‘Diamond-age’ of power generation as nuclear batteries developed New technology has been developed that uses nuclear waste to generate electricity in a nuclear-powered battery. A team of physicists and chemists from the University of Bristol have grown a man-made diamond that, when placed in a radioactive field, is able to generate a small electrical current. The development could solve some of the problems of nuclear waste, clean electricity generation and battery life.
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Diamond battery
is the name of an alleged prototype battery proposed by the University of Bristol Cabot Institute during their annual lecture[1] held on 25 November 2016 at the Wills Memorial Building. The research presented is hypothetical. This battery is proposed to run on the radioactivity of waste graphite blocks (previously used as neutron moderator material in nuclear reactors) and would last for thousands of years, but has not yet been achieved, despite the claim by Prof. Tom Scott at the annual lecture.
Apart from its long life it is also being presented as a means of making the disposal of nuclear waste easier. Some researchers claim that this discovery can lead to “Diamond Age” of battery power.
The underlying concept for the diamond battery is the unusual property of a synthetic diamond (developed by the University of Bristol) which creates a small electrical current when placed in a radioactive field.[2] Thus, enclosing a suitable radioactive source inside such a diamond will provide ionising radiation to the diamond, which in turn will produce a small electrical current.
Contents
Potential prototype characteristics - it is currently unclear where these values come from Edit
In initial prototypes, nickel-63 has been used as the radioactive source for the diamond.[3]
Voltage – 2 V estimated (Ni-63 1.9 V measured)[4]
Energy – 15.8 MJ over first 5,000 years, or total of 4.4 kWh[5]
Prototype size – 10 mm x 10 mm x 0.5 mm (plus electrodes)[6]
Temperature – physically stable at 750 °C[7]
Carbon-14 Edit
Researchers are trying to improve the efficiency and are focusing on use of radioactive C-14, which is a minor contributor to the radioactivity of nuclear waste.[8]
C-14 undergoes beta decay giving non-radioactive nitrogen and high energy beta particles.[9]
614C → 714N + -10β
These beta particles, having an average energy of 50 keV, undergo inelastic collisions with other carbon atoms, thus creating electron-hole pairs which then contribute to an electric current. This can be restated in terms of band theory by saying that due to the high energy of the beta particles, electrons in the carbon valance band jump to its conduction band, leaving behind holes in the valance band where electrons were earlier present.[10] [11]
C-14 has been chosen as the source of radioactivity mainly because its beta particle radiation is easily absorbed by any solid. The use of diamond, one of the hardest solids on earth, will not only increase the quantity of current generated but will also prevent dangerous radiation from leaking out of the battery.[12]
Extracting C-14 from nuclear waste Edit
In graphite-moderated reactors highly radioactive uranium rods are placed inside graphite blocks. These blocks act as neutron moderators and their purpose is to slow down the fast moving neutrons so that nuclear chain reaction can occur properly.[13] During their use, some of the non-radioactive (C-12) in graphite gets converted into radioactive C-14 by capturing neutrons[14] Once the graphite blocks are removed during station decommissioning their induced radioactivity qualifies them as low-level waste, and disposal is a tough job. Researchers at the University of Bristol earlier showed that radioactive C-14 developed in waste blocks is mainly concentrated on the outer parts of the block. Due to this, a lot of it can be effectively removed from the blocks. This removal can be done by heating the blocks which will release C-14 in gaseous form. After removal, blocks will be less radioactive and more easy to dispose of.[15]
Proposed manufacturing Edit
Researchers propose that C-14 gas obtained by heating the radioactive graphite waste will be collected and subjected to low pressure and elevated temperature, to produce a man-made diamond. This particular man-made diamond, being made of radioactive C-14, will also be radioactive. Hence, its radioactivity make allow it generate small currents. For practical and safe use this radioactive diamond would be enclosed inside a non-radioactive man-made diamond (made from C-12). More diamond will make more current, even with the same radioactivity, and the outer diamond will shield the user from the dangerous radioactivity of the inner diamond.[16]
Advantages Edit
It will possess long life because it will run on radioactivity which takes an enormous amount of time to decay. The half life of C-14 is 5,730 years, so it it will take 5,730 years to lose 50% of its power.
It will ease the disposal of waste graphite blocks by extracting a bulk of the block's radioactive portion.
A diamond battery wouldn't require any coils, moving parts, etc, and hence will be more durable than conventional batteries.
Being made of diamond (one of the hardest materials on earth) it will be more rugged than conventional batteries.[17]
Disadvantages Edit
Its power density will be far lower than that of conventional chemical batteries, restricting its use to low-power electrical devices.[18]
Applications Edit
Due to its long life it could be used for applications where charging or replacing conventional batteries is not feasible, such as in satellites, spacecraft, implantable devices, high altitude drones, etc.[19]
