What are disadvantages of nuclear fusion?

[Winter Man]

It's not impossible, or even that hard.

You're missing the bit where there's any point if we have fusion power, this being a fusion thread. Wind, tidal and solar are incredibly resource-intensive and have to be centralised. Distributed grids are what we need.

[rtxoff]

First of all, we solar people never said it is gonna be cheap. We are only saying it is possible to do. I do not care for the reasons why we will not do it. However fact is that it is possible. In 40 years when our grandchilds ask us if we really did not know it. What are we going to say them? I will say them i knew it, but the mainstream was blinded. You can not live in luxury overexploiting earth forever, at some point the bill will be presented. That bill will have to pay our childs and grandchilds. People here saying Fusion is the holy cow of energy production and it will solve world's problems, i say to you all that fusion is not going to change a thing in that matter. As long as people themselves won't change, nothing will happen. The problem needs to be fighted at the root. And the root my fellows are we all. You want to make the world a better place? Start by yourself. Ask yourself is it necessary to waste all the things you waste every day like food/energy/water/oil products and so on. I know that is hard, i am not doing it also but i won't lie to myself about that. Look at our sick society thinking of itself to be the masters of this world, i say we are just a small poo on this planet awaiting to be eaten up by our own stupidity. Most probably you will all hate me now for saying all this, i do not care somebody needs to say it. Just remember , saying you all did not know this won't count at the day X when you talk to your grandchildren.

[peadar1987]

You're missing the bit where there's any point if we have fusion power, this being a fusion thread. Wind, tidal and solar are incredibly resource-intensive and have to be centralised. Distributed grids are what we need.

And if we could get fusion to work, that would be fantastic. The point is, we can't make fusion for power generation work at the moment, and we don't know if we'll ever be able to get it to be commercially viable. We have the technology to build solar, wind, wave, geothermal, biomass, OTEC and tidal plants right now, or at least in the next 10 years if we put our minds to it. We also have huge potential to use low-grade heat sources, district heating schemes or bottoming cycles combined with increases in efficiency, for example.

In many ways, they're more suited to distributed generation than fusion is. Of course, fusion has the advantage of being pretty much insensitive to where you put the plant, but I'm guessing a fusion plant will probably benefit hugely from economies of scale. A 2GW plant will be far less expensive than 200 10MW plants, in all probability. I wouldn't say we'll ever see small rural communities with micro-fusion reactors powering them in the same way as microgeneration using current renewables can do.

[Winter Man]

And if we could get fusion to work, that would be fantastic. The point is, we can't make fusion for power generation work at the moment, and we don't know if we'll ever be able to get it to be commercially viable. We have the technology to build solar, wind, wave, geothermal, biomass, OTEC and tidal plants right now, or at least in the next 10 years if we put our minds to it. We also have huge potential to use low-grade heat sources, district heating schemes or bottoming cycles combined with increases in efficiency, for example.

In many ways, they're more suited to distributed generation than fusion is. Of course, fusion has the advantage of being pretty much insensitive to where you put the plant, but I'm guessing a fusion plant will probably benefit hugely from economies of scale. A 2GW plant will be far less expensive than 200 10MW plants, in all probability. I wouldn't say we'll ever see small rural communities with micro-fusion reactors powering them in the same way as microgeneration using current renewables can do.

This is a thread about fusion, it assumes it will work.

The scale argument doesn't take into account the fact that microgeneration with fossil fuels still goes on despite the cost. See: pretty much every vehicle. The incredible power density of fusion means it's automatically better suited to small, even portable applications.

The sheer square meterage required for solar or wind pretty much disqualifies its use in densely populated countries like the UK, or Hong Kong.

Edited May 22, 2014 by Winter Man

[Seret]

You're missing the bit where there's any point if we have fusion power, this being a fusion thread. Wind, tidal and solar are incredibly resource-intensive and have to be centralised. Distributed grids are what we need.

???

Wind, solar, and tidal are generally distributed. Certainly tidal stream, maybe not really big barrages. Much of the wind capacity is actually embedded, so it's not even monitored, it just shows up as a reduction in demand. It's the big thermal plants that are centralised. Stuff like coal, fission and when we get it fusion. Large hydro and to a lesser extent geothermal are about the only renewables that are big enough to centralise, and calling geothermal renewable is a bit dubious.

Decentralised power systems use solar, wind, small hydro, CHP gas turbines, biomass/EFW, and all the oddballs like digesters. You're not going to see small scale fusion plants.

[Dodgey]

Why are we forgetting fission. It has all of the benefits of fusion when compared to solar, wind ect and we can do it now. At least until we do get fusion.

[peadar1987]

This is a thread about fusion, it assumes it will work.

Just because the thread's about fusion doesn't mean it assumes it will work. The title is "what are the disadvantages of fusion". The main one of these is that it doesn't yet work, and it would be very strange not to discuss that.

The scale argument doesn't take into account the fact that microgeneration with fossil fuels still goes on despite the cost. See: pretty much every vehicle. The incredible power density of fusion means it's automatically better suited to small, even portable applications.

I'm not disputing the potential power density. I'm disputing the cost, robustness and complexity. We're pouring billions into fusion research at the moment, without even coming close to breaking even in terms of energy, let alone cost. And you're saying that we're not too far away from having remote rural communities powered by 100kW micro-fusion plants that cost less than a few solar panels or a diesel generator and are just as easy to maintain?

The sheer square meterage required for solar or wind pretty much disqualifies its use in densely populated countries like the UK, or Hong Kong.

-There are other countries apart from the UK and Hong Kong, which are very well-suited to such forms of generation (not to mention the fact that the biggest adopters of wind power are Germany and Denmark, which are hardly Outer Mongolia in terms of population density)

-The UK is surrounded by oceans, which could produce tidal, wave, and offshore wind with no major competition for space.

-Wind turbines have a pretty negligible footprint anyway.

[Winter Man]

An ITER-style tokamak costs billions, sure. Pretty much every other method costs a hundredth of the amount. Wind turbines' carbon footprint may be negligible, but what about all the other pollutants caused by their production? The point is, you're only comparing tokamaks as the be-all and end-all of fusion. As soon as you add dense plasma focus, polywells or 'concussive' fusion (for want of a better term), every argument against them falls apart.

[Seret]

-The UK is surrounded by oceans, which could produce tidal, wave, and offshore wind with no major competition for space.

Indeed. The UK has Europe's best tidal reserves (some of the best in the world, in fact) and offshore wind is booming. The biggest constraint on expansion for them is the availability of barge cranes for erecting them. The will and the money is there, generally speaking they're putting them up as fast as they can.

-Wind turbines have a pretty negligible footprint anyway.

Exactly, it's often possible to throw them up on industrial land with zero impact on the existing industry. Roof-mounted PV has a footprint of zero. Even large parks being erected on agricultural land allow grazing of small livestock like sheep on the same land, so space really isn't a biggy.

[Seret]

An ITER-style tokamak costs billions, sure. Pretty much every other method costs a hundredth of the amount.

The only other method in the serious running is laser inertial confinement. The NIF did indeed cost $1 billion to build, and it's just a test rig doing work that's more preliminary than ITER. So yes, it looks like fusion plants will cost billions whatever technology they use.

Wind turbines' carbon footprint may be negligible, but what about all the other pollutants caused by their production?

Carbon footprints are generally expressed in terms of CO_e, which takes account of all the other GHGs.

[Winter Man]

The only other method in the serious running is laser inertial confinement. The NIF did indeed cost $1 billion to build, and it's just a test rig doing work that's more preliminary than ITER. So yes, it looks like fusion plants will cost billions whatever technology they use.

http://www.generalfusion.com/

Another. Not billions, and not as 'preliminary' as ITER. Also, NIF was never supposed to be a power plant, it's a weapons research facility.

[peadar1987]

An ITER-style tokamak costs billions, sure. Pretty much every other method costs a hundredth of the amount. Wind turbines' carbon footprint may be negligible, but what about all the other pollutants caused by their production?

We were talking about a lack of space to put them up, I was just talking about the physical footprint.

The point is, you're only comparing tokamaks as the be-all and end-all of fusion. As soon as you add dense plasma focus, polywells or 'concussive' fusion (for want of a better term), every argument against them falls apart.

Apart from the argument that they still don't work. Tokamaks, ICF, sonoluminescence, all of these have been heralded as a way of unlimited, cheap, clean energy in the past. All of them have found that fusion is not as easy as that. When I see a fusion power plant that actually produces a sustained net energy output, then I'll be excited, genuinely I will be, but until then, the proven, already-existing-and-feeding-energy-into-the-grid renewable technologies like solar, wind, and marine renewables will always be better options.

[Seret]

http://www.generalfusion.com/

I can't check that site through my work network. If you're saying there's another form of fusion that's looking as promising as either magnetic or inertial confinement then that's news to me, but I'm no expert.

NIF was never supposed to be a power plant, it's a weapons research facility.

JET and ITER aren't designed to be power plants either. They're also just research facilities. That doesn't really change the fact that fusion does look like involving some pretty hefty hardware, which is hardly surprising considering the energies involved.

[Red Iron Crown]

Seret, here's the high level description of General Fusion's technique (not using quote tags so it's easier for posters to quote it):

"General Fusion’s Magnetized Target Fusion system uses a sphere, filled with molten lead-lithium that is pumped to form a vortex. On each pulse, magnetically-confined plasma is injected into the vortex. Around the sphere, an array of pistons impact and drive a pressure wave into the centre of the sphere, compressing the plasma to fusion conditions.

General Fusion’s Approach

Magnetized target fusion (MTF) is a hybrid between magnetic fusion and inertial confinement fusion. In MTF, a compact toroid, or donut-shaped magnetized plasma, is compressed mechanically by an imploding conductive shell, heating the plasma to fusion conditions.

MTF's advantages stem from its hybrid nature. MTF uses some magnetic field to confine the plasma, allowing for slower compression using mechanical systems. Magnetic fields in MTF are short-lived, avoiding complex plasma sustainment technologies.

By comparison, Inertial Confinement's fast compression requires high power lasers. Magnetic Confinement's long plasma life requires massive superconducting magnets, particle beams, and exotic materials."

[rtxoff]

Regarding the focus fusion: https://www.indiegogo.com/projects/focus-fusion-empowertheworld--3

I highly doubt that they will be able to get more energy out of the process then they need to make the plasma. To cite their own Website: "Focus Fusion works by driving over a million amps of current across a pair of cylindrical electrodes, creating a dense plasma where fusion reactions occur."

A million of amps are needed to create the reaction? For me that does not sound like it could work, however i could be very wrong and they are really up to something.

Maybe here on the forum are some scientists that could clear up things on this focus fusion?

[Winter Man]

*snip*

That's it in a nutshell. The lead/lithium mix is pretty good because the lead slows down the neutrons, then the lithium absorbs them and produces tritium for further reactions. The molten lead (now heated even more) goes through a heat exchanger to boil water and drive a turbine like every other 'conventional' plant.

[Winter Man]

Regarding the focus fusion: https://www.indiegogo.com/projects/focus-fusion-empowertheworld--3

I highly doubt that they will be able to get more energy out of the process then they need to make the plasma. To cite their own Website: "Focus Fusion works by driving over a million amps of current across a pair of cylindrical electrodes, creating a dense plasma where fusion reactions occur."

A million of amps are needed to create the reaction? For me that does not sound like it could work, however i could be very wrong and they are really up to something.

Maybe here on the forum are some scientists that could clear up things on this focus fusion?

Millions of amps over a fraction of a second.

[Red Iron Crown]

Amps aren't a good measure of power unless the voltage is known (and vice versa, of course).

[rtxoff]

Millions of amps over a fraction of a second.

Well i know that.

Amps aren't a good measure of power unless the voltage is known (and vice versa, of course).

I know that too.

I was hoping more of anybody coming up with some theoretical numbers. Because the homepage from this guys only explains some basics without any information for scientists to confirm. That makes me somehow skeptical. There have been already enough green energy companies trying to make money out of good willingness of people. So far this one could be also scam in my eyes.

[phoenix_ca]

Amps aren't a good measure of power unless the voltage is known (and vice versa, of course).

Exactly. Unless I'm mistaken, the strength of a magnetic field caused by an electric current is related to the amperage, not the voltage, of the current. Electrical engineers, time to give me a good talking to if I'm wrong.

I was hoping more of anybody coming up with some theoretical numbers. Because the homepage from this guys only explains some basics without any information for scientists to confirm. That makes me somehow skeptical. There have been already enough green energy companies trying to make money out of good willingness of people. So far this one could be also scam in my eyes.

That information is in the journal article they published, in a peer reviewed journal.

[Winter Man]

Exactly. Unless I'm mistaken, the strength of a magnetic field caused by an electric current is related to the amperage, not the voltage, of the current. Electrical engineers, time to give me a good talking to if I'm wrong.

You're quite right. Apparently the shots are supposed to be around 100kJ with a spark gap of about 10mm, although I think with the current anode design it varies. There's a way of working out the voltage and duration from that (I think you might need the pressure too), but I really can't be bothered with the effort for all it's worth. Running the machine at 200Hz they expect to get 25kJ surplus per shot, or 5MW from the little thing.

[Aghanim]

I prefer to run it at 50/60Hz and convert that to mains voltage already

EDIT: I'm wondering. If alt fusion tech like this succeeds to generate net energy first than ITER, what will happen to ITER? Do they will continue the research or not?

Edited May 23, 2014 by Aghanim

[phoenix_ca]

They've put too much money in to stop now. It'd be like building the LHC and then before switching it on say "meh, someone in some other country built a completely different collider, but hey, it's a collider too, we don't need this one".

[NERVAfan]

Solar power on Earth is a road to ruin, there simply isn't enough surface area available to power the entire planet.

Also someone calculated that a solar power plant big as the desert Sahara could produce enough energy for the whole planet. So the argument there is not enough surface area does not count too.

What about the fact that it's also the 'best case' scenario for a giant solar plant? It's the only equatorial desert, the best place for a solar plant, but it's still economically nonviable.

Actually, you don't need NEARLY as much as the Sahara desert.

Solar constant at Earth is ~1350 watts/square meter. Take off half for night, half for atmospheric absorption and the occasional cloudy day... that's about 340 watts/square meter... say 300. If the solar panels are 15% efficient, that's 45 watts per square meter... 45 megawatts per square kilometer... 45 terawatts for a million square kilometers. World use is more like 15 terawatts... and the Sahara is nearly 10 million sq km, comparable to the entire US. So it's (ideally) something like 333,000 sq km, more like 1/30 of the Sahara or about half of Texas.

The more significant problem is that it would be incredibly difficult to build and maintain 333,000 sq km of solar panels, and the places they could be put with relatively little environmental harm (like the Sahara desert) are not very close to large populations.

(And the Sahara is not equatorial. It's more like 30 north latitude.)

The only other method in the serious running is laser inertial confinement. The NIF did indeed cost $1 billion to build, and it's just a test rig doing work that's more preliminary than ITER. So yes, it looks like fusion plants will cost billions whatever technology they use.

What about polywells (electrostatic confinement)? I think there's a group working on them funded by the US Navy. They're supposed to be workable on a small scale (if they work at all), like a few meters wide.

Also, I believe Lockheed Martin Skunk Works is working on some fusion thing... supposed to have a prototype by 2017...

[Aghanim]

Is it just me or Lockheed high Q fusion is just a vaporware?

And as Seret says, he meant that the fusion technologies that are currently in serious research. Alt fusion techs like DPF, polywell, magnetic mirror, MTF, Z pinch, doesn't receive that much funding as mainline fusion like tokamak and ICF

Proof: The DPF crowdfunding

Edited May 23, 2014 by Aghanim