Tokamak fusion

[Relick]

http://www.independent.co.uk/news/science/one-giant-leap-for-mankind-13bn-iter-project-makes-breakthrough-in-the-quest-for-nuclear-fusion-a-solution-to-climate-change-and-an-age-of-clean-cheap-energy-8590480.html

Just read this article, so it looks like we might finally be pushing forward with getting fusion energy.

Although, it does bring up a question to the wannabe physicist. How can we possibly maintain 150,000,000 degrees Celsius with magnets and concrete? I could wikipedia it but then again this sounds look a good discussion for what the future holds for energy. What do you guys think will be used in the next 100, maybe more years?

[Grove]

Hi, so regular fission nuclear reactors heat water and then spin turbines, but how do fusion reactors collect energy?

[Person012345]

The same way.

[Grove]

Then, how is it more efficient, it's the same stuff.

[Person012345]

Because fusion is a more efficient way of getting energy than fission. More energy is released in a fusion reaction than a fission one, for a given amount of fuel (I guess). So it boils more water and gives more power. Plus you have all the other benefits of fusion over fission (for example not creating a bunch of highly toxic waste, only a few irradiated parts that IIRC have relatively short half-lives).

For the record, fossil fuel power plants work exactly the same way in most cases. But burning is a less efficient reaction than fission.

[Grove]

Oh, I guess we need to invent more a efficient way to turn mechanical energy into electric energy than the current turbines.

[Scotius]

And uranium is rare compared to deuterium. There is enough deuterium in Earth's sea water to power our civilisation for thousands of years. If we'd ever get to burning helium-3, it will be millions of years before we run out of power.

[Person012345]

Oh, I guess we need to invent more a efficient way to turn mechanical energy into electric energy than the current turbines.

Well, I'm sure power companies would welcome such an invention. But steam turbines are pretty good, and have stood the test of time.

[DuckZero]

And uranium is rare compared to deuterium. There is enough deuterium in Earth's sea water to power our civilisation for thousands of years. If we'd ever get to burning helium-3, it will be millions of years before we run out of power.

There isn't all that much helium-3 to go around, and it might not even be energetically viable to mine the majority of it.

Deuterium-tritrium is good because you can breed tritrium from lithium while the reactor is running. You can use the lithium as a coolant too.

Plus it has a factor of 10 higher peak sigma-v (basically reaction rate) at a much lower temperature than deuterium-helium-3 fusion, so DT reactors can be smaller and cooler.

[nyrath]

Actually there is a better way to convert fusion released energy into electricity than using the inefficient boiler system used by fission reactor. You can send the plasma from the reaction through something called a "magnetohydrodynamic generator" (MHD generator) and get electricity out of it. Look up MHD generator in Wikipedia.

[K^2]

So we're only a couple of decades away from sustainable fusion energy. Business as usual.

[Rune]

The same way.

Some don't. The Polywell concept, if it is able to burn p-B11 fuel like its researchers claim it should, is inherently a direct conversion device. Meaning it takes energy away from the charged alphas by decelerating them in a magnetic field and inducing high-voltage current than you afterwards condition and pipe to wherever you want. Very efficient, considering 80% of the reaction's energy is contained in those alphas.

It's when you have to deal with neutron-producing fusion reactions when you have to make do with boiling water. And there's always the concept of magnetohydrodinamic conversion, though I must admit I haven't looked into that and might even be getting the name wrong. Something to do with building a "turbine" out of magnetic fields and working with plasmas as fluids.

Edited April 29, 2013 by Rune

[Aladran]

From Wikipedia, TOKAMAK might not be the way to go...

Polywell

The ITER project confronts numerous technically challenging issues. French Nobel laureate in physics, Pierre-Gilles de Gennes said of nuclear fusion, "We say that we will put the sun into a box. The idea is pretty. The problem is, we don't know how to make the box."[37]

A technical concern is that the 14 MeV neutrons produced by the fusion reactions will damage the materials from which the reactor is built.[38] Research is in progress to determine how and/or if reactor walls can be designed to last long enough to make a commercial power plant economically viable in the presence of the intense neutron bombardment. The damage is primarily caused by high energy neutrons knocking atoms out of their normal position in the crystal lattice. A related problem for a future commercial fusion power plant is that the neutron bombardment will induce radioactivity in the reactor material itself.[39] Maintaining and decommissioning a commercial reactor may thus be difficult and expensive. Another problem is that superconducting magnets are damaged by neutron fluxes. A new special research facility, IFMIF, is planned to investigate this problem.

A number of fusion researchers working on non-tokamak systems, such as Robert Bussard and Eric Lerner, have been critical of ITER for diverting funding from what they believe could be a potentially more viable and/or cost-effective path to fusion power, such as the polywell reactor.[40][41] Many critics accuse ITER researchers of being unwilling to face up to the technical and economic potential problems posed by Tokamak fusion schemes.[40]

In 2005, Greenpeace International issued a press statement criticizing government funding of the ITER, believing the money should have been diverted to renewable energy sources and claiming that fusion energy would result in nuclear waste and nuclear weapons proliferation issues.[42]

A French association including about 700 anti-nuclear groups, Sortir du nucléaire (Get Out of Nuclear Energy), claimed that ITER was a hazard because scientists did not yet know how to manipulate the high-energy deuterium and tritium hydrogen isotopes used in the fusion process.[43]

Rebecca Harms, Green/EFA member of the European Parliament's Committee on Industry, Research and Energy, said: "In the next 50 years, nuclear fusion will neither tackle climate change nor guarantee the security of our energy supply." Arguing that the EU's energy research should be focused elsewhere, she said: "The Green/EFA group demands that these funds be spent instead on energy research that is relevant to the future. A major focus should now be put on renewable sources of energy." French Green party lawmaker Noël Mamère claims that more concrete efforts to fight present-day global warming will be neglected as a result of ITER: "This is not good news for the fight against the greenhouse effect because we're going to put ten billion euros towards a project that has a term of 30-50 years when we're not even sure it will be effective."[44]

Edited April 29, 2013 by Aladran

[Person012345]

Actually there is a better way to convert fusion released energy into electricity than using the inefficient boiler system used by fission reactor. You can send the plasma from the reaction through something called a "magnetohydrodynamic generator" (MHD generator) and get electricity out of it. Look up MHD generator in Wikipedia.

Doesn't wiki say that they're actually less efficient, but good by virtue that the hot exhaust gasses can then be used to boil water and drive a steam turbine, thus giving you double your money's worth?

[Person012345]

Some don't. The Polywell concept, if it is able to burn p-B11 fuel like its researchers claim it should, is inherently a direct conversion device. Meaning it takes energy away from the charged alphas by decelerating them in a magnetic field and inducing high-voltage current than you afterwards condition and pipe to wherever you want. Very efficient, considering 80% of the reaction's energy is contained in those alphas.

It's when you have to deal with neutron-producing fusion reactions when you have to make do with boiling water. And there's always the concept of magnetohydrodinamic conversion, though I must admit I haven't looked into that and might even be getting the name wrong. Something to do with building a "turbine" out of magnetic fields and working with plasmas as fluids.

Indeed and not all fossil fuel plants use steam turbines either afaik, but it's the most common method.

[Stochasty]

In 2005, Greenpeace International issued a press statement criticizing government funding of the ITER, believing the money should have been diverted to renewable energy sources and claiming that fusion energy would result in nuclear waste and nuclear weapons proliferation issues.[42]

A French association including about 700 anti-nuclear groups, Sortir du nucléaire (Get Out of Nuclear Energy), claimed that ITER was a hazard because scientists did not yet know how to manipulate the high-energy deuterium and tritium hydrogen isotopes used in the fusion process.[43]

Rebecca Harms, Green/EFA member of the European Parliament's Committee on Industry, Research and Energy, said: "In the next 50 years, nuclear fusion will neither tackle climate change nor guarantee the security of our energy supply." Arguing that the EU's energy research should be focused elsewhere, she said: "The Green/EFA group demands that these funds be spent instead on energy research that is relevant to the future. A major focus should now be put on renewable sources of energy." French Green party lawmaker Noël Mamère claims that more concrete efforts to fight present-day global warming will be neglected as a result of ITER: "This is not good news for the fight against the greenhouse effect because we're going to put ten billion euros towards a project that has a term of 30-50 years when we're not even sure it will be effective."[44]

These three paragraphs are nonsense - as to be expected from statements made by reactionary environmentalists with only the weakest understanding of the issues they're discussing.

That said, the part of the wiki article which talks about the technological challenges confronted by the Tokamak design is, if anything, understating the issue. Tokamak may, eventually, be a viable design, but it should not be getting the lion's share of the funding the way it is now.

[Relick]

In 2005, Greenpeace International issued a press statement criticizing government funding of the ITER, believing the money should have been diverted to renewable energy sources and claiming that fusion energy would result in nuclear waste and nuclear weapons proliferation issues.[42]

A French association including about 700 anti-nuclear groups, Sortir du nucléaire (Get Out of Nuclear Energy), claimed that ITER was a hazard because scientists did not yet know how to manipulate the high-energy deuterium and tritium hydrogen isotopes used in the fusion process.[43]

Rebecca Harms, Green/EFA member of the European Parliament's Committee on Industry, Research and Energy, said: "In the next 50 years, nuclear fusion will neither tackle climate change nor guarantee the security of our energy supply." Arguing that the EU's energy research should be focused elsewhere, she said: "The Green/EFA group demands that these funds be spent instead on energy research that is relevant to the future. A major focus should now be put on renewable sources of energy." French Green party lawmaker Noël Mamère claims that more concrete efforts to fight present-day global warming will be neglected as a result of ITER: "This is not good news for the fight against the greenhouse effect because we're going to put ten billion euros towards a project that has a term of 30-50 years when we're not even sure it will be effective."[44]

These three arguments have no basis whatsoever and you should not take heed. Nuclear waste is not created through fusion, we DO know how to use deuterium and tritium and nuclear bombs cannot possibly use fusion in its current state. Finally, it will combat global warming because (if it works), fusion makes no pollution allowing the trees to bring down CO2 levels.

The other three arguments you posted are valid though.

EDIT: WTF ninja'd.

[Nibb31]

So we're only a couple of decades away from sustainable fusion energy. Business as usual.

Indeed, fusion power has always been "in 20 years", even 50 years ago. It's a bit like a manned Mars missions or Lunar bases in that respect. Nobody really believes it any more. Add to the fact that it usually takes 10 to 20 years to build a new nuclear power plant, once the technology is available, so at best we are talking about the 2050's for operational fusion power.

And that is only if civilization can survive another 40 years on fossile fuels with 10 or 12 billion people while maintaining an economy capable of doing a decent level of scientific research and actually building that fusion power once we get there. I have the feeling the system will have broken down well before then.

Edited April 30, 2013 by Nibb31

[LewisTherin]

Indeed, fusion power has always been "in 20 years", even 50 years ago. It's a bit like a manned Mars missions or Lunar bases in that respect. Nobody really believes it any more. Add to the fact that it usually takes 10 to 20 years to build a new nuclear power plant, once the technology is available, so at best we are talking about the 2050's for operational fusion power.

The "always 20 years away" argument is a little tired. If you look at the actual developments made over time (in terms of temperatures, containment times, field strengths and ultimately Q factors) you'll see there's actually been significant progress to building a workable device over the last 50 odd years. If it turns out to be viable economically is a separate question, but the point of ITER is essentially to brute force a sustained fusion reaction to prove it can be done, while other more elegant methods may wind up being used in the future for actual power production.

And that is only if civilization can survive another 40 years on fossile fuels with 10 or 12 billion people while maintaining an economy capable of doing a decent level of scientific research and actually building that fusion power once we get there. I have the feeling the system will have broken down well before then.

This would be based on your scrying abilities I assume?

[Scotius]

Nibb31 is a pessimist And we do not have to trundle along only burning coal and oil for the next decades. Nuclear power plants are still completely viable, if unpopular option, and solar and wind power will contribute more and more to humanity's energy budget.

[bsalis]

Thorium fission works just fine though.

[Nibb31]

This would be based on your scrying abilities I assume?

Let's say that I don't have a blind faith in Humanity's ability to get together peacefully and fix all the World's economical, ecological, and demographic problems. Yeah call me a pessimist. I'd love to be proven wrong.

The future is unpredictable, and we are living in a time where the economical and demographical challenges are unprecedented. Many people put a blind faith in science and progress to solve all of our problems, because that's how it has always been. However, we can't simply look back at what we have accomplished over the last 200 years and assume that the party can last forever. 200 years is a blink of an eye when compared to the 200 000 years we've been around and the 4.5 billion years the World has existed. In those 200 years, we have changed the face of the Earth forever and burned most of our easily reachable resources. There are no lessons to be learnt from the past, because a situation like this has never existed before, and there is no reason to beleive that life is always going to be so easy.

We can increase productivity and efficiency through science and technology, but there are laws of diminishing returns at work here while our population growth and resource consumption are exponential. The first technological improvements (the agrarian revolution, then the industrial revolution) were cheap and easy, and the gains in productivity were massive. But the more productivity gains you squeeze out of the system, the harder and the more expensive it becomes, until you reach the point where the economical, social, or ecological cost of squeezing exceeds the relative productivity gain.

There is a race going on between technology opening up new horizons and our demand for growth. In a world of finite resources, it is going to take a lot of sustained effort for our productivity curves to keep up with the exponential demand curves. At some point in the future, those curves are going to intersect (if they haven't already), at which point we start losing the race. At some point, growth is going to have to slow down (it already is in the more developed countries), but our entire civilization is based on infinite growth, which is simply not possible.

If we want to survive, we are going to have to go through a serious rethinking of how the economy works, how we share wealth, and how we maintain a decent quality of life. I don't see how that sort of revolution can happen without a major conflict between those that want a better share of the wealth and resources and those that don't want to give up their share.

Edited April 30, 2013 by Nibb31

[LewisTherin]

Let's say that I don't have a blind faith in Humanity's ability to get together peacefully and fix all the World's economical, ecological, and demographic problems. Yeah call me a pessimist. I'd love to be proven wrong.

That was all very interesting, but predictions and opinions of broad socio-economic and political trends are essentially a moot point to what the thread is about - fusion, specifically through the use of tokamak type devices.

Based on the lessons that have been learned about how plasma physics and controlled fusion seem to work (a process that was far harder than initially thought - hence the parroted "perpetually 20 years away" line), in conjunction with the ability to model this physics, ITER was designed as a final test. As with every model, our understanding of what's going on with fusion needs validating conclusively, current experiments such as JET show that the fundamentals are strong, which is why the money was released to be spent on building ITER. Once it's finished in around a decade, the question is almost certainly going to change from "is it possible" to "is it economically viable" to use tokamak based fusion for large scale power generation.

[nyrath]

Doesn't wiki say that they're actually less efficient, but good by virtue that the hot exhaust gasses can then be used to boil water and drive a steam turbine, thus giving you double your money's worth?

Well, the next paragraph in the Wikipedia articles says that if you use fission or fusion instead of a coal fired plant they are more efficient than using a steam powered turbine.

https://en.wikipedia.org/wiki/MHD_generator#Generator_efficiency

[PIRATEONTHERUN]

And uranium is rare compared to deuterium. There is enough deuterium in Earth's sea water to power our civilisation for thousands of years. If we'd ever get to burning helium-3, it will be millions of years before we run out of power.

Sorry that I'm not very informed on this, but then why do people say there isn't enough helium for dirigibles to be viable?

Edit: I'm talking about how you said we have millions of years worth of helium-3.