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Nuclear fission leaves out Depleted Uranium which reacts to hydrogen. These are used as shells for tanks and armors of tanks. It doesnt touch anything because its coated. The waste isnt really a waste, it can be used.


Fission is a effective type of reactor we have right now. It isn't as dangerous as you think, because I've only seen such meltdowns in poor countries where they use poor type of shieldings. And Fission doesn't use 'tons' of Uranium. They use 'tons' of Uranium to make Enriched Uranium.

It's not quite as nice as fusion, but at the moment it's almost as cheap for the power you get as fossil fuel plants, and it is actually much less dangerous than burning fossil fuels.

Essentially none, no, and what waste there is is very easy to deal with.

Exactly. I mean, the Hindenburg certainly produced lots of water!

Well, indirectly, yes. But in terms of what plants we build and how they work and what they do, we can consider them quite different for the time being.

Well, you're going to have dead yeast, probably some sugars and various other by-products of fermentation in the mixture. Not to mention that yeast dies once the ethanol reaches a certain concentration, so you're going to be left with mainly water.

The method I would use to get the pure ethanol out of that mess would be to first centrifuge the product to get rid of the solid stuff, then pour the resultant liquid off and perform some kind of distillation on it to purify the ethanol. You need power for both of these steps, and to me it all seems horribly inefficient.

You still wouldn't be able to get pure ethanol this way though - I think the boiling points of it and water are too close. See the information in this abstract to see the outline of an actual method for extracting ethanol from fermentation products.

You know depleted uranium comes from enrichment, but way more radioactive substances come from nuclear fission like radon, polonium and they take forever to decay.
Fission is not the way to go. (not that fossil fuels are either)
Oh I beg to differ. Radioactive waste is totally dangerous. Read the above statement.

Interesting, I expected that there would be an easier way to get ethanol refined.

alcohol boils at 78 degrees celcius. water boils at 100. I dont call that close.
http://en.wikipedia.org/wiki/Ethanol
personally, you can divide water and alcohol by yourself. but it would require alot of labor to make them.


What are you pointing out?

I'm pointing out that millions of drums of radioactive material are being dumped underground and god knows where else. They release harmful radiation with more acute effects than CO2 emissions. What do you think people are going to do with all this material? Just keep burying it where ever we can?
Besides, as we all know, some people can become corrupt in positions of power, who's keeping the head of radioactive material from selling polonium to terrorists or threatening countries? That IS one of the risks of continuing nuclear fission believe it or not.
Meltdowns at this point aren't very threatening, better knowledge and better safety regulations keep it from happening. (though still possible)

It's dangerous if you're near it. But unlike coal and oil smoke, which hangs throughout our atmosphere and which everybody has to breathe, waste from fission plants can easily be contained and put where it won't harm anybody.

Also, one thing I can't stand is how people seem to think that nuclear fission creates radioactivity. It doesn't. As far as I know, it actually lowers the total amount of radioactivity. In other words, the only reason that waste from fission plants is dangerous is because it's concentrated; if you took all the world's uranium, ran it through power plants, and then spread it all out again in the same proportions, the environment would actually be safer than it was before.

This is another common myth. If I remember correctly, only specially designed breeder plants make the right materials for nukes, and most fission power plants actually produce very little material useful for weapons.

I would call it too close. Consider that liquids don't heat evenly and you have a problem - parts of the solution will be hotter than others, and water and ethanol will boil off at the same time. The article I cited says that using distillation you can only get 90-91% ww. ethanol by distillation. Somewhat ironically, you also need gasoline to separate out the ethanol from the water in the final step of the process, although I believe it says that this can be re-used.

GreenMeklar, how does a breeder reactor work again? Its more efficient if I remember correctly. It reuses U-235 or something right?

Alcohol heats much faster. Good hypothesis, I didn't think of that.

the temperature at which either of those liquids will boil also depends on the pressure that they're under. At a higher altitude things boil at a much lower temperature, so you can always change your boiling point if u want, just put the stuff in a -i know this is crudely put- pressure cooker, but it will give u a much quicker boil for either liquid, perportionally of course

Roflocaust. Electricity is absolutely the EASIEST form of energy to distribute. Have you heard of grids? They cover all populated areas of the united states. Can you say as much for gas stations that sell ethanol, let alone plants to distribute distilled hydrogen in fuel cells.

As for the distillation of ethanol, is it as difficult as the distillation of pure water, which could then be distilled into H2, and the compression of the H2 into supercooled containers (which noone has adequately invented yet)? Fuel cells haven't even been invented which can stand a bumpy car ride let alone a crash.

When you consider the inefficency of ethanol consider that the gasoline it replaces is inefficently transported six-thousand miles to get to your gas tank.

Nuclear fusion, unfortunately cannot be considered in this argument as a valid alternative because so far it only works at forty-million degrees, however if it was part of this argument, it would annhilate all competition because the ridiculously abundant fuel sources including the entire ocean, and the entire surface of the moon, along with the huge amounts of clean energy produced would be absolutely beyond competition from other alternatives. Unfortunately nuclear fusion may be much more than a long way off.

I pale when I hear environmentalists bemoan nuclear fission, however. The wastes of fission are so miniscule and concentrated that they can actually be dropped off at the bottoms of existing mine shafts and eventually destroyed by the heat and pressure inside the earth. The energy produced is perfectly clean, and as for safety, does anyone care to guess how many reactors are operating, have been operating for decades with no problems?


Another Big argument with hydrogen.

As of 2004, 50% of the electricity produced in the United States comes from coal, 20% comes from nuclear, 18% from natural gas, 7% from hydroelectricity, 3% from petroleum and the remaining 3% mostly coming from geothermal, solar and biomass. http://www.eia.doe.gov/cneaf/electricity/epa/figes2.html

But oh yeah! we have all those dams.

actually it wouldn't be proportionally. PV=nRT I don't feel like giving an example. I cant even remember avogadros number 6 something to the 20 something.

I dont think radioactive material goes away the way you mention it.
I also dont think I want the center of my planet to be radioactive.

The problem is you're thinking about it. Just look it up:

"Whether reprocessed or not, the volume of high-level waste is modest, - about 3 cubic metres per year of vitrified waste or 25-30 tonnes of spent fuel for a typical large nuclear reactor. The relatively small amount involved allows it to be effectively and economically isolated."

http://www.uic.com.au/wast.htm

Certain wastes can be reused in other reactors, most wastes are scarcely radioactive, and others can be transmuted.

That seems reasonable enough - just seal it in concrete blocks and store it underground.

Have you considered dumping it in a subduction zone (where the Earth's crust slides under another plate)?

we could always put it on the moon

Captain Will, that's what I was referring to in my first post, the subduction one. Thanks for bringing that up, because i couldn't find information on it quickly enough to source it.

ooh, I hope this topic stays open for a few more days, I have someone I'd like to talk to about nuclear fission.

As far as I know, breeder reactors are the fast reactors, which use highly radioactive fuel and are designed to produce more highly radioactive fuel of other types. As far as I know most reactors used for power generation are slow reactors, but I'm not sure.

It's easy to distribute...but it's quite hard to store. That's the problem.

Exactly. When you actually look at how safe an clean fission is compared to fossil fuels, there's no contest.

If you really, really need to get rid of it, for a long time, then yeah, dumping it into a subduction zone would do that pretty effectively. Unfortunately it would take a while for the stuff to get down to where it could melt and sink into the mantle. Personally I think the idea of dumping it into mine shafts and spent oil wells is probably more environmentally friendly.

Do you have the remotest idea how much that would cost? Way. Too. Much. It costs something like $5000 to put one kilogram of whatever into orbit, and somewhat more than that to put it on the Moon. Even if we built space elevators and brought the cost down to $100 per kilogram or so, it still wouldn't be economical. Sorry, but this is one very bad idea.

Well, I would seal it in concrete before dumping it in the subduction zone so it wouldn't matter too much how long it took to sink.

Uh, space elevators wont cost 100$ per kilogram. It would cost around 15,000$ a lift off. It would be just effective to lift around a lot of material. And yes, putting radioactive waste is a bad idea on the moon. since your problem isn't really the problem, but too much on it might distabilize the orbit on earth.

Oh, with breeder reactors they reuse some U-235 and Polonium I think. Too bad most US reactors aren't breeder reactors (another reason why nuclear isn't a great alternative)

I do understand that Nuclear is better than Fossil fuels, but if you're gonna look for an alternative you might as well go farther and use even more efficient fuels. (Hydrogen battery, solar, wind, hydro and even fusion if it turns out well).

Of course. Otherwise it's hard to keep it from getting spread around by ocean currents.

Which equates to how much per kilogram? In other words, how much payload mass do you expect to carry on each lift? Anyway, $100 is just a rough estimate based partly on this Wikipedia article. The actual cost could be anywhere within about a factor of 5 in either direction.

WHAT?

Do you have any idea how much nuclear waste it would take to make much of a difference to the orbital system of the Earth and the Moon? Okay, let's say that a 0.1% change in the mass of the Moon is enough to cause a problem. It would probably take somewhat more than that, but I'm erring on the side of you being right in order to prove just how wrong you are.

The moon has a mass of 73600000000000000000000 kilograms. 0.1% of that is 73600000000000000000 kilograms. As of 2001, humans consumed about 1700000000000 watts of electricity; we'll estimate that by the time we have space elevators this will be up to 3000000000000 watts. It requires about 0.0000000036 kilograms of standard nuclear fuel to produce one watt-hour of electricity. This means that, every year, our future civilization will produce about 94672800 kilograms of nuclear waste (this is assuming the amount of mass lost during the reaction is negligible). At this rate, it would take us no less than 777414421000 years, or 56.7 times the age of the Universe, to make a significant change in the Moon's orbit.

You may consider yourself owned.

The problem is, so far we don't have a more efficient energy source that is also both reliable (solar and wind rely on the weather) and easy to get lots of (geothermal is only useful in certain places).

Wind generators cause birds to die. Somehow, they fly into those fans then get hit by it.


Iam owned. But its still a possibility whether or not impossible. Our moon isn't so strong enough to have its own atmosphere. And dont imagine this much. 3000000000000 watts. Imagine 3,000,000,000,000 mW.

Green meklar... Where did you get those numbers? Each reator produces tons of waste a year.
Either way, its inefficient and there are better alternatives.

Going in my quotes collection.

What does that have to do with it? The Earth's atmosphere accounts for only 0.000086% of its mass.

That is a very large number. In fact, it is about four times as much power as the Earth receives from the Sun. In other words, to generate that much power you would have to have a circular solar panel in space with twice the radius of the Earth. Personally I don't see how our power use could possibly increase by a factor of 2000000 between now and when we get space elevators.

I looked it up on the Internet. I forget which sites exactly I looked at, but I think they were all genuine. Besides, my measurement is still over 94000 tonnes per year total, so I think that fits your statistics well enough.

WHAT? It's a few thousand times as efficient as coal and you call it inefficient? Get real.

Well, where they can be used I'm all for solar and geothermal power. But where they can't be used it seems that fission power is the best kind of power available with current technology.