Fusion Confusion

I am a member of the Dispatch community, and its morning newsletter had a helpful article on the fusion discovery. It is remarkable, but it doesn't mean what we think it means (to quote Inigo Montoya from The Princess Bride).  I will put a few paragraphs here, since I really can't copy and paste the whole article.  The rest of this post is from The Morning Dispatch, designated by using a different font.

Scientists had previously lit the fusion match—to much fanfare each time—but they played a little fast and loose on what had actually been accomplished, as Charles Seife noted this week. Livermore, for example, announced in 2014 it had achieved net energy gain. “This was nothing more than an accounting trick,” Seife—a science journalist and author of Sun in a Bottle: The Strange History of Fusion and the Science of Wishful Thinking—wrote. “Instead of comparing the fusion energy produced with the energy of the incoming laser beams, NIF scientists had compared it with the small fraction of the laser-beam energy that struck the target chamber, got converted into X-rays that shined onto the target, and was eventually absorbed by the fuel—which is to say, roughly 1 percent of the total. Fiddling with the denominator turned a 99 percent failure into a 100 percent victory.”

 

That’s not what happened this month, as LLNL’s latest experiment reportedly met the scientific definition of ignition. The laser beams sent 2.05 megajoules of energy, and neutrons produced by the fusion reaction returned 3.15 megajoules, enough to boil a couple gallons of water. “In all the previous experiments, you always had to put more energy in,” Karl Krushelnick, a professor in the University of Michigan’s Nuclear Engineering and Radiological Sciences department, told The Dispatch. “This demonstrates this could actually be a real source of energy if we can harness it and do the engineering to make the reactor work.”

 

That’s a big if. Scientists may have cleared a major physics hurdle, but fiendishly difficult engineering problems remain before fusion is a plausible—let alone cost-effective—power source. Scientists will need to achieve much higher energy return levels, which means more powerful and efficient lasers and ones capable of firing thousands of shots per day instead of just one. Smoother, stronger, and cheaper fuel pellets will also improve the process. Plus, physicists and engineers will need to build efficient ways to capture the resulting energy and transfer it to electrical grids—and all these systems must be simple and resilient enough that maintenance costs don’t overwhelm commercial profits.