
A faster, cheaper path to fusion energy - gmiller123456
https://phys.org/news/2018-11-faster-cheaper-path-fusion-energy.html
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noetic_techy
I've seen the MIT lecture that presented this. Here are the main hurdles:

1) Estimated $40 billion USD need to build a test reactor.

2) Not enough FLiBe fluid (Low-Z fluid) on the planet for the reaction
chamber. Would need large scale manufacturing.

Source: [https://youtu.be/KkpqA8yG9T4](https://youtu.be/KkpqA8yG9T4)

~~~
baking
The large scale project using low temperature superconductors is ITER,
initially proposed at $5 billion and currently estimated at $20 billion for a
scientific test reactor.

The MIT ARC design is half the size using high temperature superconductors and
should be in the $1-2 billion range for a full-scale 500MW pilot production
fusion reactor.

What is currently being proposed (the subject of the papers being delivered
tomorrow) and funded with private money is a $200-250 million SPARC (Smallest
Possible ARC) that is half the size again of the full-size ARC.

So yeah, you are off by a factor of 160.

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pontifier
I think I could build my prototype fusion device for under $1M

Maybe if I said it would cost more to build, people would think it more likely
to work.

~~~
FiatLuxDave
That may be possible. I built my fusion prototype for about $600k in 1990s
dollars.

Being more expensive doesn't make people think it is more likely to work. The
easiest way to make people think your design will work is to take an existing
design with known parameters and make it 'better'. Unfortunately, 'better'
often means bigger and more expensive, which is how we get to projects like
ITER. SPARC is a version of a compact tokamak using advances in high
temperature superconductors - thus, 'better'.

A different way is to propose something completely different than what has
been done before. Then, if it is cheap enough, people may be willing to take a
chance on it. This is what I did. However, it needs to be different enough to
not be easily dismissable as having the same problems as an earlier design.
For example, if you are doing a mirror design, you better have a good answer
for fixing the ends.

One thing that often gets overlooked when talking about cheaper fusion designs
is speed. Big projects like ITER take a long time to build, and then a lot of
experiments get done on them, taking more years, because you need to get your
money's worth from them. Smaller designs get the knowledge gains out of the
design much faster. Robert Hirsch has been trying to bring this to our
collective attention ever since he converted from a tokamak proponent to
opponent decades ago.

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baking
I think this talk
([https://youtu.be/L0KuAx1COEk](https://youtu.be/L0KuAx1COEk)) makes a pretty
good case for why a project of the scale of SPARC makes sense from an
engineering standpoint.

~~~
pontifier
Very interesting video...

My answers to the questions in the video are:

Fuel: D-D

Temperature target: 15kev

Confinement: hopefully approaching ideal at small ion counts. (penning traps
are very good at trapping particles for long periods of time)

Instabilities: unknown but probable at high ion counts. I know there will be
challenges to solve, but hopefully they are not fatal problems.

I believe the first prototype could achieve Q>1

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opwieurposiu
This talk explains the advantages of the new YBCO tape superconductors in a
lot more detail.

[https://youtu.be/KkpqA8yG9T4](https://youtu.be/KkpqA8yG9T4)

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threeseed
What people forget about massive projects like ITER is that it is almost
irrelevant whether it works or not. It is a highly technical construction
project involving dozens of countries mostly in the EU. So the return on
investment comes not just directly from increased economic activity but also
from levelling up the skill of member companies.

And so if SPARC does end up working you will have member companies who are
well placed to capitalise on it.

~~~
fvdessen
How many SpaceX could we have for one ITER ?

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unmole
How many SpaceX could we have without a NASA and a Roscosmos?

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pfdietz
Another potential problem with this idea is enhanced corrosion by the molten
salt flowing in the strong magnetic field.

The conductivity of the molten salt is low, so JxB forces will be low. But
this means there will be a voltage drop across the salt as it flows in the
magnetic field. On one side of that circuit, there will be energy available to
oxidize the metal past which the salt is flowing.

Now, from what I see, they're keeping the flow rate low enough that they don't
produce elemental fluorine on that side. But there's still a voltage there,
and the corrosive behavior of FLiBe hasn't been tested, as far as I know, in
systems with that extra bit of energy available (nor with that extra energy +
strong neutron radiation).

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heimdall
From the comments:

> _ITER was designed before the newest generations of superconductors were
> available. ITER is now succumbing to the escalation of commitment that sunk-
> costs engender. SPARK [sic] has the advantage of an agile development model
> and new materials and technology that combined, dramatically shortens the
> path to breakeven and the reduction in costs to do so._

Just imagine where we'd be if fusion science were given equal footing with
other investment endeavors.

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tasty_freeze
The US spends more than $850B every single year on the military. If a tiny
fraction of that was spent in gaining complete energy independence, it would
pay for itself in that we wouldn't need as big of a military.

~~~
eloff
Not to get too far off track, but I always thought in a magical alternate
universe in which I could make US policy, I'd modernize the nuclear Arsenal
and ditch spending on everything else in the military. Couldn't play global
policeman anymore, but nobody seems grateful to the US for that anyway. And
let's face it, if it really came to a confrontation with another world power,
it will end in nuclear war even if it doesn't start out like that. It seems to
me that everyone is still fighting the last war. Why do you need conventional
forces in a nuclear world?

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pdonis
_> Why do you need conventional forces in a nuclear world?_

Because you don't want your only options for dealing with other countries to
be "do nothing" and "start a nuclear war".

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eloff
What's wrong with do nothing? What business is of the US what happens in the
rest of the world? I mean as much as people criticize the role they played, I
think the world is better off for it. But it's a thankless job. Turning inward
and leaving the world to go as it will is a valid strategy. Perhaps even the
best one for the US. Nukes are good enough for self defense.

~~~
mijamo
All the US intervention are based on pure self interest, nothing to do with
policing the world. If anything most of the world would have been better off
without US interventions, particularly latin america and middle east!

Now let's say you don't have conventional weapons.

China invades all South East Asia progressively. Would you nuke them? Russia
invades Eastern Europe. Would you nuke them? If yes why hasn't the US nuked
Russia yet?

Then all your allies suddenly switch side after being overthrown by dictators
who are in favor of your enemies. Would you nuke them?

Another one: you are terrorists associations preparing attacks against you in
camps all across middle east. Who do you nuke to defend yourself?

Conventional weapons are actually the only useful tools nowadays, because war
is much more sneaky than it used to be, and it is much more about fighting for
influence than really invading countries or defending you territory.

~~~
eloff
Basically no to all of the above. One can question the wisdom of not standing
up to aggressive nation states attacking and conquering other states - and
doing nothing. Let's say the US had invented the bomb earlier and was using
this strategy during the rise of Nazi Germany. Basically the plan would be to
leave Japan, Russia, Germany, Italy unchecked as they conquered state after
state until the whole rest of the world fell under horrifying authoritarian
rule. Until one eventually comes for the US and both commit suicide. It seems
a much worse scenario than the already horrifying one we had.

On the other hand let's say all had the bomb but are reluctant to use it. The
nation's fight it out with conventional weaponry until the axis powers,
realizing they have lost and with invasion in progress finally feel they have
no other choice and commit mutually assured destruction. I think it would be
hard to claim that wouldn't have happened given the temperament of some of
their leaders. Perhaps in this case the allies would have showed restraint and
not invaded to end the war - perhaps they would have been willing to negotiate
terms.

I think basically my idea is a terrible one. But I also think the world war II
scenario would end in nuclear exchange - the only way to avoid that is not
push any power to the point of last resort, and negotiate an unsatisfying
agreement that leaves the aggressors in power, no matter what horrible things
they do. Would all have shown such restraint, would cooler heads have
prevailed amid the terrible atrocities of total war? I'm not particularly
optimistic of the chances.

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naasking
Alternative approaches to fusion need to be explored, like focus fusion,
polywell, ICF, etc. ITER and the like are great for physics and for the
engineering challenges it presents that will likely be applicable elsewhere,
but the complexity means it probably won't be viable as a generator for
decades to come.

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xutopia
Can someone explain to me why fusion energy isn't violating the laws of
physics?

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cookingrobot
I used to be confused about how both fission and fusion can release energy.

It turns out elements lighter than Iron release energy when they combine
(fusion), and elements heavier than Iron release it when they split (fission).
So for any element, it only releases energy as it gets closer to becoming
Iron.
[https://en.wikipedia.org/wiki/Iron_peak](https://en.wikipedia.org/wiki/Iron_peak)

~~~
Roboprog
There’s a certain amount of irony (iron-y?) that heavy fissionable materials
are formed when fusion stalls: the core of a large star is turned into iron,
fusion “goes out”, then the star collapses and goes supernova. Heavier
elements are formed in the “bounce” when the outer layers of the star crush
down the suddenly cold(er) core, converting the kinetic energy into reactions
that absorb energy by fusing heavy elements.

Or something along that line, anyway.

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zyxzevn
I think there is still the problem that very strong magnetic fields are
causing "magnetic breaking".

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newnewpdro
> A faster, cheaper path to fusion energy

Yeah, solar panels.

