Author Topic: Diamonds Powered Nuclear Batteries  (Read 9902 times)

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Offline EEVblog

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Diamonds Powered Nuclear Batteries
« on: December 01, 2016, 03:45:02 am »
http://www.bristol.ac.uk/news/2016/november/diamond-power.html



Quote
Despite their low-power, relative to current battery technologies, the life-time of these diamond batteries could revolutionise the powering of devices over long timescales. The actual amount of carbon-14 in each battery has yet to be decided but one battery, containing 1g of carbon-14, would deliver 15 Joules per day.  This is less than an AA battery.  Standard alkaline AA batteries are designed for short timeframe discharge: one battery weighing about 20g has an energy storage rating of 700J/g. If operated continuously, this would run out in 24 hours. Using carbon-14 the battery would take 5,730 years to reach 50 per cent power, which is about as long as human civilization has existed.

That's 4.13mWh/day, or 172uW continuous power output per 1g. That's pretty useful.
« Last Edit: December 01, 2016, 03:49:54 am by EEVblog »
 
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Offline janekm

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Re: Diamonds Powered Nuclear Batteries
« Reply #1 on: December 01, 2016, 04:00:00 am »
And here I thought it was hard to get LiPo batteries shipped...  :-DD
 

Offline Falcon69

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Re: Diamonds Powered Nuclear Batteries
« Reply #2 on: December 01, 2016, 04:05:59 am »
Don't let Samsung get these batteries!  Whole cities will be lost!

Seriously though.  I might just see the free energy revolution happen in my time (well, as close to 'free energy' as one can get I guess). This is a great start, And I hate bananas, but I'll hold a diamond.  ;)
 

Offline EEVblog

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Re: Diamonds Powered Nuclear Batteries
« Reply #3 on: December 01, 2016, 04:48:46 am »
De Beers are going to be pissed!
 

Offline BravoV

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Re: Diamonds Powered Nuclear Batteries
« Reply #4 on: December 01, 2016, 04:54:42 am »
Voltnuts will be hysterical aren't they ? As their vref will be powered for eternity.  >:D

Offline nanofrog

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Re: Diamonds Powered Nuclear Batteries
« Reply #5 on: December 01, 2016, 03:25:17 pm »
De Beers are going to be pissed!
FWIW, they have an industrial diamond division.
« Last Edit: December 01, 2016, 03:26:53 pm by nanofrog »
 

Offline alanb

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Re: Diamonds Powered Nuclear Batteries
« Reply #6 on: December 01, 2016, 03:27:32 pm »
So we won't need the Batterisers after all!
 

Offline SeanB

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Re: Diamonds Powered Nuclear Batteries
« Reply #7 on: December 01, 2016, 04:06:26 pm »
De Beers are going to be pissed!
FWIW, they have an industrial diamond division.

Yes, and most of the natural diamond lands up there as well, only a tiny part is gem quality.

Big industrial business as well in diamond coating things, and with making large industrial stones.

However this battery will have a lousy energy to mass ratio, plus a really high internal impedance, limited by the rate of decay and the consequent electron emission.
 

Online DenzilPenberthy

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Re: Diamonds Powered Nuclear Batteries
« Reply #8 on: December 05, 2016, 01:49:27 pm »
It's great to see this project getting such good exposure. These guys are colleagues of mine. Let me know if you have any technical questions...

I wonder if a radioactive diamond will be allowed through customs in a mailbag :)
 

Offline AndyC_772

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Re: Diamonds Powered Nuclear Batteries
« Reply #9 on: December 05, 2016, 02:15:46 pm »
Imagine the conversation with an environmentalist...

"We've invented a battery that lasts for millennia, contains no toxic chemicals, and is nearly 100% efficient in turning stored energy into clean electricity."

"Wow, great, fantastic. What's it made of?"

"Nuclear waste"

" :scared: "

" :palm: "

Offline helius

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Re: Diamonds Powered Nuclear Batteries
« Reply #10 on: December 05, 2016, 02:30:49 pm »
The novel "Infinite Jest" is set in a world where most energy needs are generated with nuclear waste.
 

Offline FrankBuss

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Re: Diamonds Powered Nuclear Batteries
« Reply #11 on: December 05, 2016, 02:40:31 pm »
Why are the reactors and waste on boats in the video and the stupid happy music? And the meter at 1:50 and 3:50 is a bit misleading, because it shows 0% at one end and 100% at the other end, and the needle in the video falls linear to 50%, suggesting that it is 0% in 10k years, but in fact it would be at 25%. But the speaker says it right.

But is it only an idea or do they have a prototype? Why does it generate a current without any moving parts? And they are right, diamonds are very hard, so what could possibly go wrong?

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Offline helius

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Re: Diamonds Powered Nuclear Batteries
« Reply #12 on: December 05, 2016, 03:42:12 pm »
C-14 decays into N-14 through beta decay (one of the neutrons decays into a proton, an electron, and an antineutrino). The beta electron can be captured by some materials and converted directly to an electric current: these materials are said to be betavoltaic.
 

Offline tszaboo

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Re: Diamonds Powered Nuclear Batteries
« Reply #13 on: December 05, 2016, 04:55:39 pm »
But why diamond. What is wrong with graphite? It is conducting, but as far as I understand, its just another type of nuclear battery. Also, What happens with the diamond, when some atms decay into Nitrogen? Falls apart, or what?
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Online edavid

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Re: Diamonds Powered Nuclear Batteries
« Reply #14 on: December 05, 2016, 05:26:42 pm »
But why diamond. What is wrong with graphite? It is conducting, but as far as I understand, its just another type of nuclear battery. Also, What happens with the diamond, when some atms decay into Nitrogen? Falls apart, or what?

It appears that they are using diamond semiconductor diodes as the generator:

Quote
... the man-made diamond is able to produce a charge simply by being placed in close proximity to a radioactive source ...

This seems like a questionable decision, considering the poor performance of current diamond semiconductors.  Maybe the idea is that it would be less vulnerable to degradation from radiation damage than other materials.  Since they haven't tested it with a Carbon-14 source yet, they probably don't know.


In the prototype, the radiation source is external:

Quote
The team have demonstrated a prototype ‘diamond battery’ using Nickel-63 as the radiation source.

So the next step, if any, would be testing with external Carbon-14, which might well be in the form of graphite, and it would be a long way down the road before they would actually incorporate the source into the diamond structure.  It might not ever be worth the hassle.
« Last Edit: December 05, 2016, 05:57:09 pm by edavid »
 

Offline AndyC_772

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Re: Diamonds Powered Nuclear Batteries
« Reply #15 on: December 05, 2016, 05:50:57 pm »
What happens with the diamond, when some atms decay into Nitrogen? Falls apart, or what?

I imagine the acceptable answer to that question depends on who is asking. This being the internet, of course, I imagine most people would immediately fall into one of two groups...

One group has probably already decided that the number of atoms will be so trivially small as to be inconsequential, and in any case, they're simply trapped within the diamond lattice. Some slight discolouration after 1000 years or so may be detectable.

For the other group, the pressure of nitrogen gas builds up undetectably over time, before eventually shattering the outer coating, sending razor sharp diamond shards out in all directions, and releasing a pocket of dangerously radioactive gas into the environment. Misery and chaos ensue, especially if the device has been medically implanted.

Hopefully someone who knows the actual science involved will be along soon to provide an objetively correct answer. Until then, any answer is just noise, my suggestions included.

Online DenzilPenberthy

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Re: Diamonds Powered Nuclear Batteries
« Reply #16 on: December 06, 2016, 11:14:29 am »
One of the scientists is in my workshop right now :)  I asked him - basically this decay into nitrogen limits the concentration of C14 you can incorporate into the diamond at the start. If you put too much in then yes it falls apart after a while. If you put less in then it's not such an issue.
 

Offline John Heath

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Re: Diamonds Powered Nuclear Batteries
« Reply #17 on: December 10, 2016, 04:06:54 pm »
I have that as 100 u watt / sec or 100 u amp at 1 volt. I can see how it would be safe as a diamond is the hardest. However a diamond being carbon will burn.  It could double as a highly radioactive and very expensive cigarette lighter. Hmmm.
 

Online DenzilPenberthy

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Re: Diamonds Powered Nuclear Batteries
« Reply #18 on: December 16, 2016, 02:41:06 pm »
They are doing an 'Ask me anything' on Reddit right now if you want to ask questions... ...

https://www.reddit.com/r/IAmA/comments/5io9na/we_are_physicists_from_the_university_of_bristol/
 

Offline Codebird

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Re: Diamonds Powered Nuclear Batteries
« Reply #19 on: December 19, 2016, 08:25:17 am »
Pitiful power output, expensive raw materials... it's the successor to the tritium battery. Just enough power to run a clock.

The security required to handle anything nuclear plus the cost of extracting just C14 from graphite is going to make sure this remains a niche thing.
 

Offline LukeW

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Re: Diamonds Powered Nuclear Batteries
« Reply #20 on: January 19, 2017, 12:31:37 am »
It's basically a betavoltaic battery, with a beta-active radionuclide and a semiconductor junction which captures the charge carrier injection and generates electricity. Betavoltaics are an established, existing thing - not snake oil. Good for specialized applications where a tiny amount of power is needed for a very long time with no external energy supply or maintenance, but not something that is ever going to run a light bulb.

http://www.bristol.ac.uk/cabot/research/casestudies/2016/diamond-battery.html

http://www.bristol.ac.uk/media-library/sites/cabot/documents/Diamond_battery_FAQs_Nov_2016.pdf

Carbon-14 is a low-energy beta emitter, like tritium, but it has a far longer half-life. The low-energy beta particles won't escape the betavoltaic structure, so it's safe. They won't penetrate very far, and if the beta particles did get out without being captured, this would be an undesirable waste of energy. Neither the radiation nor the radioactivity is ever going to escape outside the device. The radiation is internally captured and turned into electricity.

Diamond is a hard material, it can be fabricated by established techniques like chemical-vapor deposition, and it keeps the radioactivity tightly bound within the diamond matrix. It sounds like they are talking about fabricating a single structure which contains both the radioactive source and the betavoltaic diode as a single piece, all fabricated together, potentially meaning that fabrication is cheaper, easier and more scalable. They're talking about CVD from methane, and combining layers of 12C diamond and 14C diamond. The scalability seems limited by the feedstock of enriched 14C methane.

They're talking about 1 gram (170 GBq, 4.6 Ci) of 14C (for comparison, there's 74 GBq of tritium in the NanoTritium batteries.) If the average beta energy is 49 keV you get about 115 joules per day, so you need about 13% overall capture efficiency in the betavoltaic to get 15 joules per day, which seems plausible.

15 joules per day at 2 volts is about 87 microamps. A tiny amount of power, but maybe useful for tiny systems, MEMS devices, microscopic low-power sensors, nanotechnology etc.

Just like a photovoltaic cell which is essentially the same thing, for a betavoltaic there is a voltage-current curve with a maximum power point somewhere in the middle, and the quoted voltage is only the open-circuit voltage with no current draw.

The City Labs NanoTritium batteries are a commercial product now, and they claim 50-350 nanoamps maximum current (at zero volts) and an open-circuit voltage of 2.4 volts, for a device with 74 GBq of tritium in it.

http://www.citylabs.net/index.php?option=com_wrapper&view=wrapper&Itemid=25

That's an existing, manufacturable, packaged, licensed commercial product. That's what I think they would have to economically compete with, for the same small niche markets and applications.

It's not clear where they plan on getting the 14C from. They're talking about recycling graphite moderator waste from nuclear power reactors, but graphite-moderated reactors are relatively rare (UK gas-cooled AGR reactors, RBMKs, and the prismatic/HTGR or pebble-bed type systems.) I'm sure one AGR moderator contains lots of carbon, but is it really practical to separate 14C from it?

How much 14C is formed in a graphite moderator? You're talking about two successive thermal neutron captures on 12C (or one neutron capture on relatively rare natural 13C), and the overall cross section therefore doesn't seem like it's going to be that impressive. The 14C is dispersed in a matrix of mostly 12C, it's dilute, so you can't get it with any significant specific activity and you can't chemically separate it. Unless you're talking about isotope separation which is intrinsically expensive and energy intensive.

Carbon is pretty light, so enrichment is somewhat possible by distillation or chemical exchange. For example turning all the carbon into a chemical form such as cold liquid carbon monoxide, followed by repeated distillation. This is easier than something like gas centrifugation for uranium where the mass difference is far smaller, and cheaper, but I don't think it's a practical or economical way of recycling reactor graphite by the ton.
 

Offline Lord of nothing

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Re: Diamonds Powered Nuclear Batteries
« Reply #21 on: February 07, 2017, 01:29:11 am »
Its possible to separate the radio active particles by smash the graphite blocks and flush everything truth some centrifuge?
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Offline Codebird

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Re: Diamonds Powered Nuclear Batteries
« Reply #22 on: February 07, 2017, 07:04:29 am »
Quote
Its possible to separate the radio active particles by smash the graphite blocks and flush everything truth some centrifuge?

Yes. Possible, but not efficient - the process needs to be repeated many, many, many times. That's why it's so expensive.
 

Offline richard.cs

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Re: Diamonds Powered Nuclear Batteries
« Reply #23 on: February 08, 2017, 12:03:58 pm »
There are 28 Magnox reactors in various stages of decommissioning, each with over 1100 tonnes of graphite, the prototype AGR has also been decommissioned, and there are 14 AGRs currently operating with around 1300 tonnes of graphite in each, all expected to cease operation by 2030. There are 11 currently operating RMBKs with 5 decomissioned, each with about 2000 tonnes. That is a sizeable supply of irradiated graphite. Irradiated CO2 is also produced by the AGRs, but is (or at least was in the 1990s) vented into the atmosphere after filtering to remove particulates.

This document: http://web.ornl.gov/info/reports/1977/3445605743782.pdf suggests that more 14C is formed from the nitrogen impurities in the graphite than from the 13C in the the graphite, but does not consider the formation of 14C from 12C via 13C at all (possibly the double capture contribution is negligible?). Table 5 gives graphite 14C as 16.27 Curies per Megatherm, so if we take Sizewell A as an example, having operated at 1010 MW thermal for 40 years, we take a stab at it having been online for 80% of that time, then in round numbers that's 160,000 Curies, or about 140 Curies per tonne. I make a kg of pure 14C 4460 Curies so each tonne of graphite must contain about 30 grams of C14.

That's quite a low concentration, but then I don't know what concentration they wanted?

In the reddit ask anything they talk about using laser separation, they're obviously planning on a significant amount of processing. I haven't checked if their numbers and mine match, if they're within a factor of ten I'll be happy.

 

Offline MagicSmoker

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Re: Diamonds Powered Nuclear Batteries
« Reply #24 on: February 11, 2017, 07:24:58 pm »
...
It's not clear where they plan on getting the 14C from. They're talking about recycling graphite moderator waste from nuclear power reactors, but graphite-moderated reactors are relatively rare (UK gas-cooled AGR reactors, RBMKs, and the prismatic/HTGR or pebble-bed type systems.) I'm sure one AGR moderator contains lots of carbon, but is it really practical to separate 14C from it?

Well, the Chernobyl reactors were graphite moderated, IIRC...  :scared:
 


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