News Global Warming and the stupidity of (wo)man

  • Thread starter lubuntu
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lubuntu said:
My point is our goal shouldn't be to use less energy because that isn't really a solution to the problem, the solution is to harvest that silly thing 93 million miles away that is spewing out a kw per sq ft!
More like 30 watts per sq ft. That's total, not what we can actual use with current technology. Solar power research is great, but if we want to use it on a very large scale, we'd better have the collectors in space where they wouldn't significantly block sunlight from reaching earth's surface.
Quite right. Perpendicular to the radius vector of the sun, the average irradiance is 1321 - 1413 W/m^2. The image of the earth (projected onto the plane normal to the sun) has area [itex]\pi R^2[/itex] (the circle facing the sun), while its surface area (a sphere) is [itex]4 \pi R^2[/itex], a factor of 4 difference - this averages over both latitude variations., and the diurnal cycle. This is ~340 W/m^2 (32 W/ft^2), and then a further reduction (don't know the value) for losses from absorption by the atmosphere. And then large losses in conversion inefficiency (either photovoltaic or thermodynamic (Carnot losses)).

There's some subtle points involved. For instance, since a solar panel/receiver can be oriented at angles to the earth's surface, to be parallel to the normal plane. So the latitude variation is meaningful for land use, but not meaningful for collector area needed (which is the cost-determining factor). Different adjustments are needed.
Al68 said:
The practical solution is nuclear power. Current technology is vastly cleaner and safer than the existing power plants that were designed in our (nuclear) infancy. Even the existing plants are far and away cleaner and safer than other sources. And we won't have to worry about running out of fuel for a VERY, VERY long time.
Totally agree. :smile:
 

SixNein

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Again, a MUCH smaller problem with current technology. Existing plants use the technology that existed shortly after we first split the atom.

Even with current radioactive waste, the actual health problem pales in comparison with other power plants. The health standards for radioactive waste is much more stringent than other hazards, in comparison to the actual health risk. Public perception doesn't match reality. It's amazing that the same person who is scared of a truck with radioactive placards will think nothing of a fuel tanker, which is a much greater health risk, even aside from the immediate potential danger.

Even the people who work directly with radioactive waste are exposed to radiations levels that are very small compared to what is routinely used in hospitals for simple tests. And that's the way it should be, since in hospitals, the small risk is outweighed by the benefits. And the levels the radioactive waste workers are exposed to are even small compared to what the average American is exposed to by natural sources, ie radon, etc. Bottom line is, there's a lot more hype than substance.
The health risks to mankind from nuclear waste are astronomical. You have to store nuclear waste for hundreds of thousands of years. Take a look at how much waste would be generated to power the current world consumption, and add 3% each year for increased demand.

Nuclear power is not the solution.
 
Nuclear power is not a solution. We would produce LAKES of radioactive waste if we powered the world in this fashion.
SixNein said:
The health risks to mankind from nuclear waste are astronomical. You have to store nuclear waste for hundreds of thousands of years. Take a look at how much waste would be generated to power the current world consumption, and add 3% each year for increased demand.
One, you're drastically exaggerating the volume, and two, the lifespan of spent fuel can be greatly shortened with fast reactors.

Here's what the current numbers are:

http://en.wikipedia.org/wiki/Burnup

Take the modern figure of 60 GWd(thermal)/metric ton fuel, and invert it. At (say) 33% thermodynamic efficiency, that's 1 metric ton / 20 GWd(electric), or less than 20 tons / GWe-year (that is, one reactor running for one year). This is about a cubic meter.

And still without considering fast reactors, look what simple chemistry does:
Fresh uranium oxide fuel contains up to 5% U-235. When the fuel reaches the end of its useful life, it is removed from the reactor. At this point it typically contains about 95% U-238, 3% fission products (the residues of the fission reactions) and transuranic isotopes, 1% plutonium and 1% U-235.
http://www.world-nuclear.org/info/inf60.html

95% of spent fuel is depleted uranium, of very low radioactivity. So chemical separation (reprocessing) can reduce the volume of actual high-level waste by a factor of twenty - 1 MT/GWe-year, or 0.05-0.1 m^3 (not sure about densities). Size of... well, a breadbox.

And when you burn the transuranic isotopes (plutonium, neptunium...) in fast breeders, what is left decays extremely fast (well, comparatively), reaching natural ore levels on the order of a century ([itex]10^2[/itex] years, not [itex]10^4[/itex] years). If you look at the fission products (the other component of spent fuel), their half lives are bimodal: you have short-lived ones with [itex]\lambda < \mbox{30 years}[/itex], and long-lived ones with [itex]\lambda >\mbox{ 200,000 years}[/itex], the latter being much less radioactive. But nothing in between - the difficult part of spent fuel, the minor actinides, are destroyed in fast reactors.

http://en.wikipedia.org/wiki/Fission_product#Characteristics

http://en.wikipedia.org/wiki/Minor_actinide
 
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A

Al68

The health risks to mankind from nuclear waste are astronomical. You have to store nuclear waste for hundreds of thousands of years. Take a look at how much waste would be generated to power the current world consumption, and add 3% each year for increased demand.

Nuclear power is not the solution.
That's a huge exaggeration. A little research into the facts instead of the propaganda will show that.

Truth is that the average human is exposed to ~200 mrem/yr from radon alone, about 360 mrem/yr average from all natural sources. A single medical xray averages about 50 mrem, dental xray about 18 mrem. Average exposure from nuclear weapons testing is about 0.5 mrem/yr. From nuclear power plant waste, <0.5 mrem/yr. And that's from 50 year old technology plants.

Saying the health risks are significant is an exaggeration, astronomical is just too absurd to even think about. Wild, ridiculous, and absurd claims won't solve the problem.

And the amount of radioactive waste that would need to be buried is likewise small in comparison to the naturally occurring radioactive material already in the ground with no safeguards whatsoever. Anyone who thinks that buried radioactive waste from power plants even compares to the radon seeping up out of the ground into peoples' houses are seriously misinformed.

The only significant risk is to the workers who actually handle the waste, and even that is very small compared to common everyday risks in life. As an example, a lot of medical tests cause radiation workers to be banned from entering radioactive waste sites because they will set off radiation alarms just from the residual radioactive material left in their bodies.
 
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And again, can't we postulate that with time and technology we can only get better at using nuclear energy?
 

SixNein

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That's a huge exaggeration. A little research into the facts instead of the propaganda will show that.

Truth is that the average human is exposed to ~200 mrem/yr from radon alone, about 360 mrem/yr average from all natural sources. A single medical xray averages about 50 mrem, dental xray about 18 mrem. Average exposure from nuclear weapons testing is about 0.5 mrem/yr. From nuclear power plant waste, <0.5 mrem/yr. And that's from 50 year old technology plants.

Saying the health risks are significant is an exaggeration, astronomical is just too absurd to even think about. Wild, ridiculous, and absurd claims won't solve the problem.

And the amount of radioactive waste that would need to be buried is likewise small in comparison to the naturally occurring radioactive material already in the ground with no safeguards whatsoever. Anyone who thinks that buried radioactive waste from power plants even compares to the radon seeping up out of the ground into peoples' houses are seriously misinformed.

The only significant risk is to the workers who actually handle the waste, and even that is very small compared to common everyday risks in life. As an example, a lot of medical tests cause radiation workers to be banned from entering radioactive waste sites because they will set off radiation alarms just from the residual radioactive material left in their bodies.
Why are you trying to downplay the risk of nuclear waste? Your trying to compare high end radioactive waste to a microwave. We are talking about nuclear production on a higher scale, with higher waste output. You have to store this output for thousands of years. If it was to get into the water supply, people would have a large problem.

Lets say that they made advances to completely reprocess the entire fuel. Nuclear power would still not be a viable solution to global warming. You would have to allow every single country to have nukes.... it's unthinkable.
 

Borek

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May I suggest that we remove "Global Warming" part of the subject?
 

neu

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I'm really annoyed that everyone seems to only react to my statement that global warming hasn't been conclusively shown to be caused by humanity. Thats not the point, whether it is or it is not.
You shouldn't have said it then.
 
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It appears that both "global warming" and nuclear power could be number one and two on the list of suitable moral panic subjects. As long as moral panic is a central part of our society, there is little chance for objective trouble shooting.
 

mheslep

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...For instance in 1988 Hansen predicted a temperature rise of about one degree celsius by now.

Hansen06_fig2.jpg


and http://www.cru.uea.ac.uk/cru/data/temperature/hadcrut3gl.txt [Broken]

See the averages of the last few years:
2006 - 0.422
2007 - 0.405
2008 - 0.324

And 0.370 for January 2009.
Note that scenario A is predicted by Hansen's model given his preconditions:
A: "the assumed annual growth averages about 1.5% of current emissions, so the net greenhouse forcing increases exponentially". Emissions have increased by that and more, so A is his predicted model.
 
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Evo

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This forum is only for discussion of the politics and current news about issues, not for scientific discussion. Thread locked.
 

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