Fusion?

I saw that article - it was very interesting.

 

Like synthetic gasoline, it will probably cost more that wind or solar for many years to come.

Industrializing the process will be very expensive and will require new technological processes not yet developed.

 

I understood it the same way as Mendel - a net energy gain from the reaction - if it works out a dynamic game changer in the energy game where currently you always put in more resources to obtain less energy.

 

it's a start. how long will it take to make it commercially effective, if ever, is anynes guess.
but better than no start

 

This guy had it figured out 50+ years ago but whatever

 

Source: Physics - Fusion Turns Up the Heat

A nice technical summary. What I like is feeding the lasers via the ends. The heat and by products have most of a sphere to absorb everything.

Bob Wilson

 

That piece exhibits some poor journalism. All its videos and the illustration are strictly about the Tokamak machines: Joint European Torus in the UK, and ITER in France, which use magnetic confinement of a plasma in a large torus.

Today's announcement was about the National Ignition Facility (NIF) in the U.S., using the very different method of laser inertial confinement, compressing a tiny fuel pellet. While described near the article's end, it is not illustrated.

I find it wonderful that both methods have made great progress recently. The UK machine set a new performance record a year ago: An artificial sun briefly blazed under the English countryside.

The UK machine seems to still hold the record for the most energy produced in a run, 59 MJ over 5 seconds, but it was still only 1/3rd the energy put in to the reaction, so didn't break even. This new NIF produced about 3 MJ output for 2 MJ input, finally beating breakeven by one measure.

Though by another measure, that 2 MJ is just the energy of the laser light that hit the target pellet carrier and compressed the fuel. It took more than 400 MJ to charge the lasers.

Also, a caveat on the claims that fusion energy will be "clean". In reality, it provides energy by spewing out neutrons and other particles, which are absorbed and converted to heat in the walls of the containment vessel, then will make steam to drive turbines. The good news is that the fusion reaction's exhaust products are not radioactive, a big improvement over today's fission reactors where the reaction product is very radioactively hot.

The bad news is that the neutron irradiation of the containment vessel will make it radioactive, and therefore a future waste disposal problem. This shouldn't be nearly as bad as today's fission waste, but it will still be a problem, more so than most news articles admit.

 

A fusion reaction is nothing new on Earth, the problem with developing fusion reactors to produce electricity is the HEAT generated in the process. This is one of those times of people getting excited over something that has been done before but still isn’t feasible with our current technology.

 

A fusion reaction emitting a bit more energy than was needed to instigate it is something new on Earth though, so even if it's still just a step along the way, it's a kind of exciting one.

Engineering challenges include not just the HEAT but also the pesky neutrons, as fuzzy1 commented. If I remember right, beyond making the containment vessel walls radioactive, it can also embrittle some materials.

 

“Nuclear” fusion isn’t the same as the “nuclear” energy you are used to. Two hydrogen atoms are combined resulting in helium and heat; where in fission, radioactive materials (usually uranium, even plutonium) are split apart releasing the energy (and much less than in the fusion process).
Most people confuse the fusion process with the Hydrogen Bomb that used a fission reaction to ignite the fusion process. What occurred in this “breakthrough” was using lasers to ignite the process. The embrittlement that you are remembering is a result of the extremely high temperatures that are generated by a fusion reaction (reaction here is not what most people think of when they see the word “reaction” ie: “nuclear FISSION reaction that releases energy and elements that are radioactive”), it is the result (reaction) of combining two or more elements. And it has been done before on earth. To understand it you have to understand particle physics, and physics in general (something not taught in the US public school system anymore).

 

I agree with @fuzzy1 assessment that magnetic confinement is a bit further along. And that we are nowhere near the coda. But those gigalasers still seem kinda cool.

 

My understanding has always been that the embrittlement is from the neutrons themselves, as Chapman described, not from the high temperatures. The pressure vessels of fission reactors suffer the same type of problem, even when no hotter than pressurized boiling water, typically 290ºC.

See: https://en.wikipedia.org/wiki/Neutron_embrittlement

 

Nuclear fission produced electricity on a kW scale just 9 years after the first controlled sustained reaction, or 6 years after the first uncontrolled explosion as a weapon. Utility scale electricity followed just 3 years later in the Soviet Union, or powering the town of Arco Idaho 4 years later.

The first fusion chain reaction was uncontrolled, a record-setting bomb. 70 years later, we've been able to create a controlled reaction only comparatively recently, sustain it multiple (5) seconds only very recently, and reach energy break-even (by a very loose definition) only last week.

No existing fusion machine, not even the under-construction ITER, can generate electricity. I have no idea when fusion-powered electricity will be demonstrated, let alone delivered.

 

In order to use it to provide steam to drive a turbine and a electrical generator, we first have to actually control the process (ironically, humanity faced the same problem when trying to harness steam power from wood). The additional problem we face with fusion is the extreme heat generated from the fusion of the two elements, which is much greater than the fission of two elements. Plus the extreme energy required to force the two elements together (fusion).
Don’t get me wrong, the problems are not insurmountable, and fusion power is much better than fission for the purpose. My point is everyone is getting excited over a very tiny step in the process, and acting like it’s never been done before.

 

While I confess that I had those classes in a private high school and a private college, I'm pretty sure many people emerge from public high schools and universities understanding them even better than I do (not a really high bar).

The stuff I remember about neutron embrittlement jibes with what fuzzy1 remembers.

Well, that's the key in the current news cycle. Forcing the two together (with extreme energy) and fusing them is the part that's been done before. Getting more energy back out than you spent forcing them together, that's the new thing.

And it's a pretty encouraging new thing. Without being able to do that it, fusion wouldn't be nearly as interesting.

 

In the distant future there will (may?) be a 1000 megawatt fusion reactor for electrical generation. Typical size of large fossil-fueled units now. It would obtain 1000 megawatts by fusing 100 kg of deuterium (2H isotope) with 150 kg of tritium (3H isotope). Some megawatts will be required to 'put the squeeze on' that DT, I can't guess that.

100 kg of deuterium is contained in a bit less than 18 million liters of water. Seawater or 'fresh'; doesn't matter. Seawater is mentioned in links above so maybe somebody has reason to suppose that is the better source. It sets my mind a thinkin. If seawater is already being desalinated, its deuterium will be concentrated on the 'reject water side'. So, maybe that's a play. There are several ways to extract deuterium, each requires some energy, and I do hope somebody has worked those out.

150 kg of tritium is a different matter. It is a radioactive isotope with 12 (ish) year half-life. So you must make your own. It can be 'conveniently' (so I read) produced by neutron irradiation of lithium. Not all lithium production needs to be used for EV transportation right? Or, for more fun, take end-of-life lithium batteries, hit them with neutrons (if you got 'em) and capture tritium as it diffuses away. Anyway, 150 kg of tritium must be sourced for each 1000 megawatts this fusion reactor will supply.

But let optimism flow. Squeeze is made with magnets or lasers. Your device is generating much heat! Transfer that heat with a working fluid (probably water) to turbine generators, and many megawatts become yours to sell. And to continue to sell, as long as you supply deuterium and tritium.

You (not you reading, exactly) have made a new type of thermal power plant, just as dependent on working-fluid (water) supply as the fossil-based ones, that are widely seen as troublesome throughout the fossil supply chain. It 'boils down' to water supply. Such cannot be built where water supplies are already contested for agriculture, industry, direct human use, or (dare I say it) biodiversity. A persistently wet place is needed,

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So, yeah, late this century or early next, make these fusion miracles as well as your granchildren can. Put them in places lacking water-supply conflicts, and string long electrical-supply lines to population (energy-demand) centers where water-supply conflicts already exist. They will be competing for big-money investors against wind and solar, which already perform.

 

Are these units missing a time dimension? 1000 megawatt ... ⋅seconds? ⋅hours?

I am here making a brazen play to avoid doing the math myself.