Practical Fusion Only 30 – 50 Years Away?

Since the 1970’s, practical fusion has been 30 years away and that is because at best we can only dimly see what will be happening even 10 years from now. There has now been a breakthrough in fusion with laser implosion. In an instant, a pulse of focussed lasers blasted the outer shell off a million dollar pellet and imploded a core of probably lithium deuteride. Deuterium and tritium atoms combined to form helium and a vast flux of energy was released. For the first time energy out exceeded energy in, a triumph of science, opining the possibility of infinite energy for mankind.

However, the experiment was never designed as a continuous source of power and it is difficult to imaging how this could ever be scaled from one pellet to multiple pellets of fusion fuel per day, producing large amounts of energy that would not vaporize the surrounding lasers. That engineering, probably with a different way to confine and heat plasma, will take another 30 to 50 years. But that’s only a guess.

Meanwhile, don’t let the promise of fusion stop us from developing more safe nuclear energy.

Fusion works, but uses a supernova budget to make a mini sun for a fraction of a second

By Jo Nova

Eruption of a solar flare and a lunar transit

Fusion reactors will one day be the ultimate in “free energy”, but judging by the latest news of holy grail moments, it won’t be soon. The bonanza of energy that everyone wants was never going to come by catching photons from the sun with a million square kilometer PV net,  but from recreating the source of those photons here on Earth. It’s the energy released if we can smack two atoms together and make them fuse which requires extreme temperatures and pressures (a bit like the sun) and do it efficiently, reliably, and millions of times a day.

In the latest nuclear news round, the mini sun experiment at the Lawrence Livermore National Laboratory California gave back slightly more energy than was directly put in, which seems very exciting, but systemic total costs and energy used to “make this moment” happen are in a Supernova category all by themselves.

UPDATE: Just after publishing this blog post, news came out of a newer experiment just ten days ago:

The US’s National Ignition Facility (NIF) has announced it successfully used a 192-beam laser to turn a tiny amount of hydrogen into enough energy to power about 15 – 20 kettles. This means that – for the first time – scientists were able to generate more power than the lasers put in to the experiment. — BBC

On Dec. 5, 2022, the National Ignition Facility shot a pellet of fuel with 2 million joules of laser energy – about the amount of power it takes to run a hair dryer for 15 minutes – all contained within a few billionths of a second. This triggered a fusion reaction that released 3 million joules. That is a gain of about 1.5, smashing the previous record of a gain of 0.7 achieved by the facility in August 2021.    — The Conversation

The newer numbers are slightly better than the ones released last week. This is the same lab. The energy gain appears to have improved from 20% to 50%.

Art Berman gives us a summary of Javier Blas’s description on the fusion “breakthrough”.

1. Experiment lasted a fraction of a second.

2. It released 2.5 MJ [now 3.15 MJ] vs 2.1 MJ of energy [in]. But the lasers consume ~330 MJ to charge.

3. Lasers can only fire once a day.

David Whitehouse, NetZeroWatch is similarly skeptical:

 It’s become something of a bad joke amongst the science community that fusion is always decades away. 

The announcement itself is a puzzle and had the feeling of being some much needed good news to announce. In reality although the experiments referred to took place a few months ago the “breakthrough” results were reported a year ago with the major advance being published in the Journal Nature in 2014. By one analysis 2.05 MJ of energy pumped into the pellet produced 3.15 MJ of energy. This does not include the 322 MJ needed to run the 192 lasers. So the story wasn’t a real breakthrough, just an advance. In any commercial development of this laser technique millions of fuel pellets would be needed for each reactor a year. At present they are tailor-made and cost almost $1 million each.

A few magnitudes of inefficiencies to go:

Javier Blas, the Energy and commodities columnist at Bloomberg, puts some details on just how many more years work may be required here

If confirmed, the breakthrough is quite important, putting the world into the realms of “fusion ignition”, and perhaps in the future into a sustained and controlled fusion reaction. Sustained is a key word there. The current experiment lasted a fraction of a second. 

There a few extra caveats. [Like] what net energy means? The lasers used by the Lawrence Livermore laboratory are extremely inefficient, so although the experiment produced net energy compared to what the laser delivered, the lasers consumed a LOT more before to charge. The experiment released 2.5 megajoules vs 2.1 MJ of laser energy. But due to inefficiencies, the lasers consume ~330 MJ to charge, with the energy stored in 3,840 high-voltage capacitors for 60 seconds before being released in a 400-microsecond burst. See “Energizing the Lazers“.

Even by those caveats, the experiment is a massive scientific breakthrough — but don’t think you are about to enjoy free and clean energy tomorrow. Or next year. Or in 20 years or, perhaps, even 50 years. Commerciality is far, far away. If ever. 

Many obstacles remain. One example, the current lasers used in the experiment can fire, at best, only **once a day**. For commerciality, they will need to fire several times **per second**.

So the good news for countries with thermal coal reserves is they still have a few decades to dig it all up and burn it while it’s worth something.

As commenter RickWill says: They spent $3.5 billion to produce the heating power of 10 grams of coal

(Again, last weeks numbers)

They have spent USD3.5bn on the reactor to get a gain of 0.4MJ. Enough to vaporise 100 grams of water. Or equivalent to 10 grams of coal. Baby steps comes to mind. Power was impressive though. It appears the laser is rated at 1PW. Civilisation’s entire electrical generation averages 0.003PW. So the laser would not need to fire often to get a decent power output. But then it only produced a gain [of] 20%. So it would need 5 times the internal generation to that sent out.

I guess they say that these reactions can make big gains once the conditions are right but USD3.5bn to produce what you get out of half a cents worth of coal suggests it is still a big mountain to climb. Maybe within 30 years. Just as the last of the die-hard CO2 demonisers shuffle off.

h/t to John Connor II,  DD and Bill in AZ, and RickWill.

Photo: Eruption of a solar flare by NASA’s Solar Dynamics Observatory (SDO). Enhanced by rawpixel.

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