THE Fusion: Pros & Cons Thread (merged)

[Ferretlover]

I have to admit, ITER (the new experimental fusion reactor due to start construction next year) really did act as a hope in my mind, until I read a feature about it in Saab magazine today.

According to the lead scientist, whilst it should produce 10 times as much energy as it consumes (about as much as oil is today), it will not be until 2050 when commercial reactors finally become available. By that time, oil gas & coal will be all but fully depleted. Damn.

[MarkR]

Unfortunately, fusion physics is hard.

ITER is not meant to be a complete power plant - just a small prototype reactor (albeit much bigger than ones to date) designed for the study of plasma physics. The eventual aim is for it to sustain a fusion reaction in a 'sub-critical' mode (the reaction is not self sustaining, but requires constant injection of energy into the reactor, although the reaction does produce net energy).

However, the ITER project will have no way of harnessing the energy from the reactor. Actually extracting energy from the reactor will have to wait for another project. The subsequent project, called DEMO, is basically meant to be a proof of concept power plant - and will feature a fusion reactor, and power conversion system to produce about 500 MW of electricity. Construction of this project is not anticipated to start until 2030 at the earliest, and is expected to have a 10 year lead time.

Even by 2050-2060, given the immense complexity and scale of the engineering involved, I am unconvinced that fusion reactors would be an economically (or indeed energetically) viable project. I do not think we will see any profitable plants for probably a couple of decades after that.

[fred2]

More than 10 years ago I worked at JET, the European Fusion Project, albeit in a very minor role (and nothing to do with the physics). I remember ITER and DEMO being planned as the next 2 phases prior to a commercial reactor, and with similar timescales to those above. So at least it hasn’t slipped significantly.

In an international crisis situation - as oil may well turn into - a lot can be achieved when major developed countries such as the US truly focus on task. E.g. consider what the Manhattan project achieved in 4 years.

I would expect interest and investment in fusion to increase massively once the oil shortage starts to hit, and hopefully these timescales may shorten, though not dramatically.

[goldfishbowl42]

I don't have a link or source but I remember reading about a year ago that the US had pulled its funding for ITER because they weren't happy that the proposed site for it was either France or Japan.

Thats the last I heard, Does anyone know if the US is still funding it now?

[MarkR]

I don't have a link or source but I remember reading about a year ago that the US had pulled its funding for ITER because they weren't happy that the proposed site for it was either France or Japan.

Thats the last I heard, Does anyone know if the US is still funding it now?

It's a bit of a complicated story:
You're right. ITER was struggling, so the US decided to "go it alone" with another project called FIRE.

It didn't take long before they decided that FIRE was likely to be wasted effort. They decided to axe FIRE and focus their attention back on the multi-national ITER project.

[MarkR]

Sorry, forgot the link:

http://www.newscientist.com/news/news.jsp?id=ns99996225

[Repent]

It seems to me to be odd that all the work on fusion energy has been focused on fusing hydrogen in helium or other hydrogen isotopes?

I have read that in Stars for example; hydrogen fuses into helium, helium fuses into lithium, lithium fuses into Beryllium- ect until the process reaches lead and then stops as the process can no longer sustain itself.

If we were to use lead as a start point for fusion energy reactors- wouldn't the natural restraints of fusion beyond this point inhibit the dangers which have impeded progress with hydrogen fusion?

I'm definitely no expert- but I don't see why we have to use hydrogen (or its isotopes) exclusively in the pursuit of Fusion energy reactors?

[Terran]

The higher the atomic mass the larger the amount of energy it needs. Our suns hydrogen can undergo fusion from hydrogen to helium. Once it fuses out of hydrogen, the helium undergoes fusion. The fusing of the helium causes the sun to go into a supergiant once it reaches the end of it's life.

In larger hotter stars, they undergo fusion until they reach the element Iron, but usually stop after that.

Imagine the amount of energy you must put in to fuse lead, into bismuth? It's beyone nothing more than theorical physics.

[Devil]

Yeah, sure!

[MarkR]

Fusion in stars stops at Iron, expect during catastrophic 'nova' or 'supernova' explosions ignited by overwhelming gravitational collapse.

There is good reason why this is the case. Fusion that creates elements heavier than Iron (number 26) actually absorbs energy (in the same way as generating hydrogen from water absorbs energy).

On the other hand, the heavy elements such as Uranium, are the opposite. So much energy was absorbed from the fusion reactions that formed them, that it is begging to be let out again by nuclear fission.

A quick examination of the periodic table shows that lead is far, far too heavy to be worth fusing.

[Repent]

Sorry for my ignorance - I withdraw my post on this article.

[MonteQuest]

In the arena of public discussion the pessimistic camp on the future of oil production is at a certain disadvantage, as people, particularly during good economic times, cannot fathom that storm clouds may be forming. Furthermore, it is generally more difficult to obtain a sympathetic hearing for a worrisome viewpoint than an optimistic one, as belief in progress, both technological and societal, seems to be universal. But I suggest we take it a step further, and take a hard look at what we think we want to happen, and why.

I admit to being an idealist. I would surely like to envision a world powered down to a sustainable level that wouldn't entail a constant crisis management, but realistically, I know it is futile. But, then again, it doesn't detract from the notion that a little backwards is better than more forward. To me, the issue is no longer how to solve the peak-oil energy crisis, but how to cope and live with it.

Now, this should get a response: To me, given our current cultural mindset, the worse thing that could happen would be to find some inexhaustible new source of energy. We would doom the human race to extinction by making the planet uninhabitable through our wanton consumption. Now if we developed fusion and also reverted back to the population of the mid-1800's, did away with the "throw-away" society, recycled and downsized everything, instituted de-centralization, embraced environmental constraints, and generally practiced a conservation ethic, then that would be a good start—even in an entropy world where it all ends anyway.

[seb]

I will answer about the predictible future about nuclear fusion as an infinite source of energy. I work in inertial laser fusion as a mathematician in numerical simulation.

But first I would like to talk about very basic thermodynamics because many use the word entropy around here and the only use of this word is supposed to justify so many things...
The first principle (conservation of energy) is most of time well used. For instance you will not get more energy from hydrogen burning than you used electrical energy to seperate oxygen and hydrogen in H2O (water).
The second principle is "the entropy of an isolated system can only increase". But you can diminish the entropy of a system using external energy... Earth is not an isolated system. Yes, the Sun gives Earth lot's of energy and the Nature use it quite well (photosynthesis for instance) to become a bit ordered. Simple example : you cut a tree, you burn it (then you got energy, you are happy), CO2 goes in the atmosphere, at the place you cut your tree another tree grows (photosynthesis) and capture roughly the same amount of CO2 you produced. This process transforms solar energy in thermel energy to heat your house. Of course YOU created entropy burning your tree, but Nature used solar energy to put everything in order. Conclusion : the entropy of the solar inscreased but this does not look like a big problem for now...

About fusion, this is still a long way to go. People laughing at scientists say it is always predicted to be ready in 50 years and this prediction holds for... 50 years now. They are right, it is more difficult as expected and the light at the end of the tunnel is still far but we make progress. But nuclear fusion used at a world scale as a major energy output... hmmm, 50 years why not but sounds optimistic. But to be honest, nobody can anticipate scientific progress for the next 50 years, so we'd better not predict anything. One thing for sure, it is at least a decade to produce just a bit of energy with controled fusion in a lab with hundreds of specialists around it. Such experiments frequency is low too and we are far far from industrial applications.
Finally, we need scientists (good physicists specially) but people who chose science are turning very rare recently.

Seb

[Falconoffury]

The root of the problem is human nature. In the 150 years that we have been using oil, we have advanced our technology, but not so much ourselves. We need to evolve to a point where we can be responsible with our growth and honest about our failings.

[MonteQuest]

The second principle is "the entropy of an isolated system can only increase". But you can diminish the entropy of a system using external energy... Earth is not an isolated system.

I guess the point of this thread went over your head, huh? Your response has nothing to do with it. But while I am at it, Second law applies to open, closed, and isolated systems. In the first two, entropy can be reduced, but only by creating even more entropy somewhere else. You fail to understand 2nd law if you feel this is not an issue. Your analogy was too simplistic. How did you cut the tree? What tool did you use? Chainsaw? Axe? How was it made? What materials were required? How much fuel? How did you transport the wood? A lot of energy conversions went on here to just burn a tree, and that increased a lot of entropy in the environment, which is a big problem these days.

[basketballjones]

Now, this should get a response: To me, given our current cultural mindset, the worse thing that could happen would be to find some inexhaustible new source of energy. We would doom the human race to extinction by making the planet uninhabitable through our wanton consumption. Now if we developed fusion and also reverted back to the population of the mid-1800's, did away with the "throw-away" society, recycled and downsized everything, instituted de-centralization, embraced environmental constraints, and generally practiced a conservation ethic, then that would be a good start—even in an entropy world where it all ends anyway.

I couldn't agree more. Humans are by nature wasteful and ignorant. While some people would argue that we are much more evolved than animals, i suggest that we are in some areas, but we are not in most areas. We are conscious of our bad decisions but if we can live with it (eg smoking, pollution, ravenous consumption of oil) then do not change our ways. Most of the time humans choose a path of least resistance and a path of least effort.

Without fusion, we might narrowly avoid causing the extinction of most of the complex forms of life on the planet. With fusion, i suspect it might be a certainty although it may just take a while longer. A change from hydrocarbons to a much cleaner form of energy would reduce the amount of global warming, ozone destruction and other environmental distasters humans are directly responsible for, but for the exponential growth in human population would only server to put additional pressure on what food supplies we have. Peak food has been well documented.

[jato]

I would say (being a doomer): Don't worry; fusion energy won't arrive at all because it is already too late. It is the other, more destructive type of fusion devices I worry about.

but Nature used solar energy to put everything in order.

This is interesting. What is this Nature thing? How did it get here? How is it able to combat entropy? Nature as a reverse entropy vector?

[rowante]

Crikey, enough with the entropy business! There are plenty of threads already...

[jato]

Crikey, enough with the entropy business! There are plenty of threads already...

So if humans starve to death over the next 100 years due to a lack of fossil fuels and the population goes from 7 billion down to 1 billion, what mechanism will be more at fault? Entropy or Mother Nature?



What if people cut down and burn all of the trees becuase we ran out of fossil fuels? Then what happens? Will people burn tires to stay warm at night?

[seb]

But while I am at it, Second law applies to open, closed, and isolated systems. In the first two, entropy can be reduced, but only by creating even more entropy somewhere else.

My last answer about entropy since I suspect it is useless. Ok, physics is a bit more complex than basic classical thermodynamics. Sorry, I might look a little bit aggressive this way...
For instance, radiation cooling can reduce the entropy of a system. Of course it is not in book of thermodynamics because it is not thermodynamics. There are other ways that pure material transport to move entropy somewhere else. Now if you claim that Earth does not radiate, ok you are right.
Just consider how much entropy (and energy of course) come from Earth itself due to internal core process (heavy nucleii desintegration for example) or simply because of moon gravitational effect (yes, the oceans move every day due to that and this movement is a bit more that what it takes to cut my tree), and then you will see that natural production of entropy (not only energy) occuring after millions of years is far much more that what human beings produced. This entropy did not accumulated on Earth I guess. And if it did, then we add a neglectible amount to it. Entropy may look like a big word but it is not a problem for Earth itself.

Seb

PS: usually entropy is used to justify that complex process are not 100% efficient. Going to statistical physics (the mother of thermodynamics) we understand a bit more since entropy is defined mathematically from particule distribution. But this is related to temperature and temperature is affected by radiation which is not considered in statistical physics.