That is not renewable, it's just a very large source of non-renewable fuel.
Of course it will run out eventually but so will the sun, in a similar amount of time.
> Although the concentration of uranium is quite low, about 3.3 ppb (parts per billion) in seawater of average oceanic salinity, the amount present in the total volume of the oceans is very great, some 4.5 billion tonnes. Of this, perhaps only that uranium contained in the upper 100 meters or so of the surface well-mixed layer should be considered accessible for recovery, some 160 million tonnes. Practically speaking, the amount contained in the ocean surface layers is unlimited with respect to large scale extraction in the forseeable future. This results from the replenishment by continental weathering and river runoff being much larger than forseeable extraction rates.
...
> 1) The surface waters of the oceans comprise a virtually inexhaustible uranium resource of some 160 million tonnes, extractible indefinitely at a rate of a few thousand tonnes per year.
Exxon Nuclear Company, "EXTRACTION OF URANIUM FROM SEAWATER: EVALUATION OF URANIUM RESOURCES AND PLANT SITING, VOLUME I", pp 6-7, 9, February 1979, https://www.osti.gov/servlets/purl/6191296
The above quotes are from the executive summary. Page 35 has the money quote:
> This represents an influx of about 9000 tonnes annually.
Which supports your contention that sea water CANNOT provide an endless supply considering that current annual consumption is ~90,000 tonnes, 10x the replacement rate.
EDIT: s/CANNOT NOT/CANNOT/
Anyway, in steady state the consumption from the oceans can be only equal to the inflow from rivers. If that's (as I've seen estimated) 25,000 tons/year, that's enough to power the world if breeders are used, but not enough if today's thermal burner reactors are used.
What's more surprising, actually, is how much uranium we consume currently. And AFAIU, we do so very inefficiently. Seems to me we'd get a much better RoI by using uranium more efficiently than by turning to seawater for more uranium to waste.
[1] Assuming it becomes viable in the first place. It certainly doesn't seem economically viable, today.
When the US was first making the switch from wood to coal as a principle fuel, in the 1880s, the argument in contemporaneous accounts was that a small fraction of the probable reserves of coal would serve all energy needs for millions of years, given that perennial caveat, at present rates of consumption.
What happened, of course, was that rates of consumption increased somewhat. Coal went from fueling a small number of structural heating, locomotion, and smelting uses to vastly expanded railroad, steelmaking, and most especially, electrical generation uses. Trainloads of coal arrive daily at power plants, still. Others are located at mineheads themselves as electrons transport more readily than lumps of fossilised tree. The Jevons paradox is a mighty bastard. By present estimates, again, at present values of consumption, coal reserves are estimated at 100-300 years.
At present rates of electrical energy generation, existing terrestrial (non-oceanic) uranium would suffice for fewer than two decades worth of energy use. When you factor in even probable growth due to:
- Extending Western standards of living to another five billions of the world's population.
- Expansion of total population from 7.5 billions to 11-12 billions.
- Continued "normal" economic growth at 2-3% per annum, that is, doubling every 25-30 years, roughly.
... the total energy requirements increase tremendously.
(Note that renewables also strain to keep up with such growth -- my sense is that the fact that incident solar power on Earth of some 7,000x present human energy consumption actually represents a dangerously narrow margin of safety.)
I'd worked out at one point the remaining reserves given some rate of projected annual growth, a fairly simple application of exponential math. The numbers are exceedingly sobering.
TL;DR: If there is some putatively nonrenewable fuel source whose reserves would extend to some point in time beyond the viability of some specified landmark (h. sapiens as a viable species, C3 photosynthesis on Earth, etc., variously a few million to about 800 million years), then the resource is not meaningfully constrained, and we can make reasonable use of it.
But given any notion of continued exponential growth, which is to say, a constant percentage increase in economic activity, given all available history, if not some putative but very-much-unproved virtualisation-of-activity hypotheses, that's a high bar to meet.
It feels like you're double-dipping here: I don't see how we extend "western standards of living to 5 billions of the worlds population" without concurrently extending the same GDP per unit of energy use to the same populations.
It's not like we all decide to just buy exponentially bigger houses and cars, for all that a look around certain parts of the US tend to suggest this in the near term. :-)
It also seems to me that a steady increase in GDP per unit of energy is a likely consequence of higher energy prices - while energy is dirt-cheap (and often subsidized), use tends to be profligate.
Less energy intensive, perhaps. But not less electricity intensive. As cars and trains go electric, electricity demand will increase. If we're going to make planes and ships hydrogen powered, that's going to be another big electricity demand.
Or more briefly: yes ;-)
- Economic policy, targets, and theory are currently expressed in terms of constant percentage economic growth. Which is to say, exponential growth.
- All empirical evidence ties past growth to increased resource consumption, most especially energy. "Dematerialisation" studies tend not to be well supported, and arguments for nonmaterial mechanisms for economic growth prove to be largely unfounded far more hypothetical or theological than even theoretical.
The point that extending Western standards of living beyond the ~1 billion residents of the US, EU, JP, CA, AU, & NZ (line noise), and the additional 1 billion of China who are still on net nowhere near Western levels of affluence, but have seen appreciable growth over the past two decades, accompanied by massive increases in energy consumption, resource utilisation, and sinks (effluent) exploitation, much of that energy from coal, to the five billions elsewhere, requires a similar energy-intensity-per-unit-GDP is precisely the one I'm trying to make.
There is some space for optimising efficiency in terms of GDP per unit energy, and within specific nations, there's been some evidence of this -- see the US since the oil shocks of the 1970s. But progress has been limited, most especially progress in the absence of further price shocks. Applying imposed efficiency requirements has worked poorly, and the tolerance of imposing, say, higher fuel taxes (as is practiced in Europe and Japan, neither having much by way of indigenous petroleum supply) has been scant.
(Higher prices for petroleum in petroleum-exporting countries themselves is even less viable, and is a major component of a theory of their collapse, the Export Lands Model. See Venezuela, Egypt, Syria, and Yemen as examples, with Russia potentially another, though its production has yet to fall markedly.)
Steve Keen has been doing some remarkable recent work on the role of energy in production functions, including a rewrite of the Cobb-Douglas production function to include energy as a term along with capital and labour. He's been working with a long-time researcher in the area, Robert Ayres, and making quite substantial progress, though whether or not that will be accepted by the field remains an open question. Economics has been exceedingly resistant to such messages in the past.
Keen's conceptual insight is that "labour without energy is a corpse, capital without energy is a sculpture". It's possible to increase efficiencies. Early steam engines operated in the 1-10% thermodynamic efficiency range, modern dual-cycle gas-turbine generation can exceed 50%, and when making use of waste heat for other processes can approach 80% efficiencies. But you're always limited to some theoretical maximum.
One area I've been exploring is the question of just what specific technolgical mechanisms there are. Economists describe technology generally as "efficiency", but it's an efficiency gained through specific means. I've identified nine:
1. Fuels. Applying more (or more useful) energy to a process.
2. Energy transmission and transformation.
3. Materials. Specific properties, abundance, costs, effects, limitation.s
4. Process knowledge -- how to do things. What's generally described as "technical knowledge", here considered as a specific mechanism of technology.
5. Structural or causal knowledge -- why things work. What's generally described as "scientific knowledge".
6. Networks. Interactions between nodes via links, physical or virtual, over which matter, energy, information, or some mix flow. (People would be one possible flow.) Transport, comms, power, information.
7. Systems. Constructs including sensing, processing, action, and feedback. Ranging from conceptual to mechanical to human and social.
8. Information. Sensing, perceiving, processing, storing, retrieving, and transmitting. Ranging from our natural senses to augmented ones, from symbolic systems (language, maths) to algorithms.
9. Hygiene. Sinks and unintended consequences, affecting the function and vitality of systems, and their mitigations or limits.
I've been playing with this ontology for a few years, and have yet to either remove or add to the basic nine factors. A dematerialisation that succeeded in doing so would be quite remarkable. I'm open to suggestions and criticisms.
2/3 of sunlight falls on the oceans, unlikely to be developed as technological solar farms. Marine environments are exceedingly harsh. You can also discount Antarctica. We're already down to ~25% of the grand total surface are, and hence energy.
Panel efficiency (~<20% typically), spacing factor (shaded panels generate no power), and further losses greatly cut into the remaining surplus. In net, ~1-10% of the resource might potentially be available. And other terrestrial ecosystem resources need their own cut.
There's still a possible surplus relative to present consumption, but the margins begin to look uncomfortably thin. Population growth and expansion of industrial standards of living cut further into that, as discussed up-thread.
Expressed as population, area, and energy, over time, the plots are interesting.
Jevons paradox is something that can happen, not a claim or proof that it always happens.
And exponential growth never continues. I mean, we can all agree Moore's law and population growth, that people irrationally thought would go on forever, are reaching their limits, right?
I agree that exponential growth cannot continue. However you'll find a matter of faith in mainstream economics that it can. Even severe critics, as Thomas Piketty, state this, as in this offhand passage from Capital in the 21st Century:
The median scenario I will present here is based on a long-term per capita output growth rate of 1.2 percent in the wealthy countries, which is relatively optimistic compared with Robert Gordon's predictions (which I think are a little too dark).
That's still doubling every 58 years.
The cornucopians are far more explicit and optimistic. Kahn & Simon, Maddox. Tom Worstall, here:
http://blogs.telegraph.co.uk/finance/timworstall/100017248/i...
A chief mode of expansion isn't in intensive use, that is, per person or concern (firm, agency, organisation), but extensive use: the number of individuals, concerns, and applications making use.
The access to artificial light by people, by entities, by activities, has exploded. More people have access. Lighted billboards, sport fields, indoor agriculture, vanity outdoor lighting, etc., etc., etc.
New York City's Broadway became known as The Great White Way in 1910 due to its spectacular use of electric lighting. That is now every populated hamlet save North Korea, and regions of central Africa, Amazonia, and Oceania, have comparable lighting levels outdoors.
https://www.spotlightonbroadway.com/the-great-white-way-0
https://eoimages.gsfc.nasa.gov/images/imagerecords/55000/551...
And that excludes interior residential, commercial, and industrial lighting.
Light pollution is now a thing.
https://www.nationalgeographic.com/science/2019/04/nights-ar...