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Comment by moloch-hai | Hacker News Reader

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.

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.

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?

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.

>How do you power a moon base

For those interested in near term answer:

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

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

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 ?

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