Friday, December 11, 2015

Nuclear Fusion? Maybe, maybe ...

We're trying to make stars on Earth.  Luckily for everyone's weight, there isn't enough mass on Earth to make a star the usual way, via gravity.  Instead, we're trying to initiate fusion in a controlled manner, the true holy grail of clean energy for many decades.  Fuel for fusion is abundant and safe and the waste byproducts require far less special care than their fission counterparts.  The standard joke about fusion is that it's always 50 years away.  While true in some sense, people who actually work on fusion would tell you that it's been $80 billion away for decades.  I always like to show this graphic made by Geoff Olynyk when "fusion will always be decades away" rears its ugly head.


Way back in 1976, these were the projections for when we might have fusion given various levels of funding.  Even then, they had the humor to label the projected 1978 level of funding "fusion never."  While I tend to take graphs like this with a grain of salt (predicting the future is hard), the absolutely dreadful level of actual funding is far more astonishing to me.  Do you know how little money $80 billion spread over 15-30 years is compared to a decades-long Cold War?

Hyperbole aside, I let fusion lapse from my attention a bit.  From the "NUCLEAR BAD!!!" camp to the "That's science fiction" to the blank stares, it just didn't seem like the collective fortitude required to attain fusion was there.  I also saw that ITER, the main tokamak project in the world right now, was having difficulties, technical, economic and political.

Then, along came Weldenstein 7-X (W 7-X).  Not being a nuclear engineer nor having quite the time to delve fully into all the tokamak alternatives, I didn't even know what a stellerator was a few months ago.  Glossing over many details, I think Thomas Klinger, the Scientific Director of W 7-X, put it best.  "They are both terrible beasts.  Our's [stellerator] is a beast to build; your's [tokamak] is a beast to operate."

A tokamak is basically a giant magnetic donut.  Intense magnetic fields confine a plasma hot enough to initiate nuclear fusion.  The big problem: the plasma wants to radiate outwards from the center, forcing tokamak designers to jump through all kinds of hoops to keep it on its circular path.  A stellerator, on the other hand, is ... is ... well ... hard to describe.  Here's a picture.


You can go to ScienceMag, where I got this picture from, for further details.  The idea is to fight the outward radiation that tokamaks contend with by making the plasma twist around as it "orbits."  In my completely non-expert understanding, just when the plasma wants to go off course, you twist the course so it comes back in, which results in the weird, twisty thing pictured above.  W 7-X just turned on for the first time Thursday (Dec 10).  It did everything it was supposed to do and the project participants are pleased as punch.  Even if W 7-X performs exactly as designed for the remainder of the project's duration, it still won't generate commercial levels of energy.  However, it is an important research platform and demonstration of fusion's potential as a clean energy source.

I really hope some form of fusion finally makes its way to commercial usage eventually.  We have enough fuel on Earth to produce energy at current levels for millions of years and that fuel (heavy water and lithium) is in places we don't have to fight wars to secure.   If this really works and does so soon enough, perhaps the inaction at the Paris climate talks won't matter.

2 comments:

  1. Tri Alpha Energy to the rescue. Local SoCal pride (or mushroom cloud)!
    http://phys.org/news/2015-08-tri-alpha-energy-reportedly-important.html

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  2. yeah, that was pretty exciting. haven't heard a peep about it since though. that's private vs public for you, i guess.

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