Question 1: Energy

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AuthorTopic: Question 1: Energy
...b10010b...
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Mind turning that into a link? It's stretching the page, and everyone's seen it anyway.

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Posts: 9973 | Registered: Saturday, March 30 2002 08:00
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I'm a supporter of nuclear power as well. You'd think there'd be some way, with the new CEV or something, to send a bunch of nuclear waste into the sun.

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-ben4808
Posts: 3360 | Registered: Friday, June 25 2004 07:00
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quote:
Originally written by Thuryl:

quote:
Originally written by Leena:

If it would take every car 8 hours to re-charge the batteries, then it would be impossible for every car to get charged overnight, which is when more people would be able to get their batteries charged. Unless you are talking about the car owners owning battery chargers as well, but wouldn't that cost a great deal of money? On top of the $40,000 you are paying for the car. It sounds awesome in theory, but knowing humans it’s highly unlikely to ever happen.
I would think that on top of the $40,000 you are paying for the car, a battery charger wouldn't be all that much extra. :P

Actually, that entire problem could be solved with a tiny bit of organisation. What if all service stations had supplies of around 20 full batteries and a charger? When the car owner gets to the service station with an empty battery, they take out the battery, measure how much charge is left, get paid an appropriate amount for recharging it, give the car owner a new full battery, and start the empty one charging. The car owner drives off with a full battery without having to wait for the old one to finish charging.

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LINKAGE
Posts: 364 | Registered: Saturday, January 17 2004 08:00
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Ben: I believe that has been proposed, but there are a few little problems.
1) The cost. Sending things into orbit is hard enough. Escaping the Earth's gravity entirely is even more fuel intensive. To send all of our nuclear waste into the sun would, at this time and at any time in the near future, be prohibitively expensive.
2) Safety. What if we had an explosion at launch, think of the damage that would be done. *i would know more than I do about how securely contained nuclear waste is, but launch pad explosions are incredibly powerful. The more safety features you put to secure the waste from leakage in the event of the disaster, the larger payload you will have to send up.

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"As our circle of knowledge expands, so does the circumference of darkness surrounding it." --Albert Einstein
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Posts: 536 | Registered: Sunday, September 7 2003 07:00
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quote:
You'd think there'd be some way, with the new CEV or something, to send a bunch of nuclear waste into the sun.
We could, but there is no reason why we should. One is that I would have safety concerns. Granted, we've launched nuclear material into space before (primarily Pu238), fission products tend to be a different story.

The other issue is that it would be a waste of a valuable resource. Spent fuel retains about 97% of its energy content. Although not economical to recover now -- uranium is so cheap -- it is a potent energy source for future generations that would be a pity to waste.

The truth about Yucca Mountain is that the spent fuel is not going to be in there for 10,000+ years. It's too valuable to not be mined. We will still need a repository to store the fission products, but those are only a threat for a few 100 years, something we can manage. The long lived plutonium and actinides are rich in energy.

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Posts: 3726 | Registered: Tuesday, September 18 2001 07:00
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quote:
Originally written by Leena:

Unless you are talking about the car owners owning battery chargers as well, but wouldn't that cost a great deal of money?
Every electric car sold today (and there are a number — I've ridden in one, albeit one owned by the late Jef Raskin) comes with a charger. I see no reason why that would change, since, as Thuryl said, the chargers aren't terribly expensive in comparison with the car.

quote:
Originally written by Strontium:

With respect to electric cars/plug ins leading to higher fuel efficiency:

where does the electricity come from? Solar? Nuclear? Hydro?

It comes from whatever powers your house, which is usually a damned lot more efficient and less polluting than an individual engine. Making energy at a power plant is more efficient than making energy in your car.

quote:
Originally written by PoD person:

almost every basic necessity requires a car trip: groceries, school, other child-care, and home-improvement supplies are all a 5-10 minute drive (i.e. a 30-60 minute walk) from my house.
This is one of the few things that gives me hope for electric cars yet. Consider the electric minivan: a soccer mom has absolutely no need for a car that drives more than 100 miles in one shot, and her car is likely the second or third car that the family owns, so for more extensive driving, the other cars can be used. I can see marketing such a thing to rich people.

Drew's probably onto the right track, though: plug-in hybrids exist now that get absurd gas mileage. Between plug-in hybrids for private cars, biodiesel for big trucks and shipping, and (eventually) hydrogen for everything bigger, we may be able to significantly reduce the amount of petroleum used in transportation.

Of course, this will require the market hemorrhaging gas prices more than it already has, but I think that's a given.

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I may have an idea...air pressure. Have a piston in a valve be pushed upwards, as like in a car motor, and as it goes out, it pulls on a diaphram which draws out enough pressure that when the piston reaches a certain point it is then forced back into the valve and so on and so forth.

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When you think you can't get any lower in life and hit rock bottom, God hands you a shovel.

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Posts: 615 | Registered: Friday, May 3 2002 07:00
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quote:
Originally written by Cairo Jim:

I may have an idea...air pressure. Have a piston in a valve be pushed upwards, as like in a car motor, and as it goes out, it pulls on a diaphram which draws out enough pressure that when the piston reaches a certain point it is then forced back into the valve and so on and so forth.
Have you taken physics?
Posts: 2242 | Registered: Saturday, April 10 2004 07:00
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quote:
--------------------------------------------------------------------------------
Originally written by Strontium:
With respect to electric cars/plug ins leading to higher fuel efficiency:

where does the electricity come from? Solar? Nuclear? Hydro?
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quote:
quote: kelandon

It comes from whatever powers your house, which is usually a damned lot more efficient and less polluting than an individual engine. Making energy at a power plant is more efficient than making energy in your car.

Whatever powers your house is primarily a fossil fuel. So, electric cars don't replace fossil fuels they are a derivative of them. Hence the problem. Plus, we have to expend massive amounts of energy to replace the fleet of vehicles.

quote:
quote: Thuryl

On another note, what about other industries that rely on petrochemicals? The plastics industry uses huge amounts of oil; bioplastics aren't currently very good, and they run into the same problems in terms of resources required to make them as biofuels.

Virtually all of our food is grown with petrochemicals - fertilizers, pesticides, other (necessary) chemicals

And *i, with respect to the resources/reserves debate I got your original point. I think reserves is the more valuable term as its not just a question of economics its also a question of technology. Reserves are exploitable because we can access them/extract them.

I would even be interested in a debate on what is the real restrictor on nuclear technology and it may be the cost of capital and time - to erect new plants to replace fossil fuels. I would also factor into the capital cost the amount of fossil fuels used to get such a system up and running.

The problem with alternatives to fossil fuels is that they either aren't technologically feasible on a massive scale or the timelimes to bring them on stream push their implementation beyond the exhaustion of fossil fuels.

Alex, I was exagerating (too grandiose), the estimated area is about 300 miles on a side - see the book by David Goldstein, Crude Awakening.

See also this link, the point of which is the impracticality of looking to solar/wind power to replace that which we consume from fossil (currently 0.2% of US power is so derived):
http://www.eia.doe.gov/cneaf/solar.renewables/page/trends/table1.html

[ Thursday, April 27, 2006 05:03: Message edited by: Strontium ]

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Posts: 687 | Registered: Wednesday, January 19 2005 08:00
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quote:
Originally written by Strontium:

Whatever powers your house is primarily a fossil fuel. So, electric cars don't replace fossil fuels they are a derivative of them. Hence the problem.
Re-read my reply. Fossil fuels are vastly more efficiently processed at a power plant than in your car. It's still a big improvement.

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Arancaytar: Every time you ask people to compare TM and Kel, you endanger the poor, fluffy kittens.
Smoo: Get ready to face the walls!
Ephesos: In conclusion, yarr.

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Posts: 7968 | Registered: Saturday, February 28 2004 08:00
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quote:
And *i, with respect to the resources/reserves debate I got your original point. I think reserves is the more valuable term as its not just a question of economics its also a question of technology. Reserves are exploitable because we can access them/extract them.
No you didn't.

Economics is the primary factor in the case of uranium as it is for many materials. We have the technology to extract lower grade ores, we just don't because it does not make sense to do so today.

The point is that the reserve is artificially low because of many factors. We have lots of high grade ore in Canada. Because of this, other veins of uranium that we used to mine are no longer part of the reserve because there is no economic reason to go there.

Compound this with warhead decomissioning which offers essentially a "free" supply of abundant nuclear fuel. This especially makes mining of lower grade ores (again, we used to mine them just fine) even less attractive to mine.

I'll use a simple analogy of clamshells. Let's suppose that clamshells are a valuable resource and there are 500 million clamshells in the ocean and we use 1 million clamshells per year meaning a 500 year supply of the resource. Getting clamshells from the ocean is a fairly expensive task. We could under current economics recover 100 million of them. This sets our reserve at 100 years.

Now suppose a tsunami occurs that washes up 30 million clamshells onto the shore. Suddenly, we have a free 30 year supply of clamshells that we did not have access to before. There is no economic reason to go to the oceans anymore, so our reserves have decreased to 30 years even though we have not suddenly consumed 70 million clamshells.

25 years later, going to the ocean suddenly looks more attractive as the free supply is running out. Suddenly, the reserves increase from 5 years to much higher because the supply in the oceans is now economic.

This oversimplified example is pretty much true for uranium. As current reserves run dry, we explore to expand the reserves. As exploration efforts have been minimal to date, geologists believe this can be expanded quite readily. At the same time, lower grade ores become attractive again (the slight penalty in cost is still competitive) so the reserve would increase from 50 years to let's say 200 years.

Lower and lower grade ores (which are exponentially bigger) will continue to be extracted until we run into economic or technological limits. It's going to be the former that stops us, not the latter.

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You missed my point. Reserves ARE important because they detail what is presently available to develop.

In the short term there are significant predictions of shortages (2005 rport by the Asia Pacific Foundation of Canada said that there was likely to be a 45,000-tonne shortage of uranium in the next decade)

In 2001 the European Commission also predicted shortages and stated that no new sources were immediately available as mines take approximately 10 years to develop. This is not clamshells, uranium does not "suddenly" wash up on shore (SCi-fi perhaps?), it must be found, extracted and processed. the EC estimate of natural supply was 42 years, extended to 72 if military sources were included (based on 2001 rates of consumption). Note that decommissioning as a source extends supply only 30 years and IS finite.

I am well aware that long term predictions of base metals shortages consistently prove false as mineral sources are (relatively) inexhaustable from a geologists point of view (coal and oil being exceptions). It is short term supply availability that is an issue. Nuclear Engineering International (2004) predicted short term supply shortages beyond 2010.

Although, not to be all doom and gloom, it is possible that use of decommisioning sources MAY bridge the supply gap until new sources are developed, if work on developing those new sources happens fairly quickly.

[ Thursday, April 27, 2006 08:03: Message edited by: Strontium ]

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"Dikiyoba ... is demon ... drives people mad and ... do all sorts of strange things."

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I agree. The reason for the shortage in the short term is because there is a sharp increase in demand that outpaces supply. In other words, we cannot bring enough mines online fast enough to fill the demand increases.

This is a short term issue, and I agree it is important, but as far as the long term availability, there is no issue. Eventually the mining capability catches up, and things will be fine.

You had, however, put up an argument that there is only about a half-century left of uranium that we can extract. This is totally incorrect. There is plenty and as demand increases, the supply can continue to increase almost indefinitely. It's just that sharp increases in demand can cause temporary shortages.

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My original argument was based on the EC report of 2001 - detailing a life of 42 years for known reserves - which I didn't correct/allow for discovery of new reserves but also which doesn't take into account replacing fossil fuels with nuclear.

Interesting, in a quick search of the internet came across this article

http://www.fraw.org.uk/mobbsey/papers/oies_article.html

and quoting from it "Even so, taking these two factors together alongside a six-fold increase in capacity, the lifetime of the known and estimated uranium resource would still be less than 50 years." The two factors were a four to eight fold exppansion of the industry and and the use of more efficient nuclear technology.

He also cites a 1975 book that debunks use of sea water - as the energy used for extraction makes this a net negative energy source.

He also quotes from an article estimating supply to be several thousand years, and then discredits it.

So, it seems there may be credible science behind limited supply for uranium as well - although this is fundamentally a different material than fossil fuels (limited one time event vs. consistent presence in geology). Care to comment?

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As a general rule, it's a bad idea to argue with a nuclear engineer over uranium supply. This stuff is his livelihood.

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"As our circle of knowledge expands, so does the circumference of darkness surrounding it." --Albert Einstein
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Your source drastically underestimates the amount that fast reactor technologies could extract. Currently about 2-3% of the energy available is used. A closed fuel cycle would, from estimates I have seen, increase it by several factors of 10.

Of course, we must expend additional energy resources to reprocess, but the amount is not all that much comparatively. You will come out ahead if you do that otherwise there would be no point.

As for ore grades, energy for extraction depends on the technology. New methods are being developed all the time for extracting and enriching uranium more efficiently. The 1975 cutoff likely assumed once-through fuel cycles, gaseous diffusion methods of enrichment, crude fabrication, and speculative disposal costs. I'd be curious to see this analysis done with today's technologies.

The far more efficient centrifuges alone changes the net energy picture drastically. Better efficiency in even mundane processes can increase the lower grade of ore.

The other big thing that is not addressed is the thorium breeding technology. Thorium is even more abundant than uranium and can be converted to a nuclear fuel under thermal neutron conditions. If all else fails, we have this resource.

The study also assumes we replace a large fraction of the fossil fuels with today's nuclear fission technology. No one has suggested we do that, in fact we shouldn't for a variety of reasons. Nonetheless, fission is likely secure for the next few centuries even with wide growth.

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quote:
Originally written by Strontium:

Reserves ARE important because they detail what is presently available to develop.
I think Stareye made his semantics point precisely because this statement is false. Your figures list what is presently cheap to use, not what is presently possible to use.

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Arancaytar: Every time you ask people to compare TM and Kel, you endanger the poor, fluffy kittens.
Smoo: Get ready to face the walls!
Ephesos: In conclusion, yarr.

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Well, he has a valid argument about the energy utilization once he drew the distinction from cost versus energy benefit. However, I do think he still only factors in the "proven" reserves which are things we have directly measured.

For instance, Tantalum had about a ten year reserve according to a 1990 graph I saw. We have not run out of Tantalum and the price has not increased due of scarcity. The point is we found more. There's plenty of Tantalum, it's just that we have to continually find it because we care to look. I suspect uranium will be similar.

As for the energy required to process, that's a legitimate concern. However, from what I can tell we are far from reaching that limit in the foreseeable future (> 100 years) even with an agressive expansion program. Of course we will need to adopt breeder reactor technology eventually if we wish to continue with fission, but that will significantly allow us to recycle the uranium already processed.

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Posts: 3726 | Registered: Tuesday, September 18 2001 07:00
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quote:
in order to extract useful work, you need a sizable temperature difference.
What about the huge difference between the hot sun and ambient temperature (water) on our earth?

[ Thursday, April 27, 2006 22:29: Message edited by: Yet another procrastinator ]

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...b10010b...
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Suuuure. Get back to me when you've built a heat engine that extends all the way from here to the sun.

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Whoever asked me before, I have done a little bit of physics, and as far as I no It is possible. I'm thinking of having it driven by the same sort of air pressure system our lungs use, using a diaphram of some sort to control the pressure so that it flows in and out of the lungs.

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When you think you can't get any lower in life and hit rock bottom, God hands you a shovel.

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...b10010b...
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quote:
Originally written by Cairo Jim:

Whoever asked me before, I have done a little bit of physics, and as far as I no It is possible. I'm thinking of having it driven by the same sort of air pressure system our lungs use, using a diaphram of some sort to control the pressure so that it flows in and out of the lungs.
You do realise that inflating your lungs uses energy from your muscles? Air doesn't just magically compress itself; you need to power an air compressor somehow. Where do you want the power to come from?

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From his earlier post, Cairo Jim was describing a classic perpetual motion machine. Unfortunately, they are forbidden by the second law of thermodynamics. Energy can't come out of nowhere. The reason your particular design doesn't work is that in an ideal circumstance, the machine could continue moving up and down forever. It doesn't create any net energy, the force required to create the energy will slow down and eventually stop the system. Even if you weren't trying to generate any power, the system would still eventually stop, due to frictional forces.

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Posts: 536 | Registered: Sunday, September 7 2003 07:00
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The diaphram is the muscle that draws air into your money via air pressure. The idea I came up with is not involving perpetual motion but using a diaphram sort of object that is 'flexed' when one of the rods in the piston is pushing against it to a point where the air pressure forces it the other way.

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In that case, what is going to keep sending the pistons back up?

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