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Comment by MrDresden | Hacker News Reader

Effectively unlimited clean energy is the goal.

Let that sink in. Yes, ITER it self isn't ever going to be producing that energy but it is a step in the direction of that end goal.

How can 5 billion dollars extra be considered too much for that end goal? Especially given everything that has happened on the world stage in the last 4 years, and had dramatic effects on the project. Not to mention that the collective yearly budgets of the nations involved is higher than 10 trillion dollars.

Unlimited clean energy.

A personal view on this is also that a rising tide lifts all boats. If the slow moving, very expensive international government project causes more nimble private enterprise to see a way to get there first and get a slice of the budget cake then great!

Unlimited clean energy. It is worth it, IF we can get there.

Multiple sized eggs in different baskets is the best plan.

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That is a worthy goal to be sure but we already know how to do it, in a way that's much cheaper and way less dangerous - synthesizing hydrogen from solar electricity.

Unlimited, clean, predictable energy. If we had spent a few billions on it last year, we'd be using that energy this year already. No breakthroughs needed, everything is already well-known and proven.

My understanding is that current hydrolysis systems are pretty inefficient (single-digits efficiency) and even worse once you factor in the cost of storing and transporting cryogenic hydrogen. That doesn't make green hydrogen a bad idea: it just means the main application for it should be industrial feedstock (for e.g., making steel) and not energy storage.

Single digit would be bad but it's much higher. From wikipedia: "current best processes for water electrolysis have an effective electrical efficiency of 70-80%,[36][37][38] so that producing 1 kg of hydrogen (which has a specific energy of 143 MJ/kg or about 40 kWh/kg) requires 50–55 kWh of electricity."

Granted, converting hydrogen back to electricity has another loss of about 60% IIRC but still, you get to keep almost half of your electricity when storing it via hydrogen. So as long as solar is at most half as expensive as the second best stable energy source it's a win.

0.7×0.6 is not half

It's not viable.

The goal of producing fuel is for explosive, quick release energy. Things like cars, tractors, heavy machinery need fuel. Lighting your home and things like that work fine with predictable trickles of energy that can be produced easily with solar.

The energy density of a fuel like hydrogen means that you need significant surface area to produce usable quantities at scale, quantities that then are burnt quickly. You have to make it at the rate that you use it, which means it's just added complexity in the stack of getting solar energy to where it will be used. It's just solar power with extra steps.

Add to that, solar power isn't this unproblematic perfect solution. It has a whole host of problems. First and most obvious is the mineral requirements to produce it, and extracting those minerals is incredibly destructive. Disposal of waste is also destructive. But another problem nobody talks about that is dismissed because it is seen as a small problem, is the problem of surface area. A limited amount of energy hits the surface of the earth, and life uses every drop of it that it can. Energy production with solar scales two dimensionally. You can't scale this up without significantly damaging ecosystems.

A little box you pump very little resources into that produces absolutely massive amounts of energy, something with a very small footprint that scales extremely well, that's what you want. Solar isn't it. Solar is great, but it's a stopgap for fusion. Everything is a stopgap for fusion.

Nothing at a global scale is without downsides, but solar has fewer problems than any other energy source. It is cheap, easy to deploy anywhere, can reuse existing “ruined” land (buildings, farmland, bodies of water) without needing any new area for the foreseeable future, and is easily dismantled too. Within few years it seems likely it’ll be trivial to recycle it as well.

The only downside is that it’s intermittent, which hydrogen solves. The “extra steps” convert intermittent solar to predictable energy, useable 24/7/365. It’s not a device to transport solar to _where_ it will be used, but _when_ it will be used.

Even if fusion actually worked, it would be inferior in a major way - it concentrates too much energy in a single point. With solar and gas, energy could be distributed and redundant. No sabotage or failure can cut the energy supply to millions of consumers at once, and energy would be created where it’s needed.

Fusion could still be useful for science experiments requiring enormous amounts of energy but IMHO it’s not a good idea as a grid source.

Photovoltaic is only one way sunlight can be made to move electrons.

The concern I have here is that "unlimited free energy" is too good to be true. A bit of healthy skepticism is important in my opinion, and when a promise like that is made based only on theory and a belief that it can be done with enough research it raises alarms for me.

The 10 year, $6bn project is now 14 years old and already spent $20bn. Where did they get so far? Well they not apparently are confident that it was a 29 year, $60bn project all along. They simply can't know that and it seems likely that we would get further down the road with little to show for all the effort and expense.

By all means people should continue to research fusion, but that should be done on a scale more reasonable than asking for a blank check to build a full reactor when we don't even know how it needs to work. In the meantime, we could make real strides in reducing our total energy use if we really did care about that metric.

It’s actually a bit worse - we don’t actually know it’s doable in theory - when you dig into all the steps involved.

We only know it’s doable in the sense that fusion itself has a large net energy release. We don’t know if it’s even theoretically possible (net energy release wise) in the conditions we can potentially create on earth outside of a nuclear explosion.

I heard a podcast with people working at Wendelstein 7-X and they estimated that building a fusion power plant would cost 20 billion €. Far more money is spent on less important things.

I think that 20 billion euros is like the 20 million dollars estimate in the clip below (from the Big Bang Theory)

https://www.youtube.com/watch?v=JLF-8uiiTJ4

When it's overrun to 100 billion € and the project's "about to start showing results", would you feel the same?

> Effectively unlimited clean energy is the goal. > Let that sink in.

No, this was never the goal. At the beginning, ITER was a science project to get the US and the USSR to collaborate on something even if the Cold War was at its height. Similar to the International Space Station. Some project with no real scientific objective, but that could spur the enthusiasm of the masses, so politicians could gain popular support while covertly pursuing a path to rapprochement.

> Unlimited clean energy.

How exactly to you get the tritium? By running some fission reactors, right? Fission reactors are a reality today, and can provide unlimited clean energy already. Why don't they? Because they are expensive? And how do we know fusion reactors, if they ever show up, will be inexpensive?

Ok, here's something else to let sink in. The best fusion reaction out there (deuterium+tritium) yields only about 5 times as much energy per kg of fuel as the fission of uranium or plutonium. Only 5 times, not 50 times or 500 times.

And of course, we don't find tritium in nature, so we need to breed it from lithium using a source of neutrons. You could use a fusion reactor as the source of neutrons (deuterium + tritium = helium + neutron), as you can read on this ITER page [1]. What that page does not tell you is that you would need 100% efficiency to be able to breed your own tritium. Good luck with that. Any deficit will need to come from fission reactors.

Somehow the dream that is sold to people is that once we get fusion reactors, we can stop using the "dirty" fission reactors. It is just a lie.

[1] https://www.iter.org/mach/TritiumBreeding

> you would need 100% efficiency to be able to breed your own tritium

How so? As I understand it, the breeding reaction is exothermic (Li-6 + n -> He-4 + T) so all you need are neutrons, for which (as someone pointed out to me two years ago[1]) neutron multipliers would be used.

[1] https://news.ycombinator.com/item?id=32224650

I was talking about the neutron efficiency, not the thermodynamic efficiency.

As for neutron multipliers, they are currently so far from being realistic that they are essentially science-fiction.

I'm not sure I understand what's 'science-fiction' about lead or beryllium?

Here's some articles about the neutron multipliers. You can go through them and see that they are all talking about feasibility and theoretical considerations. It's not just as simple as shooting some neutrons at a block of lead of beryllium on one side and more neutrons come on the other side.

[1] https://www.sciencedirect.com/science/article/abs/pii/S00223...

[2] https://scipub.euro-fusion.org/wp-content/uploads/eurofusion...

[3] https://publikationen.bibliothek.kit.edu/1000160103

No, I agree, but you specifically mentioned "science-fiction" in the second post, and implicitly denied even their existence in the first post. I think there's a reasonable distance between that, and economic considerations / the fact that test hardware has yet to exist that's presented in those papers.

So best case scenario we have expensive fission nuclear reactors with marginally more output per plant. Why not just spend that money on fission plants.

Also if all reactors are essentially based on boiling water. Why don't we just dig to depths were water is already boiling? I'm sure there are plenty of those areas on the globe.

We are too busy driving rovers on Mars to explore our own planets inner structures.

Many of the deepest shafts are commercial diamond mines. Not science.

Imagine a Liquid Nitrogen cooled probe through the earths volcanic layers. There are probably organisms living there that we have no idea about.

Not right? Breeder reactors are not some sort of perpetual-motion device. They create energy, which can be used for lots of things including more reactions creating tritium by a 'cheaper' route from lithium. Like we use petroleum to power drilling equipment to get more petroleum. The energy released is the part that makes it 'free'.

And isn't that 'four or five times' number, per reaction? Because deuterium and tritium are so much lighter than fissionable materials (by 10X) the energy per kg is truly 50X not 5X. Right?

No, the five times number is per weight, not per reaction. Per reaction, the fusion one Deuterium and one Tritium yields 17.6 MeV [1]. The atomic mass of the components is 5, so you get 3.5 MeV per one unit of atomic mass (also called a Dalton).

Per reaction, fission produces between 190 and 200 MeV. Since the input is one nucleus of U-235 or Pu-239 and one neutron, the mass is either 236 or 240, so the yield is 0.8 MeV per Dalton. So the deuterium-tritium reaction is only 4.4 times more energetic than fission, per unit of mass.

As for your first part, I didn't get what you were trying to say.

> Breeder reactors are not some sort of perpetual-motion device.

I don't think I implied they are, and I don't think anyone believes in perpetual-motion devices in 2024.

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

> Effectively unlimited clean energy is the goal.

Reality check: We currently have no clean source for abundant tritium.

What if it turns out to practically generate energy from fusion you literally need a star out in space?

Beryllium Copper lining baffled me.

Way softer metal than Tungsten.

I guess its about the density?

Beryllium Copper is one of the highest temp coppers but that ain't saying much for something that generates millions of degrees of plasma....

Beryllium Copper is tough and used for non-sparking tools. I don't see it handling millions of degrees.

Tungsten seems like a good switch... Imagine machining it though...

They are supposedly going to guide this plasma beam in a torriod shape.

What if it crashes into side of vessel?

Tungsten might be good liner but they lose the beam and.......

Don’t we already have effectively unlimited clean fusion energy?

No. Pretty sure you mean nuclear fission, not fusion. They’re opposites. Fission splits the atom and fusion fuses them together.

I believe they mean the sun.

Well that's strictly limited by square meter. Especially based on your geographical location, time of day, and time of year. Solar power is basically useless in Finland for example. It makes sense why northern Europe would want to invest into fusion. Solar is a better solution for areas with higher solar incidence.

It’s unfortunate that countries are unable to trade with each other. There is plenty of sun in countries farther south.

I bet they even have lots of wind power they could trade.

Maybe they could make this sunstuff into something they could sell and ship to the poor sunstarved icedwellers, such as liquid carbonated hydrogen fuel.

Carbon neutral green ammonia and|or methanol are serious contenders for both replacing marine fuels and for being transported to places that long extension cords won't reach.

(2021) https://spectrum.ieee.org/why-the-shipping-industry-is-betti...

(2024) https://fortescue.com/news-and-media/news/2024/03/15/world-s...

4,300 km long extension cord: https://www.suncable.energy/

is producing oxides of nitrogen environmentally okay?

That’s exactly what I meant. It’s way cheaper too. Imagine all the batteries you could buy with that money.

Its an easy mistake to make though. In 2022 many news outlets were reporting the minor fission advancement as a breakthrough that amounted to fission reactors having been "solved".

Depends on your coordinates. In regions with less sunny days the requirements for storage are huge and if you don't have some hydro to spare, may as well consider building some nuclear ppts with a closed nuclear fuel cycle

> Unlimited clean energy.

Far from unlimited. Almost all fusion power plant concepts are thermal power plants. These directly contribute to global warming, and you can’t scale up by more than a couple of orders of magnitude without causing significant climate change.

In the end you’d need to use panels to radiate the waste heat directly to space, but then you have similar land use limitations as solar panels.

There’s no reason to think we actually need that energy. Advanced deep geothermal is probably much easier than fusion. With that you’ve got geothermal near the poles, solar everywhere else and wind/hydro/wave/tide to supplement based on needs and availability.

Helion fusion power plant concept is not thermal. So we can probably make a lot more electricity without heating up the planet too much. In the end it too will be limited by the heat added to the planet.

Heat released by global human energy consumption, every source combined, is insignificant compared by heat received from the sun. (quick calculation 17.7TW / 173PW= 0.01026%). Global warming is caused by greenhouse gases trapping radiation, not by direct heat emissions

All energy we use eventually turns into heat so it doesn’t matter that helion skips a step and converts fusion directly into electricity

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