New insights on fusion power

[OKIsItJustMe]

http://web.mit.edu/newsoffice/2008/fusion-results-tt120...

New insights on fusion power

David Chandler, MIT News Office
December 3, 2008

Research carried out at MIT's Alcator C-Mod fusion reactor may have brought the promise of fusion as a future power source a bit closer to reality, though scientists caution that a practical fusion powerplant is still decades away.

Fusion, the reaction that produces the sun's energy, is thought to have enormous potential for future power generation because fusion plant operation produces no emissions, fuel sources are potentially abundant, and it produces relatively little (and short-lived) radioactive waste. But it still faces great hurdles.

"There's been a lot of progress," says physicist Earl Marmar, division head of the Alcator Project at the MIT Plasma Science and Fusion Center (PSFC). "We're learning a lot more about the details of how these things work."

The Alcator C-Mod reactor, in operation since 1993, has the highest magnetic field and the highest plasma pressure of any fusion reactor in the world, and is the largest fusion reactor operated by any university.

…

A version of this article appeared in MIT Tech Talk on December 3, 2008 (download PDF).

[TheWraith]

1. Why aren't we funding the guys who say they're 5 years away from commercialization?

The Polywell is still out there, folks. They want $200 million to build a 100 megawatt testbed, and prior to his death late last year, Dr. Robert Bussard seemed certain that in 4-6 years the technology would be proved out and ready for widescale deployment.

[scubadude]

2. Looks like there is some action in this area from the Navy

They were the organization that funded Bussard and monies are still being allocated.

Here is a link to where the discussion resides: http://www.talk-polywell.org/bb/index.php

Scuba

[TheWraith]

10. I've been there. Right now it's apparently just "placeholder" money from what I hear.

Basically, enough to keep the company running until somebody makes a decision whether to fully fund them.

[Occulus]

22. Thak you; I was just going to post that

Here's a picture of their most recent iteration of the Polywell:



WB-6, using helium as a fuel for testing purposes

[FogerRox]

43. Thats WB-7

[Terry in Austin]

3. Fusion: Oh, boy -- unlimited energy!

...and unlimited population growth as a result.

Careful what you wish for. It's just fool's luck that practical fusion technology has always been "20 years away," and is likely to stay that way for some time to come. I just hope we get smart enough to handle it before we get smart enough to make it.

[OKIsItJustMe]

4. "Unlimited energy" does not result in "unlimited population growth"

Check out the population graph I posted earlier:


"Developed regions" have much more energy, yet their population growth is slower.

[Terry in Austin]

5. Nice graph

Fits the "development" narrative that's so dear to us.

Not sure that any of it makes a very compelling case, however. Lots of extrapolation happening there, from data that's more or less on an anecdotal scale.

The popular interpretations of these demographic blips in "advanced" countries tend to be pretty light on actual population dynamics, citing individual behavioral reasons like a higher level of education for women, etc. However, one of the basics for a population -- any population, be it yeasts or humans -- is this: "energy in, numbers up."

If you haven't already made up your mind about this, you might be interested in looking at the work of Hopfenberg and Pimentel, particularly "Human Population Numbers as a Function of Food Supply."

Some clips:

...Some contend that fertility is under cultural and economic control (Marchetti et al., 1996) and that science and technology will solve all future food problems (Ausubel, 1996).

...{however,} the data overwhelmingly establishes that increasing the amount of food available to the population of any species leads to an increase in the population of that species ...evidence that food surplus explains, i.e., is causally related to, human population increases.

[OKIsItJustMe]

7. One more time

Check out relative figures for "fertility rates."
http://en.wikipedia.org/wiki/List_of_countries_and_terr...

Tell me again that population growth is driven by power (or by food supply or money.)

[Terry in Austin]

14. Okay

Tell me again that population growth is driven by power (or by food supply or money.)

Population growth is caused by surplus food. (see upthread).

Humans have the trick of turning external energy into food, so for human populations, energy=food. As long as energy is abundant, you can bet that enough of it will be put toward creating and maintaining a generous food supply, just as we have done throughout the petroleum age.

Please note that your graph still shows population growth -- there's a reduction in the rate of growth in some localities, okay, but it's still positive for the world as a whole.

When data like this is presented as a favorable population-management argument, the article of faith behind it is that someday the whole world will have a per-capita GDP matching that of today's "advanced" nations and therefore turn population growth rates negative. The only trouble is that this can't happen, as it would take several Earths' worth of resources.

[Nihil]

27. That is the point that some people don't seem to grasp ...

> When data like this is presented as a favorable population-management
> argument, the article of faith behind it is that someday the whole world
> will have a per-capita GDP matching that of today's "advanced" nations
> and therefore turn population growth rates negative. The only trouble
> is that this can't happen, as it would take several Earths' worth
> of resources.

Yes, the end-state where everyone is enjoying the best level of current
lifestyles would result in zero or even negative population growth but
that is a pure unsupported fantasy, not only from the resources point above
but also from the totally unsupported assumption that human greed would also
have been magically eradicated from the species (hence that the magical
extra Earths of new resources would be fairly shared around).

Still, my last point would probably be dismissed as "unduly pessimistic"
and "lacking hope/faith/trust in the better side of humanity" so stick to
the KISS principle and the FACT that there simply aren't enough Earths of
resources to match the demand of that "ideal world".

[GliderGuider]

13. The assumptions inherent in that graph render it useless.

In order to realize the shape of that graph you have to assume at least:

• There will be 3 to 5 times as much energy available to civilization in 2100 as there is today.
  
• There will be sufficient material resources (metal, water, wood) to satisfy a first-world lifestyle for that many people.
  
• There will be enough food produced, in the face of a degrading land base and dropping water supplies.
  
• Climate change won't take a bite out of feed production.
  
• The accelerating loss of biodiversity doesn't doom some species that turns out to be critical for our survival (honeybees?)
  
• That civilization doesn't reach a level of complexity that cascading technological failures start to appear(or at least a Tainteresque diminishing of marginal returns on complexity).

Depending on Benign Demographic Transition to cure our ills seems Quixotic to me.

I think the present number of people is already too much for the planet to support over the medium term given that we're already in overshoot. I find it more likely that some limiting factor or factors will appear over the next 20 years. What that might be is an open question, as is the question of whether our population will merely stabilize near our current number for a while, or will actually begin to drop off as a result.

My money is on the world population rising to about 7.5 to 8 billion within 10 years, stabilizing there for a decade or so, then beginning to drop. The rate of decline, and the "final" number of people in that scenario is entirely unknowable. But I definitely don't believe we'll see the curve in your graph.

[Terry in Austin]

15. Benign Demographic Transition

Nicely put, sir! A great term -- I hope you don't mind if I use it now and then.

It points up the magical/wishful thinking that still goes on in many of the "scientific" treatments of population issues.

[GliderGuider]

19. "Demographic Transition Model" is the standard term

The adjective "benign" was added by Garret Hardin in his book "Living Within Limits" to indicate ZPG that was achieved through falling birth rates. That was to differentiate it from "malign demographic transition" where a stable population is achieved through rising death rates. He also noted that demographic transition was strictly a series of observations, rather than being a scientific theory with predictive capacity (i.e. nobody really understands the underlying mechanism that seems to link affluence to falling fertility.

I think it's more probable that our population will eventually stabilize through the malign version rather than the benign version.

[Terry in Austin]

25. Interesting terms

The "benign" falling-birthrate scenario is certainly appealing, but as you say, probably Quixotic. Getting that to happen would be an unprecedentedly massive project of social organization. Wouldn't bet the farm on it, certainly.

Come to that, ZPG is a modest goal, considering that we're well into overshoot at this point, and the crucial long-term issue is having a population that's within the "natural" (i.e., non-subsidized) carrying capacity of the planet. The high end of the range of estimates I've seen is 3 billion or so.

I don't believe it's too soon to recalibrate our thinking from "ZPG" to "NPG" (negative population growth). Lest the cornucopians get too alarmed, this process doesn't necessarily need to be catastrophic.

Just to take a first stab at the numbers, a -0.75% NPG rate would get us to about 3.4 billion by the end of the century. The big management problem would be to parcel out diminishing energy resources shrewdly enough to keep people fed. But that's much less of a management problem than trying to dictate who gets to reproduce and who doesn't.

It seems likely that the demographic transition will be a messy combination of "benign" and "malign," with a definite tilt toward the latter. Populations under stress have reduced birth rates, so we can expect the birth rate to go down a certain amount, independently of any social or legal intervention. The death rate, well, it certainly won't be going down, given those same stresses. Let's keep in mind, though, that this doesn't mean that people are dropping like flies in the streets; more likely, it will be in the form of reduced life-expectancy. The experience in Russia in the 1990's is a case in point.

The -0.75% NPG rate in this example represents half of the current birth rate and double the current death rate. Not a cheerful scenario, to be sure, and it's easy to be cavalier with the numbers. But neither is it the catastrophic dieoff that some envision -- or accuse others of envisioning.

Thanks for the pointer to Hardin. I'm especially glad to note the point about observations, predictive capacity and the tenuous link between affluence and falling fertility.

[TheWraith]

17. You're right. It's hopeless. The only solution is mass suicide.

Seriously, think about what you're saying. Fifty years ago, the civilization we maintain today would have been a flight of fancy. To suggest that 100 years from now we won't be able to do these things because we can't do them now?

[GliderGuider]

20. If you say so. I don't know why you think suicide is the only answer, but OK.

Of course we will be in a different place in 50 years than we are today. However, the assumption of infinite growth in a finite environment (let alone one in which all major biophysical trends seem to have gone negative) is a poor basis from which to predict success. In fact, it's a faith-based approach -- similar to the belief that house prices would rise forever.

[Terry in Austin]

21. Mass suicide? Oooh... sarky!

And a touching faith in the Magic of Civilization.

The only magic is that we had an inheritance of fossil fuel that we've just about finished squandering. To imagine a straight-line, ever-upward path of "progress" over another 100 years without that energy subsidy is a flight of fancy, indeed.

Meanwhile, back down to earth, our species is confronting a milestone in its maturity: the sobering fact that our population as a whole doesn't behave much differently than a population of yeasts. The excess of our own numbers is a "brick wall" issue. It's dismaying and humbling to think that we don't have a "solution" for it, but then neither do we have a solution for, say, nasty weather.

I don't have the answer, and I don't think anybody else does, either. I think that's really the only honest answer. We like to think of these situations as problems that can be solved, and that's true for many situations. But not all. A solution means that the problem goes away. Otherwise, it's a predicament, meaning that you just adapt as best you can -- suicide being the least adaptive option, of course.

I doubt if the overpopulation problem will go away as a result of anything we do. More accurately, then, it's an overpopulation predicament. We adapt as best we can, while Nature takes its course in balancing our numbers with the carrying capacity of the planet.

It's a blow to the human ego, true, but all this techno-triumphalism in the name of "civilization" has its limits, and it's becoming increasingly clear that those limits extend only as far as our endowment of fossil fuels.

[TheWraith]

24. You're making an argument based on pessimism, not facts.

Your assumptions are not supported by science. I suggest you google "dwarf wheat." It might help enlighten you as to the degree to which pessimism has traditionally been wrong.

[Terry in Austin]

26. "Pessimism has traditionally been wrong"

I see. That's your take on science?

Enlightening, indeed!

Sorry, but we're moving from science to personal metaphysics, and that's a dispute with no future.

So -- how 'bout them Cowboys, anyway?

[TheWraith]

6. Actually no, that's completely and totally wrong.

Unlimited energy means unlimited civilization. Technological progress and the advance of civilization follows a very close curve versus the amount of energy required per person. Also, as a rule, the higher a degree of civilization and modernization, the slower the population growth rate. It's no coincidence that the least modern areas of the world are those that show the highest rate of population growth.

[Terry in Austin]

8. Fine. Make the case, then.

as a rule, the higher a degree of civilization and modernization, the slower the population growth rate.

Where, exactly, is this rule established?

I know that it's a sacred tenet of "modernism," but its claim to any factual basis doesn't go much beyond the anecdotal. Some downward blips in fertility in some of the more industrialized countries, but it's shaky business to generalize from that.

[OKIsItJustMe]

9. Please check my posting

(above)

I've heard it said that the best "birth control" is the expectation by a mother that her children will live to adulthood.

http://www.scienceblog.com/community/older/archives/L/1...

…

As indicated in the table below, the pattern of lowest fertility among the most educated women holds for all societies. In every country examined, women with 10 or more years of schooling have much lower fertility than women who have not attended school. The largest difference in fertility rates among countries of a region occurs in Latin American, where the rates range from 3 to 5 children.

Fertility rates as a factor of education are not uniformly related to the level of development. The strength of that association varies significantly among countries. This suggests that such factors as socio- economic development, social structure and cultural context also play a role. The impact of individual schooling, which is generally weak in poor, rural and mostly illiterate societies, tends to be greater in more prosperous societies.

…

[TheWraith]

11. It's established in this thing called reality.

Take a look at any of the industrialized nations. You know what their population growth is? Next to nothing. Most of the population growth they do have is from immigration, not reproduction. Fertility isn't the measure of population growth, population growth is.

There is and has been, throughout history, a marked link between the advancement of a culture, its education and modernization level, and a decrease in the birth rate.

[Terry in Austin]

12. Slight problem

We're talking global population growth, and as far as I know, that figure is unaffected by immigration.

When fertility rates are positive, population grows. For all our "moderun civilization," fertility rates remain positive, and as long as they do, population will grow. It's this thing called "math."

The argument that "advancement=population decrease" is a weak one. To hope that Modernism will somehow turn fertility rates negative is sort of a faith-based extrapolation of the data presented, and a rather desperate interpretation of it.

There's much stronger evidence that as long as there is a surplus of food, population will continue to grow. See Hopfenberg and Pimentel, also cited upthread.

[TheWraith]

16. Your assumptions are bogus.

Your entire argument is based on the premise that if the population is growing ANYWHERE, it means that the population is growing EVERYWHERE.

Look at population numbers country by county. Industrialized nations are holding still in population. Population growth happens in places where the standard of living is lower and mortality rates are higher.

Your argument cuts across decades of clear and unmistakable scientific data: that when quality of life improves, survivability improves, and education improves, the birth rate drops sharply. The same thing is present right here in the US. The places that show the biggest population increase are rural and inner city areas where education is lower and quality of life is lower.

And frankly, I'm getting tired of the people around here who seem to think that they only "sustainable" society is one that lives in huts, eats bark, and is just as anti-science as the most fanatical right-wingers.

[Terry in Austin]

18. So tired? Get some rest

I'm getting tired of the people around here who seem to think that they only "sustainable" society is one that lives in huts, eats bark, and is just as anti-science as the most fanatical right-wingers.

I don't know who "the people around here" are that make that argument -- I certainly don't -- but yours seems to have petered out rather quickly. Surely you've got more than dismissive labels and straw men, hmmm?

Actually, my argument is that if "the" population is growing globally, then it's, well, growing globally. Surely, that's not too hard to grasp.

The larger issue is this: the world is getting overpopulated, so what is to be done about it (if anything)? One popular response is in the "advanced countries" data so often cited, along with the argument that development will take care of the population problem. I'm not convinced by this argument. I think it's weak and misses the point. YMMV.

[TheWraith]

23. You can find the argument "weak" all you like. Your opinion doesn't override science.

Again: The overwhelming body of scientific research and practical experience shows that as a nation becomes more developed, population growth goes down. Global population growth is irrelevant when there's such a wild variance in the conditions that control growth. It's like saying that the poverty rate in Brunai affects crime in London. This is one of those simple cause and effect things.

[NNadir]

29. Of all the energy fantasies, the fusion fantasy is probably the worst.

Most of the cute energy fantasies, solar, wind, what have you, produce actual, if trivial, energy.

Fusion has never done any such thing. It doesn't work. If it did work, it would need a fisson infrastructure to survive and wouldn't be (most likely) nearly as safe nor as clean as fission, since nothing is as safe or as clean as fission.

It's worse than listening to all of the "world's largest solar" posts, since it is just more denial and fantasy in the face of dire reality.

[joshcryer]

30. Why would it need a fission infrastructure to survive?

[Dead_Parrot]

32. Most research is aimed at D-T fusion...

(deuterium-tritium): It requires either a fission reactor to supply the tritium, or an <insert magic here> techno-fix called a tritium breeder which nobody knows how to make yet.

[janap]

33. tritium

The Canadians make tritium by the boatload. It is a product of heavy water nuclear mediation in their Candu reactors. I hope you are not an anti-nuke because you are not that well informed.

[Dead_Parrot]

35. Err... What?

So to recap:
NN: Fusion requires fission reactors
JC: why?
DP: Most fusion projects use tritium, which is made in fission reactors
janap: But Canadians make tritium in fission reactors! You dumbass!

Y'know, if I close my eyes, I can almost see the half empty bottle of Jim Beam next to your keyboard. Cool.

[janap]

37. got it yet

No, that is where a fusion reactor gets the tritium to startup with. After statup they breed tritium in their first wall using lithium 6 salt as follows:

L6 + n -> h4 + h3 + 4.8MvE

[Dead_Parrot]

41. Last time I looked...

...nobody had actually built a breeder blanket, hence the <insert magic here> comment. Are you saying this particular problem has been solved?

[Dead_Parrot]

31. Polywell isn't aiming at tritium...

...They're going for p+¹¹B -> 3⁴He, which saves all that mucking around inventing breeder blankets. I'm skeptical that they can get over unity, but it is a nice idea.

Of course, thinking that they will get it working and scaled up to EJ levels in the next decade requires the sort of belief you only find in Salt Lake City.

[janap]

34. get the facts right.

No boron hydrogen fusion.

[Dead_Parrot]

36. That's not a fact

It's not even a coherent sentence. No boron hydrogen fusion what? No boron hydrogen fusion is possible? No boron hydrogen fusion will overcome bremsstrahlung losses? No boron hydrogen fusion can make me miss a good party?

[janap]

40. LEARN

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

[Dead_Parrot]

42. Yes, I know what that is

It's the phrase "No boron hydrogen fusion" that I'm having trouble understanding.

[janap]

28. Polywell fusion bust

They say that the devil is in the details. It certainly is with the Polywell fusor. This and the other fusors are going for the fusion of boron and hydrogen to avoid the production of neutrons. Those devil neutrons, those little devils that make the anti nukes turn green. The B-H fusors will never reach energy break even at one billion degrees it will take to reach B-H fusion. Someone will fuse tritium and deuterium with all those high energy plutonium producing neutrons but that is just as bad as those devil fission reactors with all that proliferation danger. Oh well! Back to the solar panels.

[conscious evolution]

38. I thought hydrogen was a by product of fusion in the Polywell reactor?

[janap]

39. No helium

No. Three helium atoms and 8.7 MeV of energy

[FogerRox]

45. dependant on fuel used

[FogerRox]

44. Fusors use wire grids, Polywells dont use wire grids, they are not fusors

You do know what a fusor is, dont you?