The Fusion Reactor Is (kinda) Born - new baby steps

[Ser Scot A Ellison]

Leap,

I don't "object" to boilers.  They work and that's wonderful.  It just seems odd to me that we can tap nuclear power and we are using it to merely boil water.

[Ded As Ned]

I don't think SaE was saying we should get rid of water-based technology, but rather he's disappointed the technology was largely abandoned.  My skeptical nature makes me want to blame the fossil fuel conglomerates.  

[karaddin]

2 hours ago, polishgenius said:

If it works it works. Who cares how old it is? We use far, far older techniques everywhere in everyday life because, well, they work. I assume you've got no problem with building houses out of bricks for example. Or fertilising crops with shit.

Hell, let's go with something that there is an alternative to and he's dead set against the alternative. Paper books! Those ereaders are an abomination that excludes Scot from novellas he wants to read!

 

[Ser Scot A Ellison]

Karaddin,

I dislike eReaders.  I'm not "dead set against them".  If someone else wants to read with them go for it.    My daughter has a kindel.  I don't care for them but that's my asthetic preference.

My wife thought of an interesting analogy that sums up my point it's as though we have amazing supercomputers but use them to manage "Pony Express" delivers.  One technology seems out if sink with the other.  

[polishgenius]

10 hours ago, Ser Scot A Ellison said:

My wife thought of an interesting analogy that sums up my point it's as though we have amazing supercomputers but use them to manage "Pony Express" delivers. 

Isn't that what email basically is?

[Michael Seswatha Jordan]

14 minutes ago, polishgenius said:

Isn't that what email basically is?

No, its a vastly improved version of the Pony Express. Ser Scott is saying if we used a computer to track the actual Pony Express, its a comparison as to why he is disappointed in why we haven't come up with better tech than steam turbines.

[The Mance]

11 minutes ago, Michael Seswatha Jordan said:

Ser Scott is saying if we used a computer to track the actual Pony Express, its a comparison as to why he is disappointed in why we haven't come up with better tech than steam turbines.

And if a pony express were still the cheapest and most efficient method we had for physically delivering mail then Scot would have a valid analogy.  It's not, so he doesn't.

[Michael Seswatha Jordan]

59 minutes ago, The Mance said:

And if a pony express were still the cheapest and most efficient method we had for physically delivering mail then Scot would have a valid analogy.  It's not, so he doesn't.

Well, yes you're right. I still at least see his point, and others. I have no clue how any of it works, just does seem as if we would have came up with something different.

[OnionAhaiReborn]

A revival of the Pony Express could be the next hipster craze. Send a message using a smartphone app, 3-5 weeks later a rider will arrive at the recipient's doorstep. There will have to be a surcharge if the rider dies of a snakebite or diphtheria along the way and needs to be replaced, of course.

[Liffguard]

 

12 hours ago, Ser Scot A Ellison said:

My wife thought of an interesting analogy that sums up my point it's as though we have amazing supercomputers but use them to manage "Pony Express" delivers.  One technology seems out if sink with the other.  

Keep in mind, we still sit our arses down in chairs, the fundamental design of which hasn't changed in 6,000 years or so. How come we haven't found a better way to cook food than applying heat to a metal container? Maybe boiling water is just the most efficient, most cost-effective way of producing electricity with our current technology base?

[maarsen]

19 hours ago, Ser Scot A Ellison said:

FN,

Photovoltaic is very inefficient.  At a max only 10-20% of the photons are converted into electricity.  The rest is waste heat.  Steam turbines are much more efficient.  That's what bothers me.

It's as though we can do something but don't know enough about what we're doing to do something interesting with what we are doing.

As some one who actually works on and repairs boilers, they are a very efficient way to transmit energy for short distances. Turbines are also very efficient at generating electrical energy which can be transmitted for long distances. The waste hear from both of these is easily saved and reused to preheat the boiler water and for added efficiency. Old tech is sometimes the best tech.

[Corvinus85]

JJ Abrams knew what he was doing when he designed the new Enterprise with a steam power plant in it. When it comes to generating electrical energy, boilers may just well be... the final frontier. 

[Ser Scot A Ellison]

2 hours ago, maarsen said:

As some one who actually works on and repairs boilers, they are a very efficient way to transmit energy for short distances. Turbines are also very efficient at generating electrical energy which can be transmitted for long distances. The waste hear from both of these is easily saved and reused to preheat the boiler water and for added efficiency. Old tech is sometimes the best tech.

Maarsen,

I know.  My point is not that it is bad.  It is that it seems weird, to me, that we can split or fuse the atom and we are using that vast energy to boil water.  It seems, again to me, that there ought to be a more direct way to convert that energy into usable electical energy.

[maarsen]

Water just doesn't store heat really well but it acts as a really good shield for radiation given off by the reactor, especially neutrons, when using heavy water, as is done up here in Canada. Fusion, if and when it comes, generates neutrons and a water shield is cheap and easy to work with. 

[HobbsTuna]

On 2/6/2016 at 5:53 PM, Free Northman Reborn said:

Come on. "Let's not romanticize fusion?"

Really?

It is fully justified to "romanticize" it. If they can make it work, it changes the world completely.

It is ridiculous to try and downplay its benefits. Fusion will solve our energy needs for a million years or more, and any freshwater needs it may have can easily be fulfilled by fusion power itself, via endless energy for ocean desalination plants.

Fusion power will be one of the greatest leaps forward in human history. But first they must make it work.

Only really if we can make it to Deuterium - Deuterium Fusion. As long as we are stuck with Deuterium - Tritium (not that even that works yet), the Tritium has to come from somewhere, which means breeding blankets, which will negate a lot of the advantages the Fusion plants have over Fission plants.

On 2/6/2016 at 9:21 PM, Ser Scot A Ellison said:

Correct me if I'm wrong but wouldn't we be using fusion to boil water to spin steam turbines if it "worked"?  Does it bother anyone else that boilers are still the most efficient way to generate electical power?  We can harness the power of the atom and its subatomic constituant parts... to boil water.

I keep thinking that in more than a century we'd have come up with a better way to power our civilization.

 

On 2/6/2016 at 9:26 PM, Free Northman Reborn said:

Photovoltaic power is probably the only alternative I can think of off the top of my head, which skips the whole need to use a steam turbine to generate electricity. But yeah, this is something that kind of bothers me too.

Split the atom to get some heat to heat up water to turn a steam turbine. Quite sobering.

That makes me wonder, though. When they talk about putting a nuclear reactor on a spaceship to power it in deep space, or to power a base on the Moon, does that concept rely on the same idea of carting along massive quantities of water to power steam turbines, or is there another direct conversion of nuclear generated heat into electricity that I'm just not thinking of right now?

 

Well leaving your strange aversion against perfectly working technology aside, if you guys want to get rid of the steam turbine you best bet are actually advanced fusion plants. If we ever manage to go aneutronic we can just catch the charged particle stream with a magnet field, still very likely would have some kind of heat absorbent coolant to take care of the gamma rays. 

 

[Ser Scot A Ellison]

HobbsTuna,

Have you read my other posts?  I don't "object" to steam turbines it just strikes me as odd that the most efficent use of nuclear fission or fusion for power generation is heating water to power turbines.  It seems so... indirect.  I know it works.  I simply can't help but wonder if there isn't something we are missing that could be more efficient.

[Spring Bass]

Stirling engines are more efficient at turning heat into electricity, but also bulkier and more expensive. They make more sense for stuff like space probes (where you want efficiency and reliability, and the cost isn't as much of an issue) versus power plants. 

Fundamentally, you're just trying to convert heat output into useful electricity, which is going to be indirect no matter what. The only nuclear reactor designs which dodge this are the "aneutronic" fusion reactor proposals, which produce virtually all of their output in charged particle form. 

One thing I'd also add about fusion is that if you want it to be widely adopted, you'll need it to come online sometime in the next 10-20 years in viable commercial design. If it doesn't come online in commercial design until 2100, it will be too late - we'll have restructured the entire energy grid around making effective use and storage of solar, wind, and tidal power. Fusion reactors would be up against some serious path dependency in grid design by then. 

[Sir Thursday]

Scot - I don't think it's so weird if you break it down into what actually needs to be done. There are a few different ways that energy is produced in a fusion reaction, but a lot of it comes out in the form of heat as a result of high energy particles hitting the shielding on the reactor.

To make use of the Heat it first needs to stored somewhere. The best heat sinks have high specific heat capacity (so that a lot of energy can be stored per degree of temperature raised) and use a fluid to store the heat, so that it can easily be transferred away from the heat source once it has been heated up. Here is a list of the specific heat capacities of various liquids. Only ammonia has a higher Specific Heat Capacity than water of the substances on the list. But ammonia is inconvenient to use because it has a very low boiling point - so it either needs to be stored at very high pressure or piped around the system as a gas. The latter is undesirable because it loses the additional heat storage from the latent heat of vaporisation (eg the energy required to turn liquid into a gas), and I suspect the former is not really practical in a fusion reactor environment.

So, of common liquids water is left as the substance with the best properties for being a heat sink. Given its ubiquity and the relative ease of handling it, it is therefore a natural choice for capturing the heat produced by the reaction. And once you have the heat stored in water, you might as well use steam turbines to convert that heat into electricity - any attempt to transfer the heat further is going to be very inefficient, whereas the science governing extracting electricity from steam is very well understood and highly optimised (the Carnot cycle has been around as a concept for some time and many people have worked on minimising the inefficiencies of steam turbines).

Now, as others have mentioned there are other ways of getting energy out of a fusion reaction. If your reaction generates large quantities of charged particles as its primary output, you can control those particles with magnetic fields and generate a current directly. There's a good article here on the basics of this technology - maybe it will be used in future reactor designs. But it's not a trivial process to implement and there are probably still quite a lot of kinks to be worked out before it is usable in a production environment.

ST