Naked Science Forum
Non Life Sciences => Technology => Topic started by: cheryl j on 30/11/2016 01:26:47
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My brother and were recently arguing about politics and global warming (he's a skeptic; I'm not) and he claimed that fusion is what we should really pursuing. To be honest, I don't know much about it. Is it or is it not a potential alternative source of energy?
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Well, controlled fusion power has been 20 years away since the 1960s, and I'm not sure that we have made much progress since then. The difficulty is that it requires so much power to get started, and then releases so much power that it is difficult to maintain containment. As far as I know we have just barely succeeded in reaching "break even" (energy produced ≥ energy input), but nothing close to a useful reactor.
I would point out, however, that we do have access to a magnificent fusion reactor that is capable of providing many orders of magnitude more power than our entire civilization requires, and at a steady rate too! It's likely to last orders of magnitude longer than our civilization, and it is far enough away that we are protected from the neutrons it produces. I am talking, of course, of the Sun! My guess is that solar energy is the only viable and scalable method of harnessing fusion power in the next 50 years.
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okay. So I gather the sun can do it but we can't.
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So I gather the sun can do it but we can't.
The critical word here is "controlled".
Since the late 1940s we have been able to do "uncontrolled" hydrogen fusion, in the form of the hydrogen bomb. But nobody wants one of them in their back yard!
There are a number of projects trying different approaches to fusion, including:
- Overview: https://en.wikipedia.org/wiki/Fusion_power#Approaches
- Laser confinement, operating in the US: https://en.wikipedia.org/wiki/National_Ignition_Facility
- ITER, being built in Europe: https://en.wikipedia.org/wiki/ITER
Both the latter are massively expensive research projects, and neither will produce any electricity. But physicists are gradually overcoming more obstacles. The question is how many more obstacles will they face before they have an economical implementation?
In the meantime, solar cell deployment is racing ahead, worldwide.
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Cheryl j
The main problem is the large size required to get enough gravity for containment about 10^30Kg also the power output 10^23KW is very low relative the size and a lot of unwanted radiation comes off.
It is best to use the one we have despite it being 150,000,000 Km away.
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Well, controlled fusion power has been 20 years away since the 1960s, and I'm not sure that we have made much progress since then. The difficulty is that it requires so much power to get started, and then releases so much power that it is difficult to maintain containment. As far as I know we have just barely succeeded in reaching "break even" (energy produced ≥ energy input), but nothing close to a useful reactor.
I would point out, however, that we do have access to a magnificent fusion reactor that is capable of providing many orders of magnitude more power than our entire civilization requires, and at a steady rate too! It's likely to last orders of magnitude longer than our civilization, and it is far enough away that we are protected from the neutrons it produces. I am talking, of course, of the Sun! My guess is that solar energy is the only viable and scalable method of harnessing fusion power in the next 50 years.
Chiral is absolutely right. Here we are on Earth, moaning about a lack of energy! When every day a gigantic thermonuclear reactor, in the form of the Sun, rises in the dawn sky. Safe and Neutron-free, thanks to distance and our Earth's atmospheric shield.
The Sun can supply all the energy we will ever need for billions of years. We only have to work out how utilise the gift that's staring us in the face.
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If you look at the universe, the most abundant atoms are hydrogen, helium, oxygen and carbon. The hydrogen and helium have been around since early in the universe, while oxygen and carbon come from stars.
Oxygen is number three because it is a very stable nucleus. Maybe fusion should be trying to make stable end products like oxygen from carbon and nitrogen. Or another approach is we should be trying to make iron, so the output is easier to control. Iron is last exothermic energy formation atom with lower grade energy output, which is easier to control.
If we start with isotopes of hydrogen and helium we form unstable products which are not as common to the universe. Stars tend to use these as precursors. If we make the most common elements, we get to take advantage nuclear stability.
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If you look at the universe, the most abundant atoms are hydrogen, helium, oxygen and carbon. The hydrogen and helium have been around since early in the universe, while oxygen and carbon come from stars.
Oxygen is number three because it is a very stable nucleus. Maybe fusion should be trying to make stable end products like oxygen from carbon and nitrogen. Or another approach is we should be trying to make iron, so the output is easier to control. Iron is last exothermic energy formation atom with lower grade energy output, which is easier to control.
If we start with isotopes of hydrogen and helium we form unstable products which are not as common to the universe. Stars tend to use these as precursors. If we make the most common elements, we get to take advantage nuclear stability.
The problem with using larger atoms is that the energy required to get the nuclei together increases dramatically with the number of protons (the electrostatic repulsion between two helium nuclei is four times greater than between two hydrogen nuclei). Stars that are insufficiently large will only fuse hydrogen into helium, and stop there. Only once a critical mass is attained will heavier elements be synthesized.
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If you look at the universe, the most abundant atoms are hydrogen, helium, oxygen and carbon. The hydrogen and helium have been around since early in the universe, while oxygen and carbon come from stars.
Oxygen is number three because it is a very stable nucleus. Maybe fusion should be trying to make stable end products like oxygen from carbon and nitrogen. Or another approach is we should be trying to make iron, so the output is easier to control. Iron is last exothermic energy formation atom with lower grade energy output, which is easier to control.
If we start with isotopes of hydrogen and helium we form unstable products which are not as common to the universe. Stars tend to use these as precursors. If we make the most common elements, we get to take advantage nuclear stability.
The hurdles for fusion power is two-fold: Control and sustainability. Sustainability means that the reaction produces enough energy to offset the energy needed to maintain it. That's been the sticking point so far. We have been able to maintain controlled fusion, but haven't been able to get to the break even point yet. Heavier isotopes give less energy for more effort, and thus are going in the wrong way for what we need.
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The fission fusion bomb i believe is a way to increase yields by the hydrogen moping up the unused discharge from the fission , this intern can ignite another fission reaction shell, and then another hydrogen, and so on. (Therefore it can continue forever and you can make a doomsday bomb) I do not think that you gain more out from the hydrogen than you put in, you have to have the fission material to start with.
That said you gain qlot of energy from the fusion shell, so a few sprinkling of hydrogen in a radioactive source you should be able to grenerate power by that.
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a few sprinkling of hydrogen in a radioactive source you should be able to generate power by that
The fission/fusion bomb works because the incredible temperature and pressure of the fission explosion is sufficient to trigger hydrogen fusion (which requires temperatures of millions of degrees to get started).
However, for controlled power generation, fission reactors typically only work at temperatures of 300C and 150 atmospheres of pressure.
This is far from the conditions necessary to trigger hydrogen fusion.
So you would have to say that putting some hydrogen isotopes in the fuel of a nuclear fission reactor will not boost the output of the fission reactor, or allow us to reach controlled fusion power.
For typical conditions inside a fission reactor, see: https://en.wikipedia.org/wiki/Pressurized_water_reactor#PWR_reactor_design (https://en.wikipedia.org/wiki/Pressurized_water_reactor#PWR_reactor_design)
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a few sprinkling of hydrogen in a radioactive source you should be able to generate power by that
The fission/fusion bomb works because the incredible temperature and pressure of the fission explosion is sufficient to trigger hydrogen fusion (which requires temperatures of millions of degrees to get started).
However, for controlled power generation, fission reactors typically only work at temperatures of 300C and 150 atmospheres of pressure.
This is far from the conditions necessary to trigger hydrogen fusion.
So you would have to say that putting some hydrogen isotopes in the fuel of a nuclear fission reactor will not boost the output of the fission reactor, or allow us to reach controlled fusion power.
For typical conditions inside a fission reactor, see: en wikipedia hydrogen bomb
Bear in mind were discussing the controlled fusion of atoms with a net gain in energy, that isnt achieved as of post time. I do not know what they can accomplish , so a dual reaction device seems as plausable as anything else. And if they can do it with less radiatioactive waste it would be good. Theres one reason that uranium was pursued by the governments over thorium or other and that was weaponisation. The resources went into the bomb !
Anyway this is getting into politiks