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Comment by nordsieck | Hacker News Reader

> Given climate change, if Helion works then it would be in the interest of the US for it to spread worldwide as quickly as possible. Especially since it uses a mostly-aneutronic reaction.

The US may want cheap energy to spread world wide. That doesn't necessarily mean the US wants fusion tech to spread world wide.

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There's nothing scary about this. If it works it'll be very cheap, dispatchable power with no need for storage, curtailment, long-distance transmission, or demand management. It works just as well in any location, is massively scalable, and isn't really helpful for making bombs.

What makes you think this is going to be cheap? There is a lot of high tech going into this, costs for a fusion device would likely eclipse that of an EUV stepper (if we are talking small scale devices), for plants the size of ITER that's a whole nother level.

Fission was supposed to be super cheap too, but construction costs rendered that a fantasy.

Construction costs for fission are largely bloated due to safety, activist and political concerns that span the realm of pragmatic and necessary to pure fantasy as well.

Aneutronic fusion would (hopefully) bypass a lot of that.

* The safety is massively different than fission because there is no 'run away' reaction. If you turn off the power, fusion will stop. Fission will keep going once started, and can be very dangerous if the cooling system fails.

* I do believe the fusion paths Helios is using emit neutrons, which is a big safety concern. Not only is neutron radiation directly deadly to humans, it's also a challenge to maintain containment. Neutrons are not magnetic, so matter must be used as a shield. Most materials that absorb a neutron will itself become radioactive. I'm unsure about the number of neutrons Helios is emitting, or will emit as they scale up.

Their combined D-D/D-He3 reaction will emit 6% of its energy as neutron radiation, compared to 80% for D-T. Mostly they'll be lower-energy neutrons, and it's only a 50MW reactor. They don't plan to make it bigger, just to make lots of them.

They're considering doing the D-D reaction in a separate reactor to produce the He3. The D-He3 reaction is purely aneutronic, and while some D-D will still happen, they can tune it so it doesn't happen much. That would mean very little neutron radiation at the power plants.

> The D-He3 reaction is purely aneutronic, and while some D-D will still happen, they can tune it so it doesn't happen much. That would mean very little neutron radiation at the power plants.

Yea. I'm just very curious as to what these numbers look like in practice. Neutrons are essentially waste emissions with their plan, but physics and engineering constrains will determine how much they can tune out D-D reactions.

> very curious as to what these numbers look like in practice

At their stated "optimum" temperature of 200 million kelvin[0] or ~17 keV, the selectivity of the two cross-sections (D-H3/D-D) is about 0.7[1].

Let x = the fraction of D (we'll generously assume no T contamination, so the remainder 1-x is He3), plug in the reaction energies[2], and rearrange.

Graph is here: https://www.wolframalpha.com/input?i=plot+y+%3D+1.225+x%5E2%...

The top line is total non-neutron power, and the bottom line is neutron power. The horizontal axis is the fraction of D in the mix, and the vertical axis is proportional to power.

It might help compare the relative tradeoffs if you zoom in on the rising slope of the power curve, and normalize both curves to 1: https://www.wolframalpha.com/input?i=plot%3A+y%3D1%2F3.9503+...

[0] https://www.reuters.com/technology/microsoft-buy-power-nucle...

[1] https://commons.wikimedia.org/wiki/File:RxDT-DD-DHe3.jpg

[2] https://en.wikipedia.org/wiki/Nuclear_fusion#Criteria_and_ca...

In fact, even for D-T fusion the NRC recently decided to regulate reactors like accelerators instead of like fission reactors.

Also, we never mass-produced fission reactors. Helion wants to build a factory making twenty 50MW reactors per day, shippable by rail.

When it becomes clear that fusion can displace coal those safety, activist and political concerns will immediately pop up again

And any country that chooses to keep using a dirty, unhealthy, more expensive, 250-year-old energy supply over helium-3 fusion will rapidly fall behind.

Ok but that's a different story.

Just look at what's going on with solar https://twitter.com/ArmandDoma/status/1656323112349179907

Yes in theory it should be easy to shut these people up with fusion but historically it hasn't been.

You are describing a scenario that's very scary for any economy that depends on fossil energy sources to some extent.

Do you really not see the geostrategic advantage in being able to control who gets "free" energy and who doesn't?

Sure but I think climate change trumps that by a wide margin. Plus, our most acute geopolitical foe gets most of its revenue by selling fossil fuels, so it'd work out nicely to steal all their customers.

And it's not like the US controls who gets energy right now, or would be able to for more than a short time. China is already attempting to copy the Helion reactor; if it works then efforts like that will ramp up worldwide.

I wonder if there's already a paper, or a fictional book, about what happens if someone invents something that makes fossil fuels obsolete within, say, a year. The OPEC countries would suddenly be faced with losing one of their biggest income streams. It would be interesting to speculate...

Of course there are different levels of obsolence, all the petrol cars won't disappear, unless someone invents a magic liquid to replace petrol/diesel with something that works identically but without the pollution.

You still need fossil fuels for the chemical industry, transportation, etc.

Even if electricity becomes cheap (we can already do that with wind and solar) changing everything else is a huge task.

Well you need hydrocarbons, but cheap scalable fusion would make it a lot easier to source the hydrogen from water, the carbon from ambient CO2, and mush them together.

Transportation is already in the process of shifting. EV cars and trains, obviously, are the present. EV cargo vans are "days away" from the present (especially looking at things like Walmart's massive uptake in EV logistics, but also Amazon and UPS and FedEx's various deals). EV semitrucks are "months away" from the present. Air and sea have the longest lead times and are indeed the furthest behind, but are seeing a lot of pressure to explore cheaper alternatives (and are talking about very interesting electrification ideas and are seeing prototypes and early adopters).

I heard a rumor once, and it may be more fictional speculation than reality, that OPEC shows most of the signs of a "going out of business" sale. That they know the market window is shrinking and are doing their best to make the most of it in an "everything must go" fashion.

(The rumor suggested that's why there was a weird sudden drop in oil and gas prices several years back and then prices nearly "flatlined" for a few years there rather than sticking to a slow inflation-locked climb as it had been. The rumor was that OPEC had started to liquidate its reserves as fast as possible without crashing the market.)

If that was the case, one would hope that OPEC members were also smart enough to plan for after the "going out of business sale" and smartly socking away the money into long term investments. (Further speculation: given the real estate booms in UAE and Qatar, especially, and attempts to spin some of those cities as world tourism destinations there may even be evidence that that is what they have been trying to do.)

> Of course there are different levels of obsolence, all the petrol cars won't disappear, unless someone invents a magic liquid to replace petrol/diesel with something that works identically but without the pollution.

I don't think it will need "magic", I think the feedback loops between supply-side and demand-side economics can handle it all on their own, and possibly (probably, IMO) surprisingly quickly once things start to snowball: gas pumps are already low margin "loss leaders" for convenience stores and supermarkets. As prices get higher the usefulness as "loss leaders" shrinks. As EVs spread, demand drops which could drop prices (temporarily) but that also lowers the usefulness as a "loss leader". Any such price drops are almost guaranteed to be temporary because as demand drops, production should drop. Production is capital heavy and much of production once it shuts down, in theory shuts down for good (especially if demand isn't expected to go back up) because the costs for restarts become increasingly too expensive. As the usefulness for gas as a "loss leader" drops below certain thresholds, consumer gas pumps start to disappear. As gas pumps start to disappear, demand for EVs increases, furthering the drop in demand for gas, exacerbating the disappearance of gas pumps. Eventually, as that cycle snowballs, ICE range anxiety returns with a vengeance and petrol cars become museum pieces too expensive to drive.

Because it is a feedback snowball, it could happen seemingly abruptly, almost like magic.

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