How "efficient" is electron transport as an energy medium?

[SunnyD]

Originally posted by: So

Originally posted by: SunnyD

Originally posted by: So
...Snip...

I'll cut to the chase in the hopes that you do as well oh resident expert.

Answer the original question then. HOW efficient is... say... the energy output of a nuclear reactor from the raw form(s) that it produces and the form(s) which are directly utilized in powering the turbine which produces said electricity?

How much potential energy is lost from the core material that is never recovered in terms of ALL possible forms of energy output, particularly the forms which we don't/can't utilize with current technology?

Finally, I'd be interested in finding out exactly how much of the electrical output from the turbine actually is utilized in terms of efficiency across the grid that it serves.

I know there's several questions there, so go ahead and do your best, and feel free to be technical - no need to dumb it down unless you really want to.

Please, please read the article on carnot efficiency I linked. A nuclear fuel bundle produces heat. That heat has to be converted to work (power) by some process. With nuclear reactors, the only known process that can produce significant amounts of power is a steam turbine, driven by the rankine cycle. The efficiency of that process is limited by the carnot efficiency. This all depends on the design of the turbine, and if it's a pressurized water reactor, the heat exchanger. I'm an electrical engineer, so my thermo days are long past me, but no matter how many efficiency improvements you do, ANY process that converts heat into energy is limited by the carnot efficiency. I really don't feel like doing the calcs to get you concrete numbers, and I'm betting that PWR / BWR reactor heat rates are at least corporate secrets. Basically, we're already doing well for generators (see http://en.wikipedia.org/wiki/Combined_cycle) -- this article says as much as 85% efficient, which given that this: (http://en.wikipedia.org/wiki/C...versible_heat_engines) gives us an ideal equation, which will yield an ideal efficiency of 85.3%, (with a Tc of 852.15k and a Th of 1172.15k) so we're pretty darn close to the best possible.

And this is (partly) what I'm talking about. We're limited to utilizing nuclear "fuel" to generate heat, even though it gives off another fairly potent type of energy (radiation). This is all part of my (abstract) line of thinking here... wouldn't it be nice if we could utilize both the heat energy as well as the energy from the free radiation that isn't converted into heat? How much potential energy of that nuclear "fuel" itself that decay is converting into liberated energy is being utilized by our current processes? I'm guessing here, but I'd venture that it's not close to the realm of 85%. It may be we're utilizing the heat energy to that point, but not the entire sum energy types that are being produced by said fuel.

 

[So]

Originally posted by: SunnyD

Originally posted by: So

Originally posted by: SunnyD

Originally posted by: So
...Snip...

I'll cut to the chase in the hopes that you do as well oh resident expert.

Answer the original question then. HOW efficient is... say... the energy output of a nuclear reactor from the raw form(s) that it produces and the form(s) which are directly utilized in powering the turbine which produces said electricity?

How much potential energy is lost from the core material that is never recovered in terms of ALL possible forms of energy output, particularly the forms which we don't/can't utilize with current technology?

Finally, I'd be interested in finding out exactly how much of the electrical output from the turbine actually is utilized in terms of efficiency across the grid that it serves.

I know there's several questions there, so go ahead and do your best, and feel free to be technical - no need to dumb it down unless you really want to.

Please, please read the article on carnot efficiency I linked. A nuclear fuel bundle produces heat. That heat has to be converted to work (power) by some process. With nuclear reactors, the only known process that can produce significant amounts of power is a steam turbine, driven by the rankine cycle. The efficiency of that process is limited by the carnot efficiency. This all depends on the design of the turbine, and if it's a pressurized water reactor, the heat exchanger. I'm an electrical engineer, so my thermo days are long past me, but no matter how many efficiency improvements you do, ANY process that converts heat into energy is limited by the carnot efficiency. I really don't feel like doing the calcs to get you concrete numbers, and I'm betting that PWR / BWR reactor heat rates are at least corporate secrets. Basically, we're already doing well for generators (see http://en.wikipedia.org/wiki/Combined_cycle) -- this article says as much as 85% efficient, which given that this: (http://en.wikipedia.org/wiki/C...versible_heat_engines) gives us an ideal equation, which will yield an ideal efficiency of 85.3%, (with a Tc of 852.15k and a Th of 1172.15k) so we're pretty darn close to the best possible.

And this is (partly) what I'm talking about. We're limited to utilizing nuclear "fuel" to generate heat, even though it gives off another fairly potent type of energy (radiation). This is all part of my (abstract) line of thinking here... wouldn't it be nice if we could utilize both the heat energy as well as the energy from the free radiation that isn't converted into heat? How much potential energy of that nuclear "fuel" itself that decay is converting into liberated energy is being utilized by our current processes? I'm guessing here, but I'd venture that it's not close to the realm of 85%. It may be we're utilizing the heat energy to that point, but not the entire sum energy types that are being produced by said fuel.

Radiation from the nuclear fuel is going to heat up the water and / or the containment vessel, providing useful energy, any energy that escapes is a microscopic fraction, otherwise we'd have anyone who walked near the containment vessel dying in minutes.

 

[SunnyD]

Originally posted by: So
Radiation from the nuclear fuel is going to heat up the water and / or the containment vessel, providing useful energy, any energy that escapes is a microscopic fraction, otherwise we'd have anyone who walked near the containment vessel dying in minutes.

Um, isn't that the point of the "containment vessel"?

The radiation is indeed doing some work, but I'm certain a good bit of the energy is ultimately lost in the end, not just a tiny fraction.

Again though - this is my conjecture and slightly beside the point. I ask the questions for a reason (cause I'm curious!). I hope it's at least somewhat interesting, otherwise I'm not using my energy efficiently!

 

[Jeff7]

Originally posted by: So
Okay, you desperately need a physics class before you think any more about this. Your working definition of energy seems to have more to do with a new-agey touchy-feely concept of energy rather than the real world physical concept of energy -- the ability to do work.

Yeah....raw energy?

Electricity is a very good way of transporting energy from one place to another, and if we ever figure out room-temperature superconductors, we'll be able to transmit it with almost no loss.

SunnyD, you also mention the "raw energy" of nuclear reactors - that'd be thermal energy, quite chaotic in nature. It just makes a bunch of particles vibrate like crazy.
That's where the loss occurs - trying to use that chaos to convince electrons to move in an orderly fashion.

Originally posted by: AyashiKaibutsu

Originally posted by: artikk
I wish we could use fusion already.

What do you think we'd do with Fusion besides boil water with it to turn turbines? This threads all about how energy is moved so changing how it's generated won't change that.

Well sure, but the allure of fusion reactors comes from the plentiful fuel supply, minimal generation of low-level radioactive waste, and no risk of a runaway meltdown-style reaction.

Originally posted by: So
Losses due to "converting" energy from electrical to mechanical and vice versa are *very* low and efficiencies have quietly been improving and approaching the ideal since the beginning of the twentieth century. There are losses, but those losses are dictated by the laws of thermodynamics.

I was told during one course that there is research being done into creating ceramic-based engines, not only for cars, but for any sort of combustion engine. Ceramics can endure incredible temperatures before experiencing undesirable changes in their physical properties. This would allow for much higher burn temperatures, thus improving the thermodynamic efficiency.

Originally posted by: PlasmaBomb
WTH is raw energy?

It's like, whoa man.

Originally posted by: SunnyD

Originally posted by: So
Radiation from the nuclear fuel is going to heat up the water and / or the containment vessel, providing useful energy, any energy that escapes is a microscopic fraction, otherwise we'd have anyone who walked near the containment vessel dying in minutes.

Um, isn't that the point of the "containment vessel"?

The radiation is indeed doing some work, but I'm certain a good bit of the energy is ultimately lost in the end, not just a tiny fraction.

Again though - this is my conjecture and slightly beside the point. I ask the questions for a reason (cause I'm curious!). I hope it's at least somewhat interesting, otherwise I'm not using my energy efficiently!

The containment vessel is meant to contain radioactive materials in the event of a catastrophic failure of any sort.
And I don't think the radioactivity of the reaction mass has much of any impact on the net energy production. The heat produced is a result of atomic fission, not the radiation. The total energy contained within the radioactive particle or photon emissions is fairly low; we just regard it as "potent" because we're so fragile against it. Kind of like venom from an inland taipan - it's not an inherently "bad" or "powerful" substance, but a very tiny amount of can kill a person.

The only place you'll find radioactive decay doing any active power generation is in RTEGs in spacecraft, and their output is quite low.

Originally posted by: SunnyD

Originally posted by: PlasmaBomb
WTH is raw energy?

The actual carrier of the potential energy (eg: photon, radiation, heat, etc).

Radiation can be either particles or photons.
Alpha: helium nucleus, 2 protons, 2 neutrons.
Beta: Don't remember, either a single neutron, or a single electron?
Gamma: Photons. Light. Very high frequency, lots of energy per wave/photon/particle/whatever light wants to be.

Heat: It's just atoms bouncing around like crazy - kinetic energy.

 

[So]

Originally posted by: SunnyD

Originally posted by: So
Radiation from the nuclear fuel is going to heat up the water and / or the containment vessel, providing useful energy, any energy that escapes is a microscopic fraction, otherwise we'd have anyone who walked near the containment vessel dying in minutes.

Um, isn't that the point of the "containment vessel"?

The radiation is indeed doing some work, but I'm certain a good bit of the energy is ultimately lost in the end, not just a tiny fraction.

Again though - this is my conjecture and slightly beside the point. I ask the questions for a reason (cause I'm curious!). I hope it's at least somewhat interesting, otherwise I'm not using my energy efficiently!

I think you're incorrect. I'm fairly sure (not a NukeE) that little energy is lost like that. But realistically, no there is going to be no quick breakthrough that turns a hot pile of metal into electricity at 100% efficiency.

There is one big improvement to be made: if someone could come up with a ductile (not brittle) superconductor that is superconductive up to, oh, say 150 deg F and cheap, we could save the small resistive losses all over the power grid. They *would* add up. You can significantly reduce losses by going to higher voltages and to DC, but superconductors would be even better.

 

[Jeff7]

Originally posted by: So
I think you're incorrect. I'm fairly sure (not a NukeE) that little energy is lost like that. But realistically, no there is going to be no quick breakthrough that turns a hot pile of metal into electricity at 100% efficiency.

There is one big improvement to be made: if someone could come up with a ductile (not brittle) superconductor that is superconductive up to, oh, say 150 deg F and cheap, we could save the small resistive losses all over the power grid. They *would* add up. You can significantly reduce losses by going to higher voltages and to DC, but superconductors would be even better.

And there would surely be other advances to be made. Conductors could be made much smaller, which would lead to smaller package sizes of various electronic and electromechanical things. Or think of computers - there are surely resistive losses in small circuit traces, as well as problems within the nanoscopic wiring on a CPU die.

Then there's the diamagnetism of superconductors. You could make maglev trains rather easily.
I'd imagine that you could also put a few ball bearing manufacturers out of business.

 

[So]

Originally posted by: Jeff7

Originally posted by: So
I think you're incorrect. I'm fairly sure (not a NukeE) that little energy is lost like that. But realistically, no there is going to be no quick breakthrough that turns a hot pile of metal into electricity at 100% efficiency.

There is one big improvement to be made: if someone could come up with a ductile (not brittle) superconductor that is superconductive up to, oh, say 150 deg F and cheap, we could save the small resistive losses all over the power grid. They *would* add up. You can significantly reduce losses by going to higher voltages and to DC, but superconductors would be even better.

And there would surely be other advances to be made. Conductors could be made much smaller, which would lead to smaller package sizes of various electronic and electromechanical things. Or think of computers - there are surely resistive losses in small circuit traces, as well as problems within the nanoscopic wiring on a CPU die.

Then there's the diamagnetism of superconductors. You could make maglev trains rather easily.
I'd imagine that you could also put a few ball bearing manufacturers out of business.

True. The social and economic impacts of the first company to commercialize such a superconductor would be almost unimaginably huge. Bigger than fusion, realistically, hell, bigger than warp drive.

 

[Jeff7]

Originally posted by: So
True. The social and economic impacts of the first company to commercialize such a superconductor would be almost unimaginably huge. Bigger than fusion, realistically, hell, bigger than warp drive.

And just plain fun stuff, too. You know, power your house with a wire the size of a hair.

 

[badkarma1399]

Originally posted by: So

snip

True. The social and economic impacts of the first company to commercialize such a superconductor would be almost unimaginably huge. Bigger than fusion, realistically, hell, bigger than warp drive.

Whoa...whoa whoa... Bigger than the warp drive?? On behalf of star wars, star trek and sci-fi fans everywhere, explain yourself!

*furiously googles diamagnetism of superconductors*

 

[sao123]

Originally posted by: Jeff7

Originally posted by: So
Okay, you desperately need a physics class before you think any more about this. Your working definition of energy seems to have more to do with a new-agey touchy-feely concept of energy rather than the real world physical concept of energy -- the ability to do work.

Yeah....raw energy?

Electricity is a very good way of transporting energy from one place to another, and if we ever figure out room-temperature superconductors, we'll be able to transmit it with almost no loss.

SunnyD, you also mention the "raw energy" of nuclear reactors - that'd be thermal energy, quite chaotic in nature. It just makes a bunch of particles vibrate like crazy.
That's where the loss occurs - trying to use that chaos to convince electrons to move in an orderly fashion.

Originally posted by: AyashiKaibutsu

Originally posted by: artikk
I wish we could use fusion already.

What do you think we'd do with Fusion besides boil water with it to turn turbines? This threads all about how energy is moved so changing how it's generated won't change that.

Well sure, but the allure of fusion reactors comes from the plentiful fuel supply, minimal generation of low-level radioactive waste, and no risk of a runaway meltdown-style reaction.

Originally posted by: So
Losses due to "converting" energy from electrical to mechanical and vice versa are *very* low and efficiencies have quietly been improving and approaching the ideal since the beginning of the twentieth century. There are losses, but those losses are dictated by the laws of thermodynamics.

I was told during one course that there is research being done into creating ceramic-based engines, not only for cars, but for any sort of combustion engine. Ceramics can endure incredible temperatures before experiencing undesirable changes in their physical properties. This would allow for much higher burn temperatures, thus improving the thermodynamic efficiency.

Originally posted by: PlasmaBomb
WTH is raw energy?

It's like, whoa man.

Originally posted by: SunnyD

Originally posted by: So
Radiation from the nuclear fuel is going to heat up the water and / or the containment vessel, providing useful energy, any energy that escapes is a microscopic fraction, otherwise we'd have anyone who walked near the containment vessel dying in minutes.

Um, isn't that the point of the "containment vessel"?

The radiation is indeed doing some work, but I'm certain a good bit of the energy is ultimately lost in the end, not just a tiny fraction.

Again though - this is my conjecture and slightly beside the point. I ask the questions for a reason (cause I'm curious!). I hope it's at least somewhat interesting, otherwise I'm not using my energy efficiently!

The containment vessel is meant to contain radioactive materials in the event of a catastrophic failure of any sort.
And I don't think the radioactivity of the reaction mass has much of any impact on the net energy production. The heat produced is a result of atomic fission, not the radiation. The total energy contained within the radioactive particle or photon emissions is fairly low; we just regard it as "potent" because we're so fragile against it. Kind of like venom from an inland taipan - it's not an inherently "bad" or "powerful" substance, but a very tiny amount of can kill a person.

The only place you'll find radioactive decay doing any active power generation is in RTEGs in spacecraft, and their output is quite low.

Originally posted by: SunnyD

Originally posted by: PlasmaBomb
WTH is raw energy?

The actual carrier of the potential energy (eg: photon, radiation, heat, etc).

Radiation can be either particles or photons.
Alpha: helium nucleus, 2 protons, 2 neutrons.
Beta: Don't remember, either a single neutron, or a single electron?
Gamma: Photons. Light. Very high frequency, lots of energy per wave/photon/particle/whatever light wants to be.

Heat: It's just atoms bouncing around like crazy - kinetic energy.

I think his point was why arent we collecting these high energy photons and convert them to a useable form, thus being slightly more efficient. After all, its only the infrared radiation being used to express heat. We should be able to collect the full spectrum of radiation inside a reactor as such and use it.

 

[StageLeft]

It's pretty good. AFAIK a good battery can be charged and then release the vast majority of watts they took in without loss (heat).

 

[Jeff7]

Originally posted by: sao123
I think his point was why arent we collecting these high energy photons and convert them to a useable form, thus being slightly more efficient. After all, its only the infrared radiation being used to express heat. We should be able to collect the full spectrum of radiation inside a reactor as such and use it.

Yes, I understand that, but I'd venture a guess that the energy coming out of it as gamma radiation, or whatever other forms are being generated, is very minimal compared to what's generated by the fission reaction.


Consulting Google in the meantime.....

 

[So]

Originally posted by: sao123
I think his point was why arent we collecting these high energy photons and convert them to a useable form, thus being slightly more efficient. After all, its only the infrared radiation being used to express heat. We should be able to collect the full spectrum of radiation inside a reactor as such and use it.

We *are* collecting these photons! They collide with the moderator and the vessel and heat it up!

<bangs head on desk>

 

[Jeff7]

Originally posted by: So

Originally posted by: sao123
I think his point was why arent we collecting these high energy photons and convert them to a useable form, thus being slightly more efficient. After all, its only the infrared radiation being used to express heat. We should be able to collect the full spectrum of radiation inside a reactor as such and use it.

We *are* collecting these photons! They collide with the moderator and the vessel and heat it up!

<bangs head on desk>

Google was not fruitful; I'm likely not searching for the right terms.

About how much energy is released by uranium that's just undergoing radioactive decay? The closest I could find was info on plutonium decay in RTEGs, but the power figures given were of the electrical output, after the thermal energy worked its way through the thermopiles.


I'd still guess that it's almost nothing when compared to what you get from the fission reaction.

 

[BrownTown]

There is some serious science fail all over the place here...

First off, concerning some numbers, power plants are 30%-50% efficient, the "grid" is 93% efficient. In all honesty these are pretty damn good numbers compared to most other energy transportation/conversion mechanisms (like say your cars engine). As for where the energy comes from in nuclear reactions, the radiation DOES carry the energy, it very rapidly collides with other molecules heating them up. And yes if you stood next to the pressure vessel during operation of a nuclear reactor you WOULD die of radiation poisoning after some amount of time).

I did find some info on exactly where the energy goes, the majority seems to be maintains in the fission fragments while the rest is in the released ratiation. But its important to note, in all cases this energy can be transported to the water because these high energy particles will impact other molecules. Remember that "heat" is a measrue of the average kinetic energy of the particles in an object. Those initial fission fragments with 80MeV of finetic energy correspond to 8 MILLION degrees. These 8 million degree particles quickly average out to instead having 8000 particles at 1000 degrees for example. This 1000 degree water (steam) is what powers the turbines.

 

[So]

Originally posted by: Jeff7

Originally posted by: So

Originally posted by: sao123
I think his point was why arent we collecting these high energy photons and convert them to a useable form, thus being slightly more efficient. After all, its only the infrared radiation being used to express heat. We should be able to collect the full spectrum of radiation inside a reactor as such and use it.

We *are* collecting these photons! They collide with the moderator and the vessel and heat it up!

<bangs head on desk>

Google was not fruitful; I'm likely not searching for the right terms.

About how much energy is released by uranium that's just undergoing radioactive decay? The closest I could find was info on plutonium decay in RTEGs, but the power figures given were of the electrical output, after the thermal energy worked its way through the thermopiles.


I'd still guess that it's almost nothing when compared to what you get from the fission reaction.

Uh, it *is* a fission reaction.

 

[BrownTown]

Originally posted by: So

Originally posted by: Jeff7

Originally posted by: So

Originally posted by: sao123
I think his point was why arent we collecting these high energy photons and convert them to a useable form, thus being slightly more efficient. After all, its only the infrared radiation being used to express heat. We should be able to collect the full spectrum of radiation inside a reactor as such and use it.

We *are* collecting these photons! They collide with the moderator and the vessel and heat it up!

<bangs head on desk>

Google was not fruitful; I'm likely not searching for the right terms.

About how much energy is released by uranium that's just undergoing radioactive decay? The closest I could find was info on plutonium decay in RTEGs, but the power figures given were of the electrical output, after the thermal energy worked its way through the thermopiles.


I'd still guess that it's almost nothing when compared to what you get from the fission reaction.

Uh, it *is* a fission reaction.

hes talking about decay (as in releasing an alpha particle), not fission (breaking in half).

 

[Jeff7]

Originally posted by: So
Uh, it *is* a fission reaction.

Hm, maybe we're thinking of different things or something. I interpreted the question by SunnyD to refer to the "idle" radiation put out by the uranium itself - just plain radioactive decay. Which....yeah, I guess that is sort of fission occurring, slowly, sort of.

That then was what I was thinking of in comparison to a full-out nuclear reaction that's done with the explicit purpose of generating loads of heat in a hurry in order to generate power.

If that makes any sense.

 

[sao123]

Originally posted by: So

Originally posted by: sao123
I think his point was why arent we collecting these high energy photons and convert them to a useable form, thus being slightly more efficient. After all, its only the infrared radiation being used to express heat. We should be able to collect the full spectrum of radiation inside a reactor as such and use it.

We *are* collecting these photons! They collide with the moderator and the vessel and heat it up!

<bangs head on desk>

something doenst make sense...

fission releases a wide spectrum of energy wavelengths... microwaves, visible light, infrared, ultraviolets, xrays, gamma rays, and high energy gamma rays.

So... infrared is the only rediation responsible for heating:
there is still a large percentage of this going to waste... like the microwaves, xrays, gammas, ultraviolets, and visible light. --Everything that is not infrared is being wasted.

we need to capture all these photons which are NOT being used to heat the water for steam, and charge some photocells or something.

 

[Born2bwire]

Originally posted by: SunnyD

Electricity is *not* "electron transport", which is a biological term, nor is it the movement of electrons, it is the propogation of an electric (and associated magnetic) field in a conductive medium.

Alright, I'll give you the confusing terminology - but electrical current is essentially the transport of electrons across a medium (in most cases - though it can potentially be any charged particle, but most often electrons).

The transport of electricity (above DC) is the same as the transport of light. There isn't any other real way to transport appreciable amounts of usable energy.

 

[edro]

Maybe there is "electricity" on the quark or even string level. Just throwin' the idea out there...

You can send my royalty checks via PM.

 

[Sea Moose]

Apparently a guy called Nikola Tesla came up with a method to provide free electricity to everyone using a Tesla Coil. I believe that the concept was similar to your radio. Electricity travels through air waves similar to radio waves.

Unfortunately, Tesla lost his mind.

http://en.wikipedia.org/wiki/Nikola_Tesla

 

[Casawi]

Here is my 2 cents.
One method that is currently used at a smaller scale is RF energy harvesting, currently used on some passive RFIDs and such. So this method could be use for low power devices. So my thinking is always something like we need to be able to more work using less energy. In other words, if we can make our machine/devices/ whatever else that uses energy use less and less of it, alternative energy resources would make more sense.
I don't know what you are trying to get at by saying raw energy, whatever the case might energy will always need to be converted to the most efficient for of use. Again using less and less energy to convert our energy to a usable form would be the goal.

 

[Analog]

Utilities lose about 40% of all generated electricity from the powerplant to the user. So its not really that good. However, if you use superconductors, the losses would be theoretically zero. That doesn't include transformers, interconnects and the like.

Also, solar cells are only ~20% efficient. Think of the improvements there too.

 

[PlasmaBomb]

Originally posted by: SunnyD

Originally posted by: So
Radiation from the nuclear fuel is going to heat up the water and / or the containment vessel, providing useful energy, any energy that escapes is a microscopic fraction, otherwise we'd have anyone who walked near the containment vessel dying in minutes.

Um, isn't that the point of the "containment vessel"?

The radiation is indeed doing some work, but I'm certain a good bit of the energy is ultimately lost in the end, not just a tiny fraction.

Again though - this is my conjecture and slightly beside the point. I ask the questions for a reason (cause I'm curious!). I hope it's at least somewhat interesting, otherwise I'm not using my energy efficiently!

People need to do basic research...
wiki

Instantaneously released energy...............MeV
Kinetic energy of fission fragments...............169.1
Kinetic energy of prompt neutrons...................4.8
Energy carried by prompt ?-rays.....................7.0

Energy from decaying fission products
Energy of ß--particles....................................6.5
Energy of anti-neutrinos..................................8.8
Energy of delayed ?-rays................................6.3
Sum.........................................................202.5




Energy converted into heat in an operating thermal nuclear reactor 202.5 MeV

Efficiency at producing heat in an operating nuclear reactor = (Used energy/Released energy)*100

(202.5/202.5)*100 = 100% at generating heat.

Gee how can we get more than 100% efficiency :roll:

The losses occur elsewhere, where efficiency is limited by Carnot's Rule, which has been linked before.