You’ll need a heck of a lot more than restaurant oil for biodiesel. You’d have to collect crop leavings from across the entire country. And that would use up a vast amount of power right there, just in transport.
Coal could get us through a few hundred years. Nuclear will be the answer once they solve the waste problem.
Stranger had it right - you have to beam the power down via microwaves. And he’s probably right about the problems with that.
Re solar winds - they have to be accounted for, but you have to remember that everything in the system is in orbit around something. So if you were shielding Venus, you could have a set of large mirrors orbiting Venus. When they are coming around Venus and approaching the Sun, the solar wind is killing their orbital velocity around Venus, when they are around the other side the solar wind is adding to their orbital velocity. Get it right and it all balances out.
Can’t answer your restaurant question, but I’m not convinced by the biodiesel naysayers. Biodiesel, like all biomass proposals, is solar power. If we seriously want to use solar power for energy then we have to consider commiting land area similar to the amount we used for agriculture. We’re not talking about replacing current agriculture with biodiesel - we’re talking about massively expanding current agriculture so that we can meet our biodiesel needs.
Of course, it may be more efficient to cover a desert with heliostatic solar power stations and use the energy to run battery-powered vehicles, rather than try to grow biodiesel in the desert. Biodiesel requires a fair bit of processing from oil seeds to fuel - it may make more sense to grow trees and burn them in power stations (gasps of horror from the ultragreens, but it’s carbon-neutral) and again drive battery vehicles.
In all seriousness, I don’t know why people call Nuclear non-sustainable. Disregarding breeders, and re-using waste, (using some back-of-the-envelope calculation, if you want I can work it out in detail) there is more uranium on earth to produce 5-7 orders of magnitude more energy than all estimated remaining fossil fuels (even by very conservative estimates). A really good chunk of that Uranium is almost pure and ready to be mined. (Most of it is not as easily extracted, but even then). Uranium shortage is not a forseeable problem for many many many generations even if we go all-nuclear. It’s about as “sustainable” as solar (you know, that big nuclear fusion powerplant we orbit that is eventually going to run out of fuel and kill us all too). Safety, waste disposal, etc. are all pretty much solved problems by now.
Do you have a decent cite for that? I’ve heard the exact opposite claim made by an anti-nuclear spokesman on the radio - that if the world went 100% nuclear, we’d run out of uranium in a few years. Then again, I’ve also read that a tonne of granite contains enough uranium to make it an equivalent energy source to 50 tonnes of coal.
A correction to my previous post about solar winds - the vast majority of the force experienced by an orbiting mirror is from the pressure exerted by sunlight , not from the solar wind.
You can do the calculations yourself.
“One ton of natural uranium can produce more than 40 million kilowatt-hours of electricity. This is equivalent to burning 16,000 tons of coal or 80,000 barrels of oil.”
http://web.ead.anl.gov/uranium/guide/facts/index.cfm
“total Uranium resources total just over 4 billion tonnes”
www.nea.fr/html/pub/newsletter/ 2002/20-2-Nuclear_fuel_resources.pdf
For a quick back-of-the envelope calculation we’ll just equate tons and tonnes. Close enough.
16, 000 tons of coal for every ton of U.
4, 000, 000, 000 Tons of U.
= 64, 000, 000, 000, 000 tons of coal equivalent. 64, 000 Gt
“Coal resources… surpass 10,000 Gt”
geosci.uchicago.edu/~archer/ EnvChem/rogner.1997.fuel_reserves.pdf
64, 000 Gt of coal equivalent -10,000 Gt = 54, 000Gt Uranium remaining, 0r 86%.
86% of 4 Gt = 3.44Gt
80, 000 barrels of oil for every ton of U.
3, 440, 000, 000 Tons of U.
=275, 200, 000, 000, 000 barrels of oil equivalent. 275, 000 GB
Oil resources are just over 2, 600, 000, 000, 000 barrels
Gas just over 2, 200, 000, 000, 000
http://pubs.usgs.gov/dds/dds-060/ESpt5.html
Total oil and gas resources = 4, 800, 000, 000, 000 barrels. 4, 800 GB
275, 000Gb – 4, 800 = 270.2 GB remaining. Or 98%
98% of 3.44Gt = 3.37Gt
3.37Gt of Uranium remaining after accounting for all the world’s fossil energy resources out of an initial 4gT. Or 15% of the world’s U will account for all the energy in the fossil fuels.
So a 7 fold increase seems about on the money.
Of course this doesn’t take into account non-conventional oil. But let’s assume that tar sands, shale oil etc are equivalent to 50% of all of the combined energy output of liquid oil and coal combined. That’s a ridiculous claim but let’s run with it. That means that fossil fuel energy will equal a grand total of 22% of the energy available in Uranium.
So saying that Uranium will produce 5-7 times more energy than all the fossil fuels is being conservative.
That’s without utilising fast breeder reactors. If we factor them in then we can multiply the fissionable Uranium resource by around 100 fold and Uranium will yeild about 500 times more energy than fossil fuels.
All dependent of course that my quick calculations a contain no serious errors.
Nice work. Thanks!
I understand India is working to develop thorium breeder reactors, which I guess extends the nuclear reserves even more.
Because we’re using uranium up faster than it is being made. That’s what sustainable means, won’t run out. Saying solar power is not sustainable because the sun will eventually die is just silly.
SoaT has it right, as usual. Of the “alternative” energy sources only solar can produce the amounts needed, but it is roughly 5 times the cost of fossil fuels right now. Our only real option is to stop using fossil fuel we don’t actually need to until we can get solar cheap enough to be viable. Until then the easiest and most viable option would be to only manufacture diesel cars and low-sulphur diesel fuel.
How about this one. Of the 4,039,110 tonnes of Uranrium mentioned in your cite, 4,000,000 are listed as “Unconventional sources, recovered from seawater”. Another 22,000 tonnes are “Unconventional resources, recovered from phosphates”. Who knows what the cost of recovery of these unproven, unknown sources are*, but take them away and you’ve just lost over two orders of magnitude right there, you’re down to 17,110 tonnes - which include undiscovered and speculative sources. Known resources are less than 4,000 tonnes.
- “At present, only laboratory scale quantities have been extracted and as yet the cost to extract uranium from seawater is estimated to be very high, approximately five to ten times the cost of conventionally mined uranium. This technology would require additional time and investment to bring to deployment. Given the current low cost of uranium, with low-cost resources sufficient for several decades at current demand rates, it is doubtful that any significant funding will be made available in the foreseeable future”
Why is the one silly, and the other one isn’t? ‘Nuclear power is non-sustainable because we’ll eventually run out of fuel. Solar energy is sustainable even though we will eventually run out of fuel.’
Of course, the sun will last another five billion years. Uranium won’t. Just pointing out that in a very long time there will be no suns in the universe. Entropy, y’know. So given a long enough time line, there are no sustainable sources of energy.
But consider that the current-version human has only been around for – what? 25,000 years or so? Will we even exist in another 25,000 years, let alone a million?
This could lead to the unfortunate James Watt School Of Conservation: ‘We won’t be here, so let’s use it all up while we can!’
As I said before, I think we should use nuclear power because it is the most reliable source of non-fossile energy we have today. And we should develop other sources such as solar, geothermal and wind energies as appropriate to their locations.
Yes, but we know for certain that we can recover Uranium from seawater, phosphates etc. at a net energy yeild. The precise financial costs are unknown but there’s no doubt that they are energetically profitable. And that is all we are discussing.
If we accept this criticism then the same thing applies to the figure used for fossil fuels. If we remove the figures for unproven reserves and resoucres for coal, oil and gas then we lose over 75%.
That actually makes Uranium look even better.
There’s a distinction here to be made between “sustainable” and “renewable”. Biofuels, for instance, are renewable, in that they can be replaced by natural processes without net loss. Biofuels are not necessarialy sustainable, though, in that they probably cannot provide for the demand for current and predicted future energy needs.
Fissionables, like uranium and processed transuranic elements are sustainable, in that they will be able to provide for our energy needs for the foreseeable future. By the time we’ve run through the available quantities of uranium (assuming that energy demand doesn’t increase exponentially) the technology will have sufficiently advanced that we’ll have some kind of viable replacement, such as nuclear fusion. (Though that claim is entirely speculative; despite over half a century of active research we’re still the promised “twenty years away” from controlled, energy-generating fusion, but I think we can safely assert that we will have developed and matured the technology in the couple of centuries it will take to use up our fissionables.) Also, fissionables are available in great quantities in near-Earth and astreroid belt space; again, it is beyond our means, currently, to retrieve and process them, but in time we can have this ability; at least, if we don’t leave up to NASA to figure out. :rolleyes:
There are other reasons to reduced use of fossil fuels; aside from pollution (not only from combution byproducts but extraction, transportation, and processing), we’re going to need petroleum for the foreseeable future; even if we’re all driving fuel-cell personal automobiles, diesel fuel engines are necessary to provide the high torque, large output engines necessary for heavy OTR and ocean transport, barring some kind of quantum advance in the energy density storage capacity of fuel cells. (Although I suppose with reduced demand otherwise, biodiesel sources might be sufficient for transport needs.) And although we can synthize the necessary hydrocarbons for petroleum-based products through industrial processes it may always be far cheaper to extract them from natural petroleum.
I think it is, perhaps, a bit precipitous to categorically state that all problems with nuclear safety and waste disposal are solved; but most have solutions with an acceptible (if debatable) minimum of risk, and technological advances will continue to reduce those risks. The biggest problem with waste disposal is, in fact, with the low-level wastes which need to be incinerated or compacted to reduce bulk and allow for effective, safe handling. High-level waste (residual “exhausted” fuel) can be effectively neutralized by vitrification (encasing it in glass), although this makes it somewhat problematic to recover in future times if it is later desired to reprocess it. The biggest push needs to be to make these processes as automated, and indeed, automatic as feasable, while minimizing the possibility of some kind or runaway error.
The political and public perception issues are a different story, however. Despite the safety record of nuclear power (even Chernobyl is estimated to have resulted in less than 300 “premature” deaths due to radiation exposure, not counting the persons who died on site) the public perception is one of fear and hatred; and in some ways, this is not unjustified, given the enforced bureaucracy and sometimes bumbling, careless nature that have led to accidents and near accidents. This, combined with concerns about waste disposal and the all-too-reasonable concerns of nuclear proliferation creates a perceptual hurdle that no amount of technological safeguards can entirely remove.
Nonetheless, this may end up being our only viable choice for wide-scale electrical generation in coming decades, especially as developing nations like mainland China are demanding massively increased energy budgets. We have the choice to lead in developing and marketing mature fission plant designs and other alternatives, or letting developing nations license less-robust obsolescent designs from Russia and China.
Stranger
But the origional claim was not 5-7 “times”, it was 5-7 orders of magnitude… which is 100,000 to 10 million “times”. The latter seems pretty incredable.
I dunno if this is off-topic or even perhaps mentioned in one of the psuedo-science cites. Also, it will become obvious that I am NOT a scientist of any kind.
However, would it be possible to plop a solar collector on the sunny side of the moon [no clouds and always very bright] and attach it to the equivalent of a huge capacitor. Then, once a day or so, when things line up, have it transmit said stored energy back to earth to a facility awaiting to receive the transmission. Maybe transmitted by laser or something. Could add a satellite or two, as intermediate steps, to insure line of sight or focusing or whatever.
Ahh. I misread.
Yes, that seems to be an overstatement.
No.
Firstly there is no “sunny side” of the moon. There is a “dark side” of the moon but that’s dark as in unexplored/undiscovered. Not dark as in no light. The dark side always faces away from the Earth so we can’t see it. It is however in sunlight only half the time just like any point on the Earth. The day length just happens to be 30 days rather than 24 hours.
So although there are no clouds etc you won’t actually get more hours of daylight in a year than on Earth. And of ocurse because the day is 30 days long things would only line up every 10 days or so. That’s a huge capacitor.
Ok I’m at work right now and I don’t have time to dig up all my sources. I’ll dig 'em up when I get home, but the rough figures I used (i’m rounding from memory) were: 500,000 GJ per metric ton of uranium oxide. 50 GJ per metric ton of fossil fuel. Then I found a table showing Uranium tonnage vs. concentration (starting with almost pure oxide on the left of X axis and salt water concentrations on the very right). I eyeballed the chart, and eyeballed how much of the uranium that’s available in the crust actually reasonably accessible (seemed to be around 1/100th of the uranium on earth). I got a tonnage, which I multiplied by the 500,000 GJ figure. Then I found a site described coal and oil reserves, converted to tons, multiplied.
Compared energy yields. This isn’t precise science since I’m not a geologist or a physicist (physics minor), but comapring the energy yields produced the 5-7 orders of magnitude figure (the actual number in my calculation was 8 orders of magnitude, but I made so many assumptions and estimations).
Now, I was hurried in the first place, which means there’s is probably a stupid calculation mistake or a wrong assumption somewhere. I’ll try to redo everything tonight in a more scientific fashion. I apologize if I confused anybody.
Also, without any math, it seems uranium yields 4 orders of magnitude more energy per fixed mass than fussil fuels. Uranium is also as common as tin. Now, I’ll admit I’m not really sure how common tin is, but I wouldn’t be surprised if there was a few orders of magnitude more tin by mass than fossil fuels. However, I’d imagine that uranium, as well as tin, can be pretty damn deep in the crust, while fossil fuels should have a reasonable maximum depth. That might make fossil fuels much more accessible. Although, being a much better energy source, Uranium might be economical to mine much deeper than we will ever dig for coal/oil/gas. Maybe as deep as it is found in sufficient concentrations.
There isn’t? On what basis do you state that? “No doubt” is a pretty big call to be basing the entire energy future of our civilisation on.
We go really far out of our way to mine oil, gas and coal. Since uranium is 4 orders of magnitude more energy dense, (although it’s harder to extract this energy), it’s a good bet that Uranium is profitable up to at least 2 orders of magnitude more effort than fossil fuels.
At the moment, yes. But we were talking about the financial and energy costs of extracting it from seawater, which are entirely unknown but guaranteed to be higher than getting it out of the ground.