[alancalverd (OP)]

Under the headline "Pollution-free electricity moves a step closer to reality thanks to British scientific breakthrough", Sky News today revealed that the UKAEA has developed a new exhaust pipe for a tokamak:

"It's a pivotal development for the UK's plan to put a fusion power plant on the grid by the early 2040s - and for bringing low-carbon energy from fusion to the world."

Fusion power was "only 5 years away" when ZETA was unveiled in 1957, and has steadily retreated at a rate of around 2.8 months per year ever since.

Would anyone care to calculate when we will see the first actual fusion kWh on the grid, and how long it will take to repay the R&D costs of getting there? 

Edison's light bulb patent was granted in 1879 and by 1882 ConEd was supplying mains power to Manhattan.

What has gone wrong?

[evan_au]

Fusion is already the primary power source on the planet.
- And it has been since before the first patent was filed on hydrogen fusion.
- Thanks to the Sun

[CliffordK]

Fusion Energy was demonstrated in 1952...  a lot of it!!!

The problem has always been a combination of starting the reaction and containing it.

It appears as if several test reactors have achieved fusion, but not energy parity.  But, ITER should be coming on line with positive energy production. 

Then several more similar plants will be built  But, it is unclear how long until we will have viable commercial devices.

[Petrochemicals]

Have you not got your robot maid on your moon house yet Alan? You must have missed the memo

Problem is that the fusion of hydrogen has efficiency problems relating to the Columb threshold I believe, more power in than out. I think the crux of it is the sun is a huge gravitational body that somehow violates  the conservation of energy when viewed from our understanding. I do not believe we are looking in the right place. Einstein said to repeat the same experiment repeatedly in the hope of getting different result is the definition of insanity. We will not achieve fusion until we master gravity. It does not take much energy to put something into orbit, but for some inexplicable reason we cannot achieve that either.

[Bored chemist]

Problem is that the fusion of hydrogen has efficiency problems relating to the Columb threshold I believe, more power in than out.

No, it doesn't. Consider the H bomb.

. I think the crux of it is the sun is a huge gravitational body that somehow violates  the conservation of energy when viewed from our understanding.

No, it doesn't. Consider the H bomb.

We will not achieve fusion until we master gravity.

No; see above.

Why do you post such obvious tosh?

[Bored chemist]

It does not take much energy to put something into orbit, but for some inexplicable reason we cannot achieve that either.

We do that quite a lot.
Why do you post such obvious tosh?

[CliffordK]

One of the problems with fusion is that we are nowhere near doing simple 4¹H ==> ⁴He, however you balance that equation.

So we're using various heavy isotopes:

²H + ³H ==> ⁴He + neutron

Unfortunately, I don't believe we have an easily accessible source of heavy hydrogen isotopes outside of nuclear reactors.

So, in the near future, there isn't much chance this will replace nuclear fission.

Perhaps one could add standard ¹H to the plasma stream and it will occasionally absorb the neutrons released.

[Bored chemist]

Unfortunately, I don't believe we have an easily accessible source of heavy hydrogen isotopes outside of nuclear reactors.

I believe they did that calculation a long time ago, and while separating heavy hydrogen is not trivial, it is viable.
Otherwise, they wouldn't have bothered.

[alancalverd (OP)]

This story of Norsk Hydro at Rjukan is worth a read for anyone interested in zero-carbon electricity, deuterium, cross-country skiing, glider assault, and high adventure that seriously impacted the Second World War.

https://weaponsandwarfare.com/2016/04/16/norwegian-heavy-water-raids

[CliffordK]

Unfortunately, I don't believe we have an easily accessible source of heavy hydrogen isotopes outside of nuclear reactors.

I believe they did that calculation a long time ago, and while separating heavy hydrogen is not trivial, it is viable.
Otherwise, they wouldn't have bothered.

It has been discussed off and on.

Deuterium has an abundance of 0.01%, but is apparently relatively easy to isolate. 

Tritium, on the other hand, has much lower abundance due to its relatively short halflife. 

It is produced in nuclear reactors using ⁶Li, which is also the least common lithium isotope, but perhaps the battery industry could provide needed feedstock.

[Bored chemist]

Tritium is rare, but irrelevant to power production.
You don't need tritium to do fusion.

It is easier to fuse so some experiments (and bombs) use it.

If you have a working D+D fusion reactor then you have an abundant source of neutrons to produce T if you really want it.

[evan_au]

(Tritium) is easier to fuse ....
If you have a working D+D fusion reactor then you have an abundant source of neutrons to produce T if you really want it

At present, we don't have any working controlled fusion reactor.

The graph here: https://en.wikipedia.org/wiki/Fusion_power#Lawson_criterion
...suggests that at a somewhat practical temperature of around 100 Million K, D+T fusion runs about 100 times faster than D+D fusion
- D+T has the drawback that neutron radiation does make the reactor housing radioactive,
- but if we can get any controlled Hydrogen fusion to work, D+T will produce about 10-100x the power of a D-D reactor (all other things being equal).

[Bored chemist]

At present, we don't have any working controlled fusion reactor.

High school kids working in garages have working controlled fusion reactors.
https://fusor.net

[wolfekeeper]

Making sustained fusion work is reasonably easy, school children have done it before. Making fusion work where more excess energy comes out than goes in is a bit harder, but has been done. Making fusion work where the excess energy coming out is sufficient and of a form suitable for running the reaction is harder still. To make fusion work as a practical power source, you have to be able to do all that, as well as being able to run the reaction continuously, it must produce enough energy to pay for the construction and operation, and that's even harder.

Frankly, if people had just taken the same amount of money they've spent on this, and invested it in renewables instead, we would quite possibly already be carbon neutral, since it would have pushed the state of the art further along.

[Petrochemicals]

This story of Norsk Hydro at Rjukan is worth a read for anyone interested in zero-carbon electricity, deuterium, cross-country skiing, glider assault, and high adventure that seriously impacted the Second World War.

https://weaponsandwarfare.com/2016/04/16/norwegian-heavy-water-raids

Vast over reaction. The scientists where on a go slow, the  Reich disposed of the uranium for shells due to being told that it was impractical in the next 30 years, the experimental bomb devices where the size of houses. Quite a few Scandinavian civvies died in the collateral damage, plus the heavy water was easily replaced and the damage repaired.

Making sustained fusion work is reasonably easy, school children have done it before. Making fusion work where more excess energy comes out than goes in is a bit harder, but has been done. Making fusion work where the excess energy coming out is sufficient and of a form suitable for running the reaction is harder still. To make fusion work as a practical power source, you have to be able to do all that, as well as being able to run the reaction continuously, it must produce enough energy to pay for the construction and operation, and that's even harder.

Source please.