP 17.5 metric tons of hydrogen locked up within our hydrosphere, we could power human civilization for about 10 EXP 15 years.
Note also the presence of Thorium and other fuels that could be bread in breeder fission reactors to produce lots of extra fission fuel.
Now the Sun will expand into a Red Giant star in about 5.5 billion years so perhaps the above calculations are not too realistic, but I like to muze that if the universe is infinite in extent, then from a philosophical and mathematical perspective, we have an infinite amount of nuclear fuel at our disposal and by corollary, an infinite amount of energy to be able to evenetually collect as the mathematical limit of human civilization life time approaches infinity.
It is any ones guess as to whether or not we humans will cause our selves to go extinct, however I am mindful of one former U.S. military General’s statement regarding the development of the hydrogen bomb that we have progressed to the point were we have harnessed and mastered the source of cosmic energy.
With so much fusion fuel available within the universe, and fission fuel locked up within the confines of planets, it seems as though the fuel is just begging us to reach out into the cosmos and sequester it.
If protons and electrons turn out to be stable, then perhaps hydrogen will be available forever, perhaps even long after the expansion of space time and perhaps other space time effects deplete the energy available from the zero point field characteristics of space time and perhaps long after the cosmological constant, if it exists, wanes to useless levels of energy density. The caveat to this depletiong is of course the condition that these two sources of potential energy actually decline in density as the universe expands.
Hi James
I used to go along with Frank Tipler’s idea of a collapsing Universe being manipulated for infinite energy by Life, and while I don’t think that prospect has changed, I am not so sure it’s the only way for Life to continue. Yet if there’s eternal inflation and other accessible regions of the “multi-verse” that we’re just a tiny bit of, then why haven’t other Intelligences bridged between the different domains and colonized this one? The eternally self-renewing cosmologies of Steinhardt and co. are fundamentally depressing because Life doesn’t (obviously) dominate the evolution of the Universe and is destined for eventual termination.
I’m hoping we know far less than we think we do and the Cosmos has surprises ahead.
Hi Adam;
See the interesting article on liquid flouride thorium reactors at
http://www.dailykos.com/story/2008/3/16/037/54953/271/477737
The website looks as if it might be a little radical but the story on the reactors is interesting.
By the way, I came up with some texts that you might be interested in although I still have not found my copy of my favorite classical mechanics text. I provided Amazon.com links to other texts including another classical mechanics text that I also used in college. This additional text I found was somewhat difficult for me to study quickly because the nomenclature used by the author was a little different from that which is commonly used in the textbooks I used throughout my academic career. I posted these links as followup comments to your inquiry about textbooks on my website.
I am still looking for my copy of my favorite classical mechanics textbook. If I do not find it this weekend I will email my former professor to determine the respective title, author, and addition. I really found this text to be one of the best texts I have ever worked with and it does cover some relativistic classical mechanics.
Regards;
Jim