At least ITER has a plausible, in a sci-fi story sense, way of creating a sustainable fusion reaction to which more fuel could be given. The fact the neutrons produced, if it did reach the high Q ratios, would irradiate and break down everything involved, is probably 2070's scientists and engineers problems to solve.

> is probably 2070's scientists and engineers problems to solve.

With some clever choices in building materials, we may be able to dismantle ITER and its successors to use them as fission fuels.

In that paradise of abundant cheap solar and wind power, only weapons people will be interested in fusion.

They will probably be trying to come up with zero-fallout things they can use tactically.

I do software for a living so that gives you my level of ignorance of the real world.

I do have two question about solar

- is it “drivable” / “pilotable” ?

meaning reacting to surge in the grid? My understanding is that this feature is highly desirable for a grid.

- can we actually build enough solar panel, physically ?

Don’t we need some rare earth thingy that is not in sufficient quantity on our planet as far as we know ? ( follow up : if there is enough, will there be enough in 200 years ? )

The "rare-earths thingy" is a common, transparent lie told frequently about both solar and wind. No rare-earths are used in any solar panel. Some wind turbine generators have used them, but not the big ones. And, "rare-earths" are not in fact rare. So, a double lie.

Solar panels provide cheap power generation on a schedule. For dispatchability, you rely on storage. There are many different kinds of practical, efficient storage; which are used where will depend on local conditions. Which will be cheapest isn't clear, but probably not batteries. Batteries used won't need lithium, or rare-earths, either

The lie most frequently repeated is that storage needs some sort of "breakthrough". Second is that the small amount built out means more than that there is not enough renewable power yet to charge it from; when there is will be time to build it. In the meantime, we fill in with NG burning. The third is that "pumped hydro", the most common used just now, needs "special geography". Hills are very common.

The lie most frequently repeated about solar is that there is any shortage of places to put it. It is most efficiently floated on water reservoirs, where it cuts evaporation and biofouling, although efficiency is only one consideration. It shares nicely with pasture and even crop land, cutting water demand and heat stress without reducing yield.

There will never be any shortage of wind or solar: need more, build more; materials needed are all abundant. Likewise storage. Costs are still falling as fast as ever, but are already lowest of any energy source ever known.

> And, "rare-earths" are not in fact rare.

It's not a lie but is an unfortunate synonym. They are rare in the sense that they are rarified, spread thin everywhere not concentrated in ores.

They are in ores, but are mixed with other lanthanides that they are expensive to separate from. Two of them, yttrium and scandium, are not lanthanides and are relatively easy to separate out.

A new powerfully magnetic iron-nickel allotrope may eliminate much of the market for several of them.

In regards to your first question, the word you're looking for in google-able energy industry jargon is "dispatchable". And yes, dispatchability of intermittent generation is achieved in a couple of ways in contemporary electricity networks:

  1. Deliberately backing off wind or solar generation from full capacity to provide reserves for demand spikes, transmission/generator outages, etc.  This means other generation that may otherwise not have generated at all over that period, is brought online to cover the shortfall.

  2. Co-locating grid-scale batteries at intermittent generation sites ("hybrid generation facilities" in energy industry jargon) to cover short-term contingency events.

Thank you, not my industry and not my language so “dispatchable” is a valuable keyword for me. ( it would be “pilotable” in French; if you ever have to discuss that abroad with my snotty kind )

Anyway. What I read is : having something else on the side can make solar dispatchable. Realistically, what would be that other things ?

Nuclear don’t like to be turned on/off. Wind has the same issue… are we saying the good ol’ coal burning kettle ?

Solar and wind power are not sufficient for spacecraft, and many other applications. Fusion power still has very interesting applications.

Most likely, spacecraft will rely on power delivered via laser.

If anybody succeeds in working out D-3He fusion, that could work in a spacecraft. (D-T, no.) We could probably scare up enough 3He to use for that, if there weren't too many.

If anybody in the universe is doing interstellar travel I think they would have developed D-D fusion which is somewhat more difficult than D-³He or D-T fusion but probably possible with the a scaled up version of the same machine.

Outside the frost line there is a lot of water and a higher percentage of D relative to H so it seems possible to "live off the land" between the stars without being dependent on starshine. A D-D reactor would produce ³He and T, a lot of those products would burn up in the reactor because the reaction rates are high but it would probably be possible to separate some of those out and use it as a breeder reactor that makes fuel for D-³He and D-T reactors elsewhere. I could picture the big D-D reactor running on a large comet or dwarf planet like Pluto producing D-³He for smaller reactors on spacecraft. (D-T not only produces a lot of neutrons but the T has a half life of 12 or so years and won't last for long journies.)

My guess is that interstellar travelers would develop a lifestyle that works around the frost line, where generic bodies above a certain size have liquid water inside. If they were grabby they might consume Ceres or Pluto but might not really care about dry, idiosyncratic worlds like the Earth and Mars.

Anybody doing interstellar travel should hang their collective head-analog in shame if they haven't mastered aneutronic p-11B fusion yet. (They will need to have figured out how to reflect xrays.)

Having got used to spending interminable ages out in the infinite chill void, they probably have come to prefer being there, so have no desire to roast deep in a stellar gravity well. Their equipment might not even work if warmed too much.

Solar is completely sufficient for 99% of applications.

Honest question, because I want that to be true at scale.

Do we know how to store it properly yet? How does solar pan out in case of surge ( eg : very cold winter night )

I think parent was talking about space applications.

Anyway unlike fusion, seasonal thermal storage is viable and available now, and will be scaled up in immediate future. Also, with electrical vehicles inducing massive investment into the grid, there will be both pressure and resources to solve the rest.

How do you power a moon base with solar? 14 days of battery?

Fine. How do you power a Europa base with Solar? A Neptune probe?

>How do you power a moon base

For those interested in near term answer:

https://www.nasa.gov/mission_pages/tdm/fission-surface-power...

Since we're talking in present tense that's the remaining 1%.

Moon base can be fine with power beamed from a satellite or plain mirrors in orbit, no atmosphere in the way. Might end up being still cheaper than hauling nuclear reactor there plus all the infra to reliably dump waste heat from it.

"Solar and wind power are not sufficient for spacecraft"

I guess you're right that solar is useful for 99% of spacecraft -- in that they use it currently. Not a very useful observation

"and many other applications"

Power in polar regions. How well does Solar work in Antarctica? Or Alaska for that matter?

It works super-great, collected in the tropics and shipped in chemical form. Before you object to depending on imported liquid fuel, consider that most of the world does already.

The main difference is that literally anybody can make it, not just "oil exporting countries" and "fuel refiners". And, will. And export excess production when local tankage is full.

Last I looked, round-tripping solar via liquid fuel and back to electricity was under 2% before transport costs

Maybe look again without assuming hydrocarbon. Ammonia is a good transport medium, liquid at room temperature under low compression.

> How do you power a moon base with solar? 14 days of battery?

Either that or a place near one of the poles where you get water and lots of sunshine. A small fission reactor is a handy thing to have, however.

> Fine. How do you power a Europa base with Solar?

A lot more solar panels, or wire loops harnessing Jupiter's magnetic field and Europa's momentum, etc. Fission is still cool for that.

> A Neptune probe?

Now we enter the nuclear fission territory. Maybe fusion, some day.

Laser beams from solar concentrators are likely until aneutronic fusion pans out, if ever. Maybe after that, too.

Why won't fusion still be a worthwhile goal even if we do have abundant solar/wind?

Abundant and cheap are relative terms. Solar and wind could be abundant in a "powers everything we have now and for the foreseeable future of population growth" sense, but maybe not in a "gigantic power-hungry megaprojects which aren't remotely possible today" sense?

Also, is solar truly renewable ? Don’t we need some rare earth component to manufacture them.

What happen when we run out of that ?

Solar needs nothing that can be run out of. Likewise, storage. There are plenty of lies repeated, about that and about missing "breakthroughs".

Never heard about space and that sound outright silly. We do parking and we have space for that crap.

The other was deeply ingrained in my understanding. That’s good news. I need to do my own research, like the crackpots are saying.

> The fusion startups are spending down investors' money with zero possibility of payback (Helion conceivably excepted), because if they did get Q>1, they have no workable way to harness it. ITER will not even try to produce one watt-second of electricity. Its follow-on demo reactor won't start building until 2050, if not further delayed.

You seem to be awfully certain of that. I'm not an expert in this area, but my understanding is that the MIT Arc reactor is planned to use FLiBe as a liquid coolant that absorbs heat/neutrons/etc from the fusion reaction and is pumped into heat exchangers to boil water to run turbines. I mean, maybe there's some details not worked out and maybe I'm misunderstanding how it works, but it seems like a plan to generate electricity to me.

There's no plan to hook ITER up to a thermal plant because it's a research reactor not a power plant, but there's no conceptual reason they couldn't do it. (Not that ITER is a great example; the design is already antiquated before it's even finished.)

"Some details"... Have you ever built anything?

Driving steam turbines, even with other costs at zero, leaves you uncompetitive with renewables. But other costs would be very, very far from zero. Extracting the grams of tritium at PPB concentration dissolved in 1000 tons of FLiBe every day so you have fuel for tomorrow is an expensive job all by itself.

Making a whole new reactor every year or two because it destroyed itself with neutron bombardment is another.

> Driving steam turbines, even with other costs at zero, leaves you uncompetitive with renewables.

Everything gets beaten by renewables when they're at high output.

But renewables plus reliable storage costs a lot more, and there's no way it's cheaper than steam turbines attached to a bottomless source.

You seem to forget that storage also has no operating expense.

The cost of operating a steam turbine far exceeds the cost of the coal or uranium driving it. But the steam turbine would not be the only operating expense for fusion. We don't know exactly what it would cost to sieve a thousand tons of molten FLiBe every day to get out the tritium produced that day, because no one even knows any way to achieve it at all. But it would certainly be a huge daily expense, if achieved.

> You seem to forget that storage also has no operating expense.

Who said operating expense only? I was definitely considering capital costs too, amortized over a few decades.

Steam turbines are fine for backing up unreliable renewables.

> But the steam turbine would not be the only operating expense for fusion. [...]

Okay, but I was only addressing the idea of steam turbine costs by themselves.

Combined-cycle gas turbines are fine for backing up renewables and storage. They are used for that today. As the amount of renewables and then storage built out increases, the amount of time the gas turbines must run, and thus total operating expense, declines.

It should be clear that to build out storage when there is not surplus renewable generating capacity to "charge" it from would be foolish. The immediate exception is to time-shift renewable energy generated at midday peak for evening delivery, as is being done successfully today.

Steam turbines, by contrast, are expensive to operate, and slow to start up and shut down.

Capital expense of renewables is very low already, and still falling. Even substantial overbuild to charge storage from does not change this. Cost of various forms of storage is falling even faster. By the time much storage is needed, it will be very cheap.

> Combined-cycle gas turbines are fine for backing up renewables and storage.

So are plain steam turbines, if you have cheap steam.

> Steam turbines, by contrast, are expensive to operate, and slow to start up and shut down.

Huh? Combined cycle setups use steam turbines as part of the system. Steam turbines can ramp up and down plenty fast. It's traditional heat sources that don't ramp well.

> By the time much storage is needed, it will be very cheap.

That would be nice but I'm not depending on it, and I'm definitely not going to assume that long term storage will ever be cheaper than steam turbines.

> There's no plan to hook ITER up to a thermal plant because it's a research reactor not a power plant

Interestingly, that's not really true: IIRC the japanese team working on the WCCB breeder module (that uses supercritical water as coolant) plans on connecting the water loop to a small turbine. If they succeed it would be the first ever electrical power produced from fusion.

Ability of steam to drive a turbine doesn't seem to be in dispute.

Making tea would be better theater, if they need that, and cheaper: "the first tea ever brewed by over-unity fusing neutrons".

If they can get a continuous fusion reaction going converting the heat energy from that to electricity won't be a problem. Getting a contained fusion reaction that gives out more energy than input is the problem how to convert that into electricity is not going to be a problem.

> If they can get a continuous fusion reaction going converting the heat energy from that to electricity won't be a problem.

Even accepting the qualification that's not just a mere matter of engineering, capturing that heat from a source that hot is not without trouble. A bit like how there is plenty of energy in a single lightning strike and yet we can't easily catch it even though in principle 'just build a large enough capacitor and connect it to a lightning rod' is a workable recipe.

> Getting a contained fusion reaction that gives out more energy than input is the problem

Not in the least because the container itself is a very hard problem to solve.

> how to convert that into electricity is not going to be a problem.

It is also a problem, albeit a lesser one.

The better way to look at all of these fusion projects is a way to do an end run around arms control limitations with as a very unlikely by-product the possible future generation of energy. But I would not hold my breath for that. Meanwhile, I'm all for capturing more of the energy output by that other fusion reactor that we all have access to, and learning how to store it over longer periods. Preferably to start with a couple of days with something that doesn't degrade (think very high density super capacitor rather than a battery), but I'll take advanced battery technology if it can be done cheap enough per storage cycle. We're getting there.

There’s not plenty of energy in a lightning strike.

https://engineering.mit.edu/engage/ask-an-engineer/is-there-...

Funnily enough it's about the same order of magnitude as the fusion event discussed in this TFA: about 1 MJ.

Energy from one hohlraum ≈ energy from two lightning strikes

It doesn't make heat. It makes fast neutrons. Turning them into usable heat is a project of its own.

Turning dumb heat into electric power is expensive. Nothing that depends on doing that can ever compete with wind and solar, anymore.

Tritium doesn't grow on trees. Making it by blasting those hot neutrons into a thousand tons of FLiBe is easy enough. Getting your few grams a day, at PPB concentration, out of that thousand tons of stuff is... nobody has any idea how. But you need to, to have fuel for tomorrow.

No, there won't be any of that. It would be fantastically more expensive than fission. Fission is not competitive, and gets less so by the day. Fusion is nothing but a money pit (with the just barely-possible exception of D-3He).

You've been all over this thread with some aggressive takes that are pretty seriously not supported.

> Turning dumb heat into electric power is expensive. Nothing that depends on doing that can ever compete with wind and solar, anymore.

This isn't even strictly true today when focusing on current "dumb heat sources":

https://en.wikipedia.org/wiki/Cost_of_electricity_by_source#...

"cost of extension of operations of existing nuclear power plants (LTO, long-term operations) has the lowest LCOE of low-carbon energy sources; "

I'm going to go with the OECD and NEA on this one.

> Tritium doesn't grow on trees.

https://en.wikipedia.org/wiki/Breeding_blanket

Saying that there are unknown engineering challenges is kind of a "duh", otherwise we wouldn't be researching we would be implementing. As you also mentioned there are other alternatives which we could consider than tritium.

> Fission is not competitive, and gets less so by the day.

https://www.sciencedirect.com/science/article/abs/pii/S03062... yeah that's not true

> Fusion is nothing but a money pit (with the just barely-possible exception of D-3He).

We genuinely don't know if fusion is a money pit or not, because we don't have any idea how much a successful form will cost. Tritium blankets may be easy or not. Maybe helion's D-3HE will have a breakthrough. Maybe it's ICF.

I've not seen suggestions by anyone that wind and solar build-outs stop, or get diminished. Indeed at this point because the cost are low, industry will continue to invest in them regardless.

However, we will need a lot more energy production than folks think. We need to decarbonize the atmosphere. And that's going to require a lot of power.

All that aside, solar and wind are not getting you to mars in a timely fashion. We have reasons to research fusion that escape large commercial power generation.

Cost of solar and wind are still plummeting. Anything that can match them today won't tomorrow. OECD and NEA agree.

Not going to Mars sounds like a great plan. Sign me up!

We certainly need a lot more energy production but to decarbonize the atmosphere there has be a target level with an evidential basis on which to proceed. If it's considered (as by many) that we have a climate emergency (though this is not reported at all in the IPCC report) then any decarbonization at all will obviously serve for starters. If this is not the case then there are other considerations such as the fact that as CO2 levels have risen so has global food production - about 30% over the last 30 years.

Simulations with multiple global ecosystem models suggest that CO2 fertilization effects explain 70% of the observed greening trend, followed by nitrogen deposition (9%), climate change (8%) and land cover change (LCC) (4%). CO2 fertilization effects explain most of the greening trends in the tropics, whereas climate change resulted in greening of the high latitudes and the Tibetan Plateau.. https://sites.bu.edu/cliveg/files/2016/04/zhu-greening-earth...

This is not a surprise given that carbon is needed for plant growth, a fact well understood by commercial growers who pipe CO2 into their greenhouses. So one issue might be, if decarbonization is successful then what might be the acceptable level of reduction in global food supply?

Another issue relates to temperature. From an analysis of 974 million deaths in 384 locations across 13 countries it’s been concluded that twenty times more people die from the cold as from the heat.https://composite-indicators.jrc.ec.europa.eu/sites/default/... A recent paper (Dec 12 2022) regarding heart attacks states “extreme temperatures accounted for 2.2 additional deaths per 1,000 on hot days and 9.1 additional deaths per 1,000 on cold days.” Circulation. doi.org/10.1161/CIRCULATIONAHA.122.061832.

Do any of the reports present an ethical problem? No, they do not given an extreme interpretation of climate models.

Climate catastrophe denialism is a strange hill to choose to die on.

Direct influence on economic variables and individuals are the smallest of its effects.